Michigan State University Extension
Ag Experiment Station Special Reports - 03299579
07/28/98
November 1994 Special Report 79
Status and Potentialof MichiganNatural Resources
Michigan Agricultural Experiment Station,Michigan State University
SPECIAL REPORT
Water Resources Lead Author: Frank M. D'Itri, Institute of Water Research and Department of Fisheries and Wildlife Contributors: John M. Besser, Department of Fisheries and Wildlife; Elwin D. Evans, Michigan Department of Natural Resources; Ruth Kline-Robach, Institute of Water Research; Jody A. Kubitz, Institute of Water Research and Department of Fisheries and Wildlife; Lois G. Wolfson, Insitute of Water Research and Department of Fisheries and Wildlife; and Todd E. Zahniser, Institute of Water Research.
In Michigan, many citizens, legislators, and researchers have recognized the overlap among many areas of concern and the need to develop an overall ecosystem management approach to study and plan for water, air, and land quality improvements.
This realization has evolved as various special interest groups have been drawn together to exchange concerns and ideas for change. In this report, the current situation is described with special emphasis on the various aspects of ecosystem management, recognizing that some areas have been more thoroughly studied than others and that all need more interactive planning. Besides indicating some aspects of what has been and needs to be accomplished and coordinated, some suggestions are made as to likely areas of concern and evaluation in the future.
Rather than being prescriptive, this report hopes to motivate future ecosystem management in a spirit that transcends special interests and recognizes the importance of natural resources to all.
Introduction
Water is Michigan's most distinguishing feature. The Great Lakes cover approximately 40 percent of the state's 96,791 square miles of official surface area. Michigan has at least an additional 1,000 square miles of ponds and inland lakes, 36,350 miles of rivers, and more than 150 waterfalls. The state also boasts 3,288 miles of Great Lakes coastline, a length that rivals the entire U.S. Atlantic seaboard.
Water is constantly in motion in the hydrologic cycle-from t When water falls in the form of precipitation, it may be intercepted and taken up by plants, stored in lakes, infiltrate into the soil, or flow over the surface to a stream channel. The energy of the sun may evaporate the water directly back into the atmosphere, or the force of gravity may pull it down through the pores of the soil to be stored for years as slowly moving groundwater. Some groundwater returns to the surface to supply water to springs, lakes, and rivers. Other water completes the hydrologic cycle by evaporation or by transpiration_when water vapor passes through the leaves of plants to reenter the atmosphere.
Surface runoff is the portion of water that does not infiltrate the soil but flows over the ground surface to a stream channel. It always takes the path of least resistance, flowing from higher to lower elevations, eventually reaching a stream. All of the land that drains to a common lake or stream is in the same WATERSHED. Watersheds are further defined as topographic divides that separate surface flow between two water systems.
Where water infiltrates the ground, gravity pulls it down through the pores until it reaches a depth where all of the spaces are filled or become impermeable. At this point, the soil or rock is saturated, and the water level that results is called the WATER TABLE. The depth of the water table rises and falls in response to precipitation, evaporation, and transpiration. GROUNDWATER is the water in the saturated zone below the water table. In the saturated zone, groundwater flows through the pores of soil or rock both laterally and vertically. This movement is influenced by the permeability of the glacial till and bedrock. An AQUIFER is a formation of soil or rock in the saturated zone that can yield usable amounts of groundwater. An aquifer that is bound on the top by an impermeable material, such as clay, is a CONFINED AQUIFER. When the material above the aquifer is permeable, such as sand, the aquifer is UNCONFINED.
While recharge water enters the aquifer, the groundwater discharged from it may enter a stream or lake. In Michigan, groundwater typically replenishes rivers, lakes, or wetlands. An aquifer may receive recharge from an overlying aquifer or, more commonly, from precipitation followed by infiltration. The groundwater RECHARGE ZONE is that area, either at the surface or below the ground, which provides water to an aquifer.
Watersheds are to rivers as recharge zones are to aquifers. Often watersheds and recharge zones are interconnected, just like streams and groundwater. Because of these connections and the continuous movement of water, all withdrawals and discharges in these areas affect the quantity and quality of the water that eventually reaches lakes, streams, and aquifers. Therefore, properly identifying and managing watersheds and recharge zones is important to preventing the degradation of Michigan's water resources.
Water Availability and Distribution
Climate
The Great Lakes that divide Michigan into two peninsulas dramatically affect the state's climate. Though the weather fluctuates daily, summers are cooler and winters warmer than the harsh extremes found in states of equal latitude. The annual precipitation in Michigan ranges between 28 and 38 inches (Figure 1). The state also experiences lake-effect precipitation, which results when moisture is picked up by air masses passing over the lakes and released over land. Precipitation falls nearly one day in every three, with the greatest amount falling in the southwestern part of the state because it receives moist air from the Gulf of Mexico. Less lake-effect precipitation and limited atmospheric moisture in the summer result in lower annual precipitation for the northeastern portion of the Lower Peninsula. In the western Upper Peninsula, moisture from Lake Superior is largely responsible for about 300 inches of snowfall per year. Most areas receive the highest amounts of precipitation in the spring and summer and the least in fall and winter. Because annual precipitation typically exceeds evaporation and transpiration, Michigan is a net exporter of water. The surplus water enters streams that flow into the Great Lakes, which, in turn, flow to the St. Lawrence River and on to the Atlantic Ocean.
Rivers and Streams
Michigan has been divided into fifty major watersheds (WMU, 1981), but the number can vary depending on the detail of the divisions (Figure 2). (Only two small areas of land are outside the Great Lakes watershed_the western upper peninsula and along the Indiana border. Both these areas drain to the Mississippi River.) Michigan's many rivers and streams are each replenished by their own watershed. Most flow short distances and empty into a Great Lake.
Runoff in a stream channel is the amount of water passing a point in the river over a given time, or simply the flow (Figure 1). This is not to be confused with surface runoff or the water that flows over the land surface after rainfall. Runoff includes water reaching the river through groundwater discharge, surface runoff, and precipitation onto the water surface. Runoff ranges from 6 to 22 inches annually, depending not only on precipitation but on geology, topography and development. Monthly average values at representative sites indicate the variations in seasonal precipitation and river flow (USGS, 1985, 1986, 1993; Nurnberger, 1987; Blumer et al., 1993). Streams in the western Lower Peninsula and the northwestern Upper Peninsula have the most runoff. These areas also have higher precipitation and lower temperatures, resulting in less evaporation.
The amount of flow (runoff) in Michigan rivers changes throughout the year (Figure 1). In general, flow is greater in late winter and early spring when snowmelt and rainfall produce more surface runoff. Though summer is a period of high precipitation, much water is lost through evaporation and transpiration; consequently, the flow of Michigan rivers is lowest in late summer.
In areas where a large portion of the runoff is supplied by groundwater, stream flow is more uniform throughout the year. For example, rivers in the northwestern Lower Peninsula flow over thick and very permeable glacial deposits. They tend to have a groundwater supply that sustains the river in summer and reduces variation in flow throughout the year. In contrast, rivers in southeast Michigan flow over less permeable material, which resists both infiltration and groundwater discharge to the river. This results in a greater variation in flow throughout the year and a lower flow in late summer.
Basin yield is the quantity of water that each square mile of watershed contributes through surface runoff and groundwater discharge to sustain river flow during dry periods. This yield is used to characterize drought flow in Michigan rivers. Rivers with a high basin yield in late summer have sufficient groundwater discharge to sustain river flow during dry periods (Figure 3). Among these are western Michigan streams that flow over highly permeable sand and gravel deposits. In contrast, rivers with a low basin yield are more readily influenced by air temperatures because they are warmer in the summer and frozen over much of the winter. Typically, in late summer these rivers have a low groundwater supply and may even go dry. These streams are located in southeastern Michigan, where the glacial deposits have low permeability, and in the northeastern Lower Peninsula, where shallow limestone bedrock allows large quantities of water to bypass rivers and flow underground directly to Lake Huron.
The abundance of water is a benefit to Michigan; but in times of flooding, the excess water can have devastating effects. A stream is contained within its channel during normal flow but, when intense rainfall or snowmelt produces high runoff, the rising stream overflows its banks and covers its floodplain. Though it is impossible to predict with certainty when floods will occur, statistics are useful for describing the chance that another flood will occur in the future and the extent of the flooding. Approximately 6 percent of Michigan's land area is prone to flooding. Though these areas are spread throughout the state, the most frequent flooding occurs in the southern two-thirds of the Lower Peninsula, especially in areas along Lake Erie, Lake St. Clair, and the Saginaw Bay of Lake Huron.
Inland Lakes
Michigan has approximately 35,000 lakes that are greater than one-tenth of an acre in surface area (Figure 4). One-third of these lakes are larger than five acres in surface area. Most of Michigan's lakes were formed when large ice blocks broke off retreating glaciers and subsequently melted to form kettle lakes. Other lakes have been formed by rivers that have changed course, sinkholes, or sand bars that have isolated former bays of the Great Lakes. Humans have also formed lakes by damming rivers; gravel pits have filled with water to form other lakes. The highest concentration of lakes is in the northwest Lower Peninsula, where glaciers left hills and valleys suitable for lake formation. Lakes are sparse in the Saginaw Bay area where glaciers left flat terrain. Antrim, Roscommon, and Cheboygan counties have the highest density of lakes, covering 11 percent of the land surface. Iron County, with about 2,175, has the highest number of lakes, and Cheboygan County, with over 51,000 acres, has the greatest total lake acreage.
Wetlands
In the early 1800s, the first surveyors sent into southern Michigan reported that the whole territory was swampland; later surveys determined that Michigan was one-third wetland. By 1955, wetlands occupied less than one-tenth of the state. Each of Michigan's 83 counties has a drain commissioner responsible for maintaining the system of ditches that drain the state's developed areas. During the past two centuries, many wetlands were lost through the development of land for agricultural production, highways, parking lots, residential and commercial building sites, industrial plants, marinas, and harbors.
Areas with wet and spongy soil are generally considered to be wetlands. They include swamps, marshes, bogs, and hardwood forest bottomlands. Their value and function depend on their type and location. Wetlands can provide fisheries and wildlife habitat, reduce bank and shoreline erosion along rivers and the Great Lakes coast, improve water quality, and store water to reduce flood damage. These functions have received greater attention in recent years as Michigan's wetlands resources have become more scarce and a new era of protection and conflicts over wetland management has arrived.
Groundwater
Many geologic settings in Michigan contain groundwater. The bedrock geology consists of thick sedimentary rock layers depressed near the center of the Lower Peninsula, forming a bowl-shaped basin called the Michigan Basin (Figure 5). The formations that comprise the basin were deposited in layers, with the oldest beds at the bottom. The sedimentary rocks predominantly consist of sandstone, overlaid shale, limestone and dolomite. Above nearly all bedrock in Michigan are glacial deposits that can be a source of groundwater (Figure 5).
An aquifer can provide water at significantly different rates in various locations. Water availability from Michigan's bedrock depends on the local formations. Sandstone deposits, such as the Saginaw Formation in central Michigan, generally yield more water than less permeable shales, such as the Coldwater Shale (Twenter, 1966a; 1966b). The best way to detect how much water an aquifer can transmit is to observe past pumping records. For example, the Marshall Formation, a bedrock aquifer, yields more water in the south than in the north (Figure 6), due to differences in composition and texture in the aquifer from one area to another. The availability of groundwater from glacial aquifers depends on the thickness and composition of the glacial deposit. In many areas, the glacial aquifer is the major water supply. The best water supplies are located in the sand and gravel deposits in the northwestern Lower Peninsula (Twenter, 1966a; 1966b).
Water yields from glacial aquifers also vary, depending on the composition and thickness of the deposits. The highest yields from glacial aquifers are in the central to northwestern part of the Lower Peninsula (Figure 6), which have the thickest deposits of sand and gravel outwash in the state. The areas of low groundwater yield around Saginaw Bay are due to impermeable clay deposits, while low yields in the western Upper Peninsula are caused by thin glacial deposits.
Great Lakes
The Great Lakes are the largest system of freshwater lakes in the world. They contain 95 percent of the surface freshwater in the United States and 20 percent of the world's surface freshwater. The Great Lakes were formed by glaciers during the last ice age and are relatively young (15,000 years) in geologic time. Lake Superior is the largest; it contains half the water in the Great Lakes. In addition to being important shipping routes to transport grain, iron ore, limestone, and other materials, the Great Lakes provide Michigan with a multimillion dollar sport fishery as well as one of the most popular recreational boating areas in the nation.
Water Quality
"Water quality" is an elusive term because its meaning depends on the intended use. Because most human needs require clean water, water quality can be defined by the amount of harmful or otherwise unwanted substances it contains or its suitability for an intended use. Just as the distribution and availability of water varies across the state, so does its quality. Water dissolves many substances that are found in soils, bedrock, and the atmosphere, and carries them in solution. Lakes, streams, and groundwater accumulate these substances and reflect the distinctive characteristics of their watershed's soils, geology and land use.
Human activities can also change the composition of surface runoff and groundwater. Water is vulnerable to contamination at all points of the hydrologic cycle, and all pathways that transport water can also carry pollutants. Land use activities and waste disposal practices can degrade water quality. Besides those that are ongoing, many practices of the past have left behind long lasting contamination. An increasing awareness of the problems caused by these activities has developed in recent times, and Michigan has made a commitment to cease environmental degradation and clean up problem areas where possible.
Streams
Water quality in Michigan's lakes and streams is generally very good. The inland waters of the Upper Peninsula and the northern Lower Peninsula are of excellent quality, with a few local exceptions. These waters support diverse aquatic communities and coldwater sport fisheries, indicating a healthy environment. Lakes and streams in the southern Lower Peninsula typically are of good quality and support warmwater sport fisheries. However, many rivers and lakes in this area have been affected by municipal and industrial wastewater discharges and by runoff from agricultural and urban areas. The list of water quality problems includes: nutrient enrichment, oils, heavy metals, persistent chlorinated organic compounds, and problems resulting from combined sewer overflows and soil erosion.
Surface waters have been designated for specific uses with criteria and standards that must be met. At a minimum, all waters are designated for agriculture, navigation, industrial water supply, public water supply at the point of intake, warmwater fish and other indigenous aquatic life and wildlife, or partial human body contact recreation. All waters must meet the standards for total body contact recreation from May through October, except those immediately downstream from wastewater treatment plants. Of the designated uses for surface water, total body contact and public water supply at the point of intake are the most stringent. For full body contact recreation use, standards must be met for fecal coliform bacteria, total dissolved solids, chlorides, pH, dissolved oxygen, and temperature. If a body of water is not of the quality for its designated use, it is considered to have a water quality problem.
Where in-depth analyses have been performed, the actual concentrations of certain contaminants may be known for fish populations. Those waters containing contaminated fish populations may be under a fish consumption advisory by the Michigan Department of Public Health. These advisories are listed in the Michigan Department of Natural Resources Fishing Guide that is issued with every sport fishing license purchased, and they appear in newspapers and fishing updates (MDNR, 1994a). In the guide, a limit is suggested on the number or species of fish that should be eaten from a contaminated body of water, especially for high risk groups, such as children under age six and pregnant women. Fish consumption advisories include more than 21 inland lakes and the reaches of more than 26 of Michigan's rivers, as well as certain species of fish from the Great Lakes (MDNR, 1994a).
Michigan's rivers in the Lake Superior drainage basin have very good water quality with minor exceptions. Though most of these streams support coldwater fisheries, there are localized problems associated with nutrient enrichment. New wastewater treatment facilities are expected to reduce these problems.
Rivers in the Lake Michigan basin north of the Grand River watershed are of good to excellent quality with few exceptions. At least some portion of the streams in this area support coldwater fish; the Pere Marquette and Boardman rivers are fine trout streams. Localized problems exist on the Menominee, Manistique, White, Grand, and Muskegon Rivers. South of the Grand River basin, stream quality varies and is generally best in the headwater areas. Reductions in stream quality are primarily associated with urban areas and result from the combined effects of point source discharges, sewer overflows, urban runoff and habitat alterations. In spite of these problems, some of the best smallmouth bass fishing in Michigan can be found in the upstream reaches of the Kalamazoo River.
Michigan's rivers in the Lake Huron basin north of Saginaw Bay generally have good water quality. The Au Sable River is one of the finest trout streams in the eastern United States, and portions are being considered for protection under the federal Wild and Scenic Rivers Act. Within the Saginaw River drainage basin, the headwaters of the major tributaries generally have good water quality, but quality standards for designated uses are not being met in many downstream reaches. The quality of streams in the thumb area are also not meeting designated use standards because of a variety of problems associated with nutrient enrichment, dredging, and the low relief topography of the area.
Rivers in the Lake Erie basin are generally of good quality in their headwaters. Local problems primarily occur because of point source discharges or poor agricultural practices in the downstream reaches. Rivers in this basin are generally more turbid than in other areas because of natural soil conditions. The Detroit and St. Clair rivers and the downstream reaches of the Clinton, Raisin, and Rouge rivers have been identified by the International Joint Commission as Areas of Concern.
Inland Lakes
The water quality of Michigan's inland lakes is generally good to excellent, with several outstanding lakes, including Torch and Elk lakes in Antrim County, Beatons Lake in Gogebic County, Crystal Lake in Benzie County, Golden Lake in Iron County, and Glen Lake in Leelanau County. Other high quality lakes are Gull Lake in Barry and Kalamazoo Counties, and Maceday and Union lakes in Oakland County. The Michigan Department of Natural Resources has surveyed 656 inland lakes and described 12 percent as clear, oligotrophic lakes, 62 percent as moderately productive, mesotrophic lakes, and 26 percent as nutrient enriched, eutrophic lakes. Most of the eutrophic lakes are in the southern Lower Peninsula, where agricultural, urban and residential developments are common.
Groundwater
Like surface water, the quality of groundwater varies, but most is excellent. A major factor affecting groundwater quality is the geologic composition of the aquifer. Limestone aquifers typically have hard water, while sandstone aquifers may have hard or soft water. Water quality also varies within an aquifer and, in some areas, water may contain too many minerals for domestic or public use. A naturally elevated level of lead is found in the groundwater of the northern Lower Peninsula. Natural levels of arsenic in groundwater in the thumb exceed the maximum contaminant limit for this element in drinking water. In addition, some areas of the Marshall Formation contain natural salt brine.
Though groundwater is below the surface, some human activities affect its quality. Waste disposal practices, especially in the past, have contaminated a number of aquifers. The extent to which aquifers have been contaminated has not been learned, but their vulnerability to surface contamination has been estimated based on the permeability of overlying geologic layers (Figure 7). Unconfined aquifers are those which have highly permeable overlying materials, such as sand and gravel. These are more susceptible to surface contamination than confined aquifers, which have overlying layers of relatively impermeable materials, such as clay or unfractured rock.
In 1982, the Michigan Environmental Response Act (PA 307 as amended) was passed to identify and clean up sites of environmental contamination (MERA, 1982). It is administered by the Environmental Response Division of the Michigan Department of Natural Resources (MDNR). Act 307 and its administrative rules provide for the identification, risk assessment, evaluation, and cleanup of sites of environmental contamination. The act ranks these sites according to their present condition and places more emphasis on human exposure to pollutants than does the federal Comprehensive Environmental Response, Compensation and Liability Act (Superfund) ranking system (CERCLA, 1980; SARA, 1986; MDA/MDNR, 1994). The resources affected include air, groundwater, surface water, sediment and soil. Sites of groundwater contamination are distributed throughout the state (Figure 8) but are most numerous in the southern Lower Peninsula. Most of the 2698 sites identified in the Act 307 list in 1994 involve groundwater contamination (MDNR, 1993a; 1994b). The sources are varied, resulting from both point and nonpoint pollution, with leaking underground storage tanks (LUST) making up a large proportion of the total number of sites.
Great Lakes
The Great Lakes, except for Lake Erie, are oligotrophic and have excellent water quality. Nevertheless, a number of persistent toxic chemicals, including mercury, dieldrin, PCBs, DDT, chlordane, dioxin, and furans, are present in extremely low concentrations and are routinely found in fish at most locations sampled. However, after these chemicals were banned or severely restricted in the early and mid-1970s, the levels in fish declined dramatically. This decline continued into the early 1980s, albeit at a slower rate, leveling off about 1986, with no further significant improvement (MDNR, 1993b). Moreover, further decreases are not expected because of the continued contaminant inputs from nonpoint airborne sources as well as remobilization from sediments.
Despite these generally lower contaminant levels, pollution problems continue to exist in some bays, harbors, inlets and connecting channels where rivers are depositing contaminants. The International Joint Commission (IJC) of the United States and Canada monitors the water quality of the Great Lakes under the Water Quality Agreements of 1972, 1978, and 1987 (IJC, 1987; 1988). The IJC (1991a) has identified 43 Areas of Concern where environmental quality is degraded and beneficial uses of the water and biological communities are affected adversely (Figure 9). Each state or province is responsible for preparing Remedial Action Plans for the Areas of Concern within its borders (U.S. EPA, 1985; IJC, 1991b). Michigan has developed and implemented Remedial Action Plans for the 11 Areas of Concern for which it is solely responsible and participates in three additional Areas of Concern for which it shares responsibility with the province of Ontario. Problems in the Areas of Concern include heavy metals, toxic organic compounds, contaminated sediments and fish consumption advisories.
Multiple Water Uses
The physical removal of groundwater or surface water from its source is considered to be a withdrawal water use. When the water is returned to its source, it is designated as a nonconsumptive withdrawal. A consumptive use occurs when water is not returned to its source. Water is considered to be consumed when it is no longer available to the watershed because of evaporation, transpiration, incorporation into products or crops, consumption by human beings or livestock, or is otherwise lost to the immediate water environment.
Withdrawal uses are categorized as: 1) thermoelectric power generation, 2) industrial (and mining) self-supply, 3) public supply, and 4) irrigation (Figure 10). These four categories account for over 98 percent of water withdrawn and used in Michigan. The other 2 percent are generally classified as rural water use such as homeowner wells, drinking water for livestock, and dairy sanitation.
Utilities that generate thermoelectric power (more than 90 fossil fuel and four nuclear power plants) withdraw more water than the other three uses combined (Figure 10). More than 98 percent of the water withdrawn for thermoelectric power generation is from the Great Lakes and connecting waterways. Only 1.3 percent of that water is consumed, primarily through evaporation.
Industrial self-supply is water withdrawn from waterways by a user instead of being supplied by a public source. Over 9,000 Michigan industries are in this category, using water to manufacture automobiles, steel, chemicals, plastics, pulp, and paper. About 10 percent of the water withdrawn by self-supplied industries is consumed; the remainder is returned to the watershed, often following treatment that removes contaminants or heat.
Public water supply systems provide water to homes, schools, and offices, and to industries and businesses that are not self-supplied. Water consumption for household uses is presented in Table 1. The average household uses 75 gallons of water per person per day. The average school uses between 15 and 25 gallons of water per student per day. Municipal water supply systems provide most of the public drinking water in Michigan; 80 percent of this water is withdrawn from the Great Lakes. Groundwater from private wells is the source of drinking water for about 90 percent of rural residents.
More than 3,000 irrigators withdraw water for agricultural, recreational, and commercial irrigation. Irrigation occurred in every county during 1977 (the last year for which data were available), with 325,000 acres irrigated. Agricultural irrigation accounted for 85 percent of the irrigated acreage. Recreational irrigation used 9.2 percent of the total water, primarily for golf course and park irrigation. Commercial irrigation (sod, flowers, and nurseries) accounted for 4.4 percent. Most of the water used for irrigation comes from groundwater, inland lakes and streams, accounting for about 70 percent of the water withdrawn from these sources. Through the 1970s, irrigation water use increased at a faster pace than any other category. This was especially true in southwestern Michigan, where irrigation continues to increase.
Quantities of water withdrawn and consumed from Great Lakes, groundwater, and inland surface water sources show the state's dependence on the Great Lakes as a source of supply (Figure 11). Though inland surface waters are the smallest source, almost half of the water withdrawn is consumed. Overall, however, less than 5 percent of the entire quantity of water withdrawn from all sources is consumed.
Instream uses of water do not involve withdrawing water from the source. They include such uses as navigation, hydroelectric power generation, waste assimilation, fish and wildlife habitat, and recreation. The shipping industry uses the Great Lakes for commercial navigation, moving more than 75 million short tons of goods through Michigan's ports in 1984. Hydroelectric power plants produced over 1.5 million megawatt hours of electricity in 1985, about 2.25 percent of the total power generated in the state that year. The tourism and recreation industry uses water resources to attract visitors, generating an estimated $14 billion annually. Most residents live within 10 miles of a lake or stream, and water activities are frequent pastimes. Recreational opportunities are also provided by wetlands, and include waterfowl hunting, bird watching and hiking. For more information on the importance of Michigan's water resources for fish and wildlife habitat and recreation see SAPMINR Special Reports 74, 75, 76, 77, and 78.
Though Michigan has an abundant water supply, certain areas experience deficiencies during droughts, primarily because the period of least supply occurs during the highest demand. For example, irrigation demands are highest during the summer months, when rivers are at lower flow. When river flow decreases, so does its ability to support aquatic life and to dilute and assimilate discharged wastes. At these times, multiple use conflicts are greatest.
Water Resources Management
Proper management of Michigan's water resources is essential to the state's continued prosperity and quality of life. To manage water resources efficiently, cooperation and communication among individual landowners, state, local and federal agencies, and many environmental and business organizations are necessary. Water management challenges facing Michigan include providing quality drinking water and wastewater treatment, environmental protection and repair, watershed management, water conservation, land use management, and dam inspections.
Under Michigan's system of water laws, riparian owners, property owners whose lands are adjacent to a stream or lake, have a qualified right to use the surface water without "unreasonably" diminishing either its quality or quantity. Circuit courts can decide disputes regarding water use, the protection of water resources from misuse, and enforcement of state laws regarding water. Michigan law also requires property owners to make only "reasonable use" of groundwater. The courts may also decide disputes between groundwater users when competing uses conflict. Historically, landowners have enjoyed the right to take and use water on their land and to dispose of it without permits (common law). Recent federal and Michigan laws, however, require landowners and other water users to secure a discharge permit before disposing of wastewater (statutory law).
In 1972, the Clean Water Act established the National Pollutant Discharge Elimination System (NPDES) to issue permits for every discharge of wastewater into the waters of the United States (CWA, 1972). The director of the Michigan Department of Natural Resources (MDNR) has the authority to implement NPDES permits based on the recommendations of the MDNR staff. Michigan also has surface water quality standards that meet or exceed U.S. Environmental Protection Agency (EPA) criteria. When application is made for an NPDES permit, the MDNR determines the amount of each substance that the applicant can discharge to maintain these standards. Where the water quality is better than minimum standards, degradation through discharge is not permitted. For toxic materials, discharge levels are based on toxicity tests. Discharges allowed under NPDES permits are designed so that "toxic substances shall not be present in the waters of the state at levels which are or may become injurious to the public health, safety, or welfare; plant and animal life; or the designated uses of those waters" (MWRC, 1986; Grant, 1994).
Steps have also been taken to prevent groundwater pollution. All discharges to groundwater require a permit, and discharge levels are set so that no significant degradation occurs. The Michigan Solid Waste Disposal Act and the Michigan Hazardous Waste Management Act regulate siting, design, and management of solid and hazardous waste disposal facilities.
Michigan has 79 sites on the National Priorities List of the Federal Comprehensive Environmental Response Compensation and Liability Act of 1980 (CERCLA-Superfund) program (CERCLA, 1980; SARA, 1986). These sites have been determined by the EPA to be significantly polluted enough to merit federal money for remedial action. Several have received funding for site study and development of cleanup plans, and a few are in the cleanup stage. Only two states have more sites enrolled in the Superfund program. Michigan passed "polluter pay" legislation in 1990 that assigns the financial responsibility for cleanup of contaminated sites to the parties responsible for the problem (MERA, 1982). Legislation was also passed that requires removing or replacing underground storage tanks in the state.
Water Resources: Continuing Issues
Point Source Pollution
In the last two decades, major legislation has been passed and implemented to improve water quality. The National Pollutant Discharge Elimination System (NPDES) has been very successful in eliminating pollution from point sources, such as discharge pipes (CWA, 1972). As industrial discharges into local waterways were controlled, a major, federally funded, sewage treatment plant construction program also provided most Michigan cities with not only primary and secondary but tertiary wastewater treatment. Many of these sewage treatment plants now have reached capacity and should be expanded or upgraded, or they are in need of repair and maintenance, but no federal funding has been allocated for this purpose. Consequently, increasing levels of nutrients and other substances from these sources are likely to enter the waterways. Though most discharges comply with established NPDES permit limits, increased monitoring is needed as treatment facilities become outdated in both the public and private sectors.
Nonpoint Source Pollution
Over the same time, awareness has been raised of the need to eliminate nonpoint source (NPS) pollution discharges from sources such as soil erosion and airborne toxics, as well as runoff from irrigation operations, animal feedlots and construction sites, all of which pose different and more complicated problems that are much more difficult to control. Even with the vast improvement in water quality in Michigan lakes and streams due to point source control, a number of Michigan's water bodies still do not meet water quality criteria for their designated uses because of nonpoint sources of pollution. An MDNR survey of county officials, such as drain, road and planning commissioners and local health sanitarians, showed that they believed NPS pollution continues to cause water resource problems in more than 99 percent of Michigan's watersheds (MDNR, 1988). The streams and lakes still receive pollutants from such nonpoint sources in their watersheds as agricultural lands (75%), urban lands (70%), forest lands (69%), construction sites (74%), and septic systems (81%). The water flowing through and over these sources cannot be readily collected, treated and discharged according to an NPDES permit. Therefore, while NPS pollution has been reduced in the past two decades because of soil erosion and sedimentation control programs, additional efforts should be made to better manage and control pollution from other nonpoint sources.
This trend should continue because the federal government is increasing requirements for NPS pollution control. Section 319 of the federal Water Quality Act of 1987 (WQA, 1987), which reauthorized the Clean Water Act (CWA, 1972), requires each state to identify navigable waters that are not meeting water quality standards because of NPS pollution and to develop a Nonpoint Source Management Program. NPS Management Programs must identify best management practices (BMPs) for reducing pollutant loadings and establish programs to implement them. These programs are supposed to be implemented on a watershed-by-watershed basis to the maximum extent practicable. Section 319 also provides a grant program for implementing NPS Management Programs, with the federal share of the costs not to exceed 60 percent.
Section 6217 of the Coastal Zone Act Reauthorization Amendments (CZARA, 1990) of the original Coastal Zone Management Act (CZMA, 1972) requires the EPA to publish and periodically revise specific management measures (SMMs) for sources of NPS pollution in coastal waters. These SMMs must be technologically and economically achievable management systems. States are given the responsibility of implementing SMMs in their Coastal NPS Pollution Control Programs. If a state fails to comply with these requirements, their federal grants for nonpoint source pollution control are reduced.
A coordinated strategy is needed to control NPS pollution. Because Michigan is almost entirely within the Great Lakes watershed, its Coastal Zone Management Plan must contain an integrated program that implements the EPA's specific management measures. The EPA (1993) published Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters, which describes the SMMs that must be implemented in Michigan's Coastal NPS Pollution Control Program. EPA has organized the management measures into six broad categories: agriculture, forestry, urban areas, marinas and recreational boating, hydromodification (dams, levees and shoreline erosion), and wetlands protection and biofiltration. Michigan must develop enforceable policies that will implement these SMMs throughout the state by July 1995.
Groundwater Contamination
Coordinated efforts to protect groundwater from current and potential sources of contamination must continue. Almost half of the state's urban residents and 95 percent of the rural population rely on groundwater for drinking. Though educational efforts in recent years have led to increased public awareness and concern about groundwater resources, incidents of contamination persist.
There are currently 2,698 identified Act 307 sites of environmental contamination in Michigan (MDNR, 1993a). Of these, 1,488 are confirmed groundwater contamination. Suspected groundwater contamination exists at 251 of the Act 307 sites, and 719 sites have the potential for groundwater contamination (MDNR, 1994b). In addition to the Act 307 sites, 6,741 leaking underground gasoline and fuel oil storage tanks have been identified (MDNR, 1994b). These are of particular concern because a majority of these sites are assumed to be contaminating groundwater resources.
Concerns about the state's groundwater resources have shifted over the past several years from point sources, such as unregulated dumpsites, to nonpoint sources, which now dominate groundwater quality concerns. These include contributions from agriculture, private homes and small businesses. Nitrate contamination and loadings of pesticides to groundwater are being increasingly recognized as major contributors to groundwater contamination in agricultural areas (MDNR, 1992).
The geology of the area is an important determinant of the extent of groundwater contamination. Areas of the state where unconfined aquifers are overlaid with permeable soils such as sand and gravel are most at risk of contamination, especially in densely populated and highly industrialized areas.
Though no single piece of legislation completely protects the state's groundwater resources, the Michigan Groundwater Protection Strategy and Implementation Plan, developed by the MDNR in 1989, sets general mandates and state goals on which to build groundwater protection programs. These would protect public health and the environment by preventing future degradation of groundwater and by restoring to productive use groundwater that has already been contaminated. They would also manage and protect groundwater as part of an overall water management program, recognizing the interrelationship between groundwater and surface water. In addition, these mandates, which encourage and reward groundwater protection, would create a cooperative management environment for all levels of government, business, industry and citizen organizations.
Two recent initiatives will facilitate the protection of Michigan's groundwater in future years. The first is the state's Groundwater and Freshwater Protection Act (PA 247 of 1993), which provides for the protection of groundwater from contamination by pesticides and fertilizers (MGFP, 1993). Administered by the Michigan Department of Agriculture in conjunction with other state agencies, the act will develop and promote the implementation of voluntary stewardship practices for the protection of groundwater.
The second, jointly administered by the Michigan departments of Natural Resources and Public Health, is the Michigan Wellhead Protection Program, approved by the EPA in 1994. Established in response to the 1986 amendments to the federal Safe Drinking Water Act, the program seeks to protect the estimated 15,000 public water supply systems that depend on groundwater for drinking water supplies (SDWA, 1986).
Wellhead protection is a planning and management approach designed to protect public groundwater supply systems from contamination. Potential sources of contamination within a designated area surrounding the well or well field (the wellhead protection area) are controlled or managed. Though the program is voluntary, public water supply systems may avoid costly monitoring requirements if an acceptable wellhead protection program is implemented.
Atmospheric Deposition of Pollutants
Pollutants are also reaching Michigan land and waters via short- and long-range atmospheric transport. As the more obvious sources of surface water pollution have been controlled, the transport of contaminants through the air has emerged as a more widely recognized and significant source of pollution. The most publicized atmospheric pollutant is acid rain, which is caused by the combustion of fossil fuels. Recent studies show that atmospheric transport to the Great Lakes is also an important source of mercury, nutrients, and a wide variety of chlorinated organic compounds. Mercury and some organic compounds are of concern because they persist in the environment and accumulate to harmful levels in fish and in fish-eating birds. The polychlorinated biphenyls (PCBs) are one of the most widely studied groups of chemicals that are transported through the air. PCBs were used in a variety of industrial processes until 1977, when their production was stopped. That same year, scientists discovered PCBs in rain water on Beaver Island in northeastern Lake Michigan (Murphy and Rzeszntko, 1977); and, in 1986, 70 percent of the PCB loading to Lake Superior was determined to be from the atmosphere (Eisenreich, 1987). In 1992, contaminated sediments and water in Green Bay were determined to be releasing PCBs to the atmosphere (Hornbuckle et al., 1993; Achman et al., 1993). This finding was alarming because it demonstrated that, contrary to previous thought, pollutants from past discharges could be released from sediments to water and to the atmosphere and be transported to another location. It is now evident that at least some classes of compounds, such as mercury and PCBs, can be mobilized from sediments and possibly other contaminated areas, and be transported through the atmosphere. Since many of Michigan's harbors have sediments that are contaminated from past discharges, these in-place pollutants may be sources of diminishing toxic contamination.
Pollutants are also transported to Michigan from outside the Great Lakes basin. The pesticide toxaphene is transported in air masses from the southern United States to the Great Lakes region, where it is removed from the atmosphere by rain. Other chemicals, such as mercury and DDT, are known to travel thousands of miles through the atmosphere. Atmospheric transport and deposition of contaminants is a major concern because pollution sources may be far from the area of deposition and, therefore, outside local political jurisdiction. Other sources may be in-place pollutants that have not been identified.
Air pollution abatement will ultimately have to be coordinated on a global scale to prevent atmospheric deposition of toxicants and other substances. Permit systems are effective methods of reducing the discharge of point source pollutants into the environment. To control nonpoint source pollutants, management practices on land surfaces must continue to improve. Abatement of atmospheric pollution requires international cooperation in pesticide use, pollution control permits and the remediation of in-place pollutants.
Soil Erosion
Soil erosion continues to affect Michigan's agricultural and water resources. The 1987 National Resources Inventory, conducted by the United States Department of Agriculture's Soil Conservation Service, estimated the annual loss of Michigan soil by sheet, rill and wind erosion to be 36.3 million tons (USDA, 1987). The value of nutrients in this soil exceeded $181 million. By 1987, soil erosion had increased 15 percent to 42 million tons per year with a nutrient value of $210 million. Soil erosion has, in some instances, reduced crop yields by five to 25 percent and property values by 20 percent. In an Indiana study, severe soil erosion increased production costs by $3.61/acre and reduced net income by $33.20/acre (Anon., 1984).
Agriculture is not the only source of soil erosion. Construction of roads, buildings, and subdivisions exposes soil that can be eroded by wind and rain. Harvesting forest products can also expose soil to erosion, as with building roads to remove timber. Similarly, changing the slope of the land surface can increase the runoff rates of water and result in erosion. Channel erosion can be a significant source of sediment where stream banks become unstable, especially if the vegetation has been removed.
Soil erosion has a variety of off-site impacts as well, including sedimentation in agricultural drains, streams, lakes and harbors, destruction of fish habitats, and nuisance weed and algae growth in lakes and streams. Nutrients and pesticides are carried along with soil erosion, contributing to eutrophication and, possibly, eliminating desired forms of aquatic life.
To counteract such effects, state and federal laws have been passed to control erosion. The state of Michigan passed the Soil Erosion and Sedimentation Control Act in 1972 to control erosion near lakes and streams (SESC, 1972). The act requires county governments to control with a permit system earth changes such as transportation facilities, subdivisions or lot development, industrial or commercial development, recreational facilities, utilities, water impoundments and waterway construction, and oil, gas and mineral wells. Agricultural and mining practices are exempt from this act, limiting its utility to stop NPS pollution.
The Food Security Act (Farm Bill) of 1985 introduced two programs aimed at reducing soil erosion: the Highly Erodible Land Conservation provision and the Conservation Reserve Program (FSA, 1985). These programs were renewed by the federal Agriculture, Conservation, and Trade Act of 1990 (FACT, 1990). The Highly Erodible Land Conservation provision requires farmers to follow approved conservation plans when they raise crops on highly erodible lands. If they do not, they are ineligible for federal price supports, crop insurance, disaster payments, Farmers Home Administration loans, and commodity payments. The Conservation Reserve Program pays farmers annual rent to keep highly erodible land out of production for at least 10 years and reimburses them for half the cost of establishing conservation measures on that land. The Coastal Zone Act Reauthorization Amendments (CZARA, 1990) require that Michigan enforce EPA management measures, including best management practices, to control soil erosion and other nonpoint sources of pollution. As Congress begins debate on the 1995 Farm Bill, among the issues addressed will be how to manage the Conservation Reserve Program contracts, which begin to expire in 1995.
Wetland Destruction
The debate over federal wetlands policy will continue to generate confusion and antagonism among agencies, the public, and states until needed reforms are addressed. Many reforms are included in a comprehensive package of initiatives developed by an Interagency Working Group of Federal Wetlands Policy, convened by the Clinton administration. These include: an administrative appeals process so that landowners can seek speedy recourse without having to go to court if permits are denied; a final regulation to clarify the scope of activities regulated under the Clean Water Act; a regulation ensuring that prior converted cropland will not be subject to wetland regulations; a less vigorous permit review for small projects with minor environmental impacts; agency consistency in wetlands identification; endorsement of mitigation banks; incentives for state and local units to engage in watershed planning; increased funding for the USDA's Wetland Reserve Program; and promotion of restoration of damaged wetlands through voluntary, nonregulatory programs.
While many of the reforms contained in this package, such as permit deadlines, an appeals process, and mitigation banking, were proposed by persons seeking improvements in the current regulatory program, some experts have expressed doubt about the likely effectiveness of these reforms. Mitigation banking, for example, would allow developers to destroy wetlands, provided that they either create new wetlands or restore old ones. Experts state that the concept of mitigation banking is so new that science and available technology cannot accurately predict the impacts.
Within Michigan, the MDNR has formed a Wetland Advisory Committee, supported by the EPA, to develop a statewide wetland strategy. Designed to focus on nonregulatory aspects of wetland management, the strategy will incorporate an aggressive education/outreach program, promulgation of wetland water quality standards, regulatory protection of certain critical wetlands, a wetland reclamation initiative, and overall development, coordination, and distribution of a comprehensive action strategy.
Federal, state, and local regulations to protect wetlands, prevent natural wetland conversion, and restore wetlands have generated much controversy. General trends, however, indicate that continued loss will threaten the environmental and socio-economic benefits that wetlands provide. Though reauthorization of the Clean Water Act (WQA, 1987) does not include wetlands protection, Congress is waiting for the final report from the National Academy of Sciences, due in 1994, regarding new, consistent and scientifically sound wetland definitions. The Clinton administration will offer a new perspective on wetlands management by requiring higher levels of integration and coordination among government agencies. The administration supports the goal of no overall net loss of the nation's remaining wetlands and the long-term goal of increasing the quality and quantity of the nation's wetland resource base.
Water Resources: Emerging Issues
Wastewater Treatment Needs
Michigan's public wastewater treatment infrastructure needs $3.7 billion in repairs, replacements, and improvements. Two-thirds of the state's residents are served by public wastewater treatment facilities. There are 378 of these publicly owned treatment works (POTWs), built at a cost of $4.8 billion. Nearly three-fourths of the wastewater received by these facilities undergoes primary, secondary and tertiary (phosphorus removal) treatment before being discharged to Michigan's rivers. Even with this impressive record, an additional $3.7 billion in improvements is needed to be in full compliance with the Clean Water Act. The necessary improvements are $1.6 billion in combined sewer overflow control, $1.3 billion for sewer repairs and 114 new collector and interceptor sewers, and $820 million for 72 new POTWs. No federal funding is authorized for wastewater treatment. The Construction Grants Program expired in 1990, and the State Revolving Fund expires in 1994. The Clean Water Act expired in 1992 and has not yet been reauthorized.
The Clean Water Act of 1972 and the Water Quality Act of 1987 have provided a total of $3.3 billion in federal funds to build Michigan's existing public wastewater treatment facilities. The Clean Water Act of 1972 appropriated funds for the EPA Construction Grants Program, which distributed $2.9 billion toward building POTWs (CWA, 1972). The Water Quality Act (WQA, 1987) reauthorized the Clean Water Act and replaced the Construction Grants Program with the State Revolving Fund (SRF). Under the SRF, an additional $400 million was loaned to local communities for building POTWs. The state of Michigan has contributed $1.2 billion toward the construction of these facilities, and local communities have spent $300 million. Annual operating and maintenance costs exceed $350 million and are paid by the users of the systems through local fee structures.
Additional funding for public wastewater treatment must be provided when the Clean Water Act is reauthorized in 1994 or 1995. Stormwater management, both in separated and combined sewers, is an issue of great importance for the state of Michigan and the nation. Strong federal leadership is needed to reauthorize the Clean Water Act. Greater emphasis should be placed on stormwater management and other nonpoint pollution sources. The State Revolving Fund should be refinanced and extended into the twenty-first century to ensure that Michigan continues to maintain or improve the quality of its water resources.
Irrigation Districts
The Michigan Irrigation Act allows the formation of irrigation districts in coastal counties (MIA, 1979). These irrigation districts may withdraw water from the Great Lakes to benefit crops or other agricultural operations to improve food production. Property owners within an irrigation district could, therefore, obtain Great Lakes water for agricultural irrigation without being riparian owners. An irrigation district that would withdraw water from Saginaw Bay for subirrigation of 2,000 acres has been proposed in Huron County. If approved, this would be the first irrigation district to withdraw Great Lakes waters and would set a precedent.
Subirrigation, or subsurface irrigation, involves establishing and maintaining a water table near the bottom of the crop root zone from which water flows by capillary action into the root zone. In recent years, this method of improving the soil/water environment for crop production has sparked the interest of agricultural producers. In Michigan, the greatest concentration of cropland that is suitable for subirrigation lies within the Saginaw Bay watershed, and farmers are installing subsurface tile systems for irrigation as well as drainage. However, water supplies that are suitable for irrigation are limited in the Saginaw Bay area. Not only are groundwater supplies limited, but deep wells have a high brine content and are generally unsuitable for irrigation. Irrigation withdrawals from shallow wells have caused public outrage in years of limited rainfall, as domestic wells have gone dry during droughts. Few large streams and inland lakes in this area can provide enough water for irrigation; and under Michigan's water laws, only riparian owners, those who own land adjacent to a water body, may withdraw surface water for irrigation and other uses.
There are two controversies over the proposed irrigation district. First, because most irrigation water is converted into crop production, irrigation is a consumptive use and represents a net loss of water diverted from the Great Lakes. However, these waters are a vital shipping resource for the economies of eight states in the United States and two Canadian provinces. Diversion of Great Lakes waters is being resisted because decreasing water levels would reduce the amount of cargo ships can carry, especially in the shallower connecting channels during periods of low lake levels, and so decrease commerce. Secondly, Saginaw Bay has been colonized by zebra mussels, raising concern that zebra mussel veligers (larvae) will be transported by the irrigation district and spread to inland waters.
Watershed Management Policies
Developmental policies and environmental revitalization efforts are often isolated. Development decisions are typically made for short term gains within discrete political boundaries. Land developers seek low tax burdens as well as access to markets and transportation corridors. Communities want the expanded tax base and employment opportunities that land development brings, so they offer tax incentives and infrastructure support such as sewers and roads. In contrast, people seeking to avoid crime, crowding, and high property taxes are moving to rural areas. These factors have produced a disjointed patchwork of development that consumes prime farmland, congests highways, and abandons urban centers. This pattern of development also damages water resources. Drainage patterns are changed as properties are graded to provide building sites, wetlands are filled and the soil surface is sealed with layers of concrete and asphalt. These changes may cause erosion and flooding, and decrease groundwater recharge. Rapid development may exceed the capacity of the rural wastewater treatment infrastructure; simultaneously, the exodus from urban areas erodes the funding for urban infrastructure, causing facilities to decay.
Efforts to protect and improve the environment have a similar patchwork nature. Point source pollution has been controlled through specific air, soil, and water permits; but waters are still polluted from a wide variety of nonpoint sources. Conflicting resource needs and political agendas have resulted in fragmented environmental policies that exclude certain polluters while forcing others to reduce or eliminate their discharges.
Integrated watershed management is needed to solve water resource problems. Water resources can be best protected when development decisions are made on the basis of watershed boundaries. Best management practices must be cooperatively and consistently implemented throughout a watershed. All communities, all economic sectors and all pollution sources within a watershed must be considered to protect water resources effectively. Comprehensive policies are needed that coordinate discharge permits and management practices, and also include growth management and urban redevelopment.
A coordinated watershed management program has been initiated. The Coastal Zone Act Reauthorization Amendments (CZARA, 1990) require states to execute enforceable policies that will implement management measures to control nonpoint source pollution. This directive from the federal government also requires states to coordinate nonpoint source pollution control on a watershed basis. Michigan has until July 1995 to assemble its nonpoint source pollution management plan.
In 1992, Governor John Engler requested that Michigan's environmental issues be ranked according to their relative risk. One of the highest ranking issues identified in this process was "lack of land use planning that considers ecosystems." In response to this need, the Americana Foundation published an advisory document, "Managing Growth: New Directions Toward Integrated Land Use Planning," which outlines how land use policies should be changed to protect Michigan's environment. The next century presents a truly daunting task for Michigan: incorporating the necessary development policies and environmental protection programs into a comprehensive, watershed-based land use system that respects home rule, provides opportunities for economic development, and protects the environment.
Restriction/Ban of Chlorine Compounds
The need to restrict and/or ban the use of chlorine and chlorine containing compounds as industrial feedstocks in the Great Lakes Basin was recommended by the International Joint Commission (IJC) in support of their Virtual Elimination Task Force recommendation to eliminate the inputs of persistent toxic substances into the Great Lakes Basin (IJC, 1991c). This recommendation for phasing out chlorine use was based, in part, on scientific evidence that a wide range of chlorine containing compounds are responsible for unacceptable biological effects in the Great Lakes ecosystem. It has generated much controversy, especially from industries that would prefer to have chlorine containing compounds evaluated on a compound by compound basis.
Chlorination has been the primary method for disinfecting public water supplies in the United States in the twentieth century. The primary benefit of chlorination has been the virtual elimination of major outbreaks of waterborne diseases (cholera, typhoid, and leptospirosis) in the United States and other affluent countries (Bull et al., 1990) and a general improvement in public health (Ellis, 1991). Chlorine, delivered to water as chlorine gas (Cl2), is a highly advantageous disinfectant. Chlorine in water hydrolyzes to hypochlorous acid (HOCl), which can, in turn, dissociate to hypochlorite ion (OCl-). Both forms have biocidal activity against bacteria, viruses and protozoan cysts, such as Giardia, and both are persistent enough to provide protection throughout typical water distribution systems (NRC, 1987).
The primary risk associated with chlorination of drinking waters is the formation of potentially toxic chlorinated organic compounds. Surveys of U.S. drinking water since the mid-1970s have found a wide variety of halogenated disinfection by-products (DBPs), which are produced by reaction of chlorine with organic compounds in raw waters. A variety of evidence suggests that halogenated DBPs may present a risk, specifically cancer of the urinary bladder, to consumers of chlorinated drinking water. Estimates of the average lifetime excess cancer risk attributable to consumption of chlorinated drinking water range from two (Chlorine Institute, 1993) to 110 (Bull et al., 1990) mortalities per million people. However, the health risks associated with inadequate water treatment probably greatly exceed risks associated with consumption of chlorinated drinking water. For example, in 1900, before chlorination, typhoid fever was responsible for 360 deaths/million (NRC, 1987).
While no alternative disinfectants can replace chlorination completely, several alternatives to traditional chlorination practices are available that may provide adequate disinfection while eliminating many of the health risks associated with DBPs. These alternatives include disinfectants, such as ozone, chlorine dioxide, chloramine, and ultraviolet radiation. Changes in treatment procedures can also increase the effectiveness of treatment and/or reduce the formation of DBPs.
Ozone is the most widely used alternate water disinfectant, especially in several European countries and in Quebec. Ozone is a powerful oxidant that is generally more effective than chlorine at equivalent concentrations, especially against viruses, bacterial spores, and protozoan cysts. Ozone also oxidizes organic pollutants, such as detergents, phenols, and some pesticides that produce taste, odor, and color, as well as inorganic compounds such as sulfide, cyanide, and nitrite. Unlike chlorination, ozone disinfection is relatively insensitive to the presence of ammonia and to differences in pH (Ellis, 1991). Despite its effectiveness, ozone has several disadvantages. It is among the most expensive of disinfectant techniques. Due to its high reactivity, ozone provides no residual disinfection, and its effectiveness is reduced in colored waters by reaction with humic and fulvic compounds. Though the reactivity of ozone assures that there will be no direct toxicity from ozone in drinking water, ozonation produces by-products, specifically formaldehyde and acetaldehyde, which have been shown to be animal carcinogens in inhalation studies. There have been no evaluations of the carcinogenicity of these compounds in oral exposures at the low concentrations typical of drinking water (Bull et al., 1990).
Ultraviolet radiation (UV) has a long history of use as a disinfectant for drinking water, though its use has been limited due to the effectiveness and cost-efficiency of chlorination (Ellis, 1991). The greatest advantage of UV disinfection is its lack of chemical by-products; however, like ozone, UV disinfection produces no residual effect, making it unsuitable for final disinfection. The usefulness of UV as a pre-treatment is less than ozone because it is less effective at destroying nonvolatile organic compounds (Chlorine Institute, 1993). Though UV has been reported to be an effective biocide for pathogenic and nuisance microbes, its effectiveness is lower for gram-positive bacteria, bacterial spores, algae, and some protozoans (e.g., Giardia). The effectiveness of UV disinfection is affected by the physical and chemical characteristics of the water, such as turbidity, color, iron, and organic content. The relatively low penetration of UV requires that water must be exposed in thin films, which tends to limit the cost-effective application of UV sterilization to smaller-scale drinking water systems.
Chlorine dioxide has been considered as a candidate to replace chlorine as the primary disinfectant in drinking water treatment (Myers, 1990). The disinfecting power of chlorine dioxide is approximately equal to that of chlorine and may be superior at higher pH, in colored waters, and with limited contact times. The greatest advantage of chlorine dioxide over chlorine is a reduction in the formation of haloform DBPs (Reynolds et al., 1989). Other favorable characteristics of chlorine dioxide include residual disinfection, effective precipitation of iron and manganese, and lack of reaction with ammonia. The major limitation of using chlorine dioxide is the toxicity of the parent compound and its ionization products, chlorite (ClO2-) and chlorate ions (ClO3-), which cause alterations of thyroid function, erythrocyte damage and hemolytic anemia in humans. The NRC (1987) suggested no observable effect levels (NOEL) for chlorine dioxide of 0.06 mg/l for children and 0.21 mg/l for adults. No observable effect levels for chlorite and chlorate are even lower (0.007 and 0.024 mg/l). All these "safe" concentrations are below the levels of these compounds in water disinfected with chlorine dioxide (SDWA, 1974; Bull et al., 1990).
Presently, the EPA recommends that the chlorine ban issue needs further study while Environment Canada has indicated that there is not enough scientific evidence to support the ban. In Michigan, Governor John Engler has asked the Michigan Environmental Science Board to evaluate the scientific basis for the IJC recommendation and propose options to protect the public and the Great Lakes (MDNR, 1993b). However, pending legislation, including the reauthorization of the Safe Drinking Water Act, and the IJC's recommendation to virtually eliminate toxic substances into the Great Lakes (IJC, 1991c), would impose stricter limits on drinking water by-products. Proposed regulations include limits of 80 ęg/l for trihalomethanes, 60 ęg/l for trihaloacetic acids, and 1.0 mg/l for chlorite in drinking water. They would also require the monitoring of microbial contaminants and DBPs in systems using raw surface waters containing more than 4 mg/l total organic carbon (TOC) and groundwater containing more than 2 mg/l TOC (Miller, 1993). It is estimated that these regulations will affect more than half of the drinking water systems in the United States and that costs of meeting the regulations could run as high as $1 billion (Newman, 1993). Two common approaches to maintain adequate disinfection while reducing health risks from DBPs are: 1) treat raw waters with an alternative oxidant (such as ozone) to prevent the formation of DBPs, then use chlorine to provide residual disinfection; and 2) post-treat chlorinated waters to remove DBPs.
Global and Regional Effects of Climate Change
Global climate change is probably the most important emerging environmental problem facing humanity in the 21st Century. The global average temperature has risen approximately 0.6 oC in the past century, an increase that has been attributed to increases in atmospheric "greenhouse gases" which prevent infrared radiation from the earth's surface from escaping to space. The greenhouse gases include carbon dioxide, methane, nitrous oxide, and chlorofluorcarbons (CFCs).
Based on estimates that greenhouse gas increases equivalent to a doubling of pre-industrial carbon dioxide will occur by the year 2030, global circulation models predict that global mean temperatures will increase during this period by 2 to 5 oC. This global temperature increase is expected to increase precipitation, melt glaciers and icecaps, and raise sea levels by 0.3 to 1.1 m (Smith, 1990). The oceans have the capacity to absorb both heat and carbon dioxide and slow the warming process. In fact, in recent decades, while nighttime low temperatures have increased, daytime high temperatures have actually decreased (Kukla and Karl, 1993). Global circulation models project relatively small changes in temperature near the equator and large increases in both temperature and precipitation in polar regions. In mid-latitude regions like the northern United States and southern Canada, temperature increases would be greatest during the winter, and precipitation would be increased in winter but decreased during the summer (Mohnen and Wang, 1992).
Projected climate changes would have substantial effects on all aspects of Michigan's water resources. The predictions causing greatest concern are 10 percent reductions in summer rainfall and summer temperature increases of 2 to 3 oC (Mohnen and Wang, 1992). These estimates are projected to cause 30 to 50 percent reductions in soil moisture and corresponding reductions in groundwater recharge and surface runoff. These changes will also cause increases in lake and stream tempera-tures, decreases in lake levels, and changes in the thermal structure of lakes in the summer. Changes in the temperature regimes of the Great Lakes could have both positive and negative effects on fish communities. Because lake productivity and fish growth rates generally increase with temperature, fish production and fishery yields in some areas are likely to double. Less beneficial consequences of warming would be shifts in the competitive relationships among important fish species and expansion of warmwater species into Great Lakes habitats (Meisner et al., 1987). Increases in warmwater habitat could also allow establishment or expansion of warmwater exotic species, which could prove to be as great a nuisance as the coldwater exotics that have entered the Great Lakes in the past (Magnuson et al., 1990).
Increased air temperature and decreased soil moisture may reduce the productivity of Michigan's prime agricultural belt and encourage agricultural use of more northern regions of the state (Rustem et al., 1992). Decreased stream flows and decreased precipitation in summer months may also lead to water use conflicts, especially when the same water sources are used for agricultural irrigation and municipal supplies.
Water quality effects of warming could involve both eutrophication and contaminant mobilization. Increased water temperature and changes in hydrologic regime such as lower lake levels, lower water inputs, and increased water retention times would tend to increase nutrient concentrations and primary productivity in coastal areas, embayments, and connecting channels, and to release contaminants from harbor and coastal sediments (Regier and Meisner, 1990).
Difficult and expensive policy decisions will be required to significantly reduce the release of greenhouse gases. Substantial reductions in emission rates would be necessary to stabilize atmospheric concentrations of greenhouse gases: over 60 percent for carbon dioxide, 15-20 percent for methane, 70-80 percent for nitrous oxide, and 70-85 percent for CFCs (Mohnen and Wang, 1992). The Great Lakes surrounding Michigan have moderating effects on both its temperature and precipitation patterns. Future proposals to divert water from the Great Lakes are likely, and such diversions may exacerbate natural changes in the Great Lakes caused by climatic change.
Adopting an Ecosystem Approach to Environmental Management
The term "ecosystem approach," when applied to environmental management, can have very different meanings. It implies that humans view themselves as integral parts of their ecosystem, rather than as outsiders who use their environment only as a source of resources (Vallentyne and Beeton, 1988). Despite broad agreement that ecosystem-based management should be based on ecosystem integrity, rather than simply human risks and benefits, there is less agreement about how ecosystem integrity can be measured and managed. Scientific investigations of ecosystem characteristics play several important roles in assessing ecosystem integrity, including monitoring, investigating, and predicting possible risks, determining the sustainable limits of human impacts, and restoring damaged environments (Miller, 1991). Restoration has taken a leading role in ecosystem-based management of the Great Lakes. Under the Great Lakes Water Quality Agreement, sites in the Great Lakes and connecting channels can be designated Areas of Concern when water quality conditions adversely affect aquatic organisms or impair human uses (Hartig and Zarull, 1992; IJC, 1988). Remedial Action Plans (RAPs) developed to restore these sites have become testing grounds for ecosystem-based management (MacKenzie, 1993; IJC, 1991b).
The complexity of the structure and function of ecosystems makes selecting appropriate measures of ecosystem integrity a difficult task. Ecosystem level measurements such as flows of energy, materials, and productivity may have great value for resource management (Evans, 1993). However, such integrative measures of aquatic ecosystem function may not reflect substantial changes occurring at the lower levels of organization, such as shifts in community composition and extinction of species (Schindler, 1987).
Population or community assessments have been widely used as indicators of ecosystem integrity in aquatic and terrestrial systems, including the Great Lakes. Populations of indicator species, known from historical data to be representative of unpolluted conditions, have been proposed as indicators of ecological integrity in Great Lakes habitats. The indicator species approach has advantages over the ecosystem level approach; but it is difficult to justify using trends of a single species, however dominant or ecologically important, as a valid indicator of ecosystem status. Changes at the community level in benthic invertebrates or fish can be assessed by indices which include information on species sensitivity (Karr, 1993). A more sophisticated method for community analysis uses multivariate statistical analysis to compare benthic community composition to that "expected" based on simple environmental characteristics, such as depth, water chemistry, and sediment characteristics (Reynoldson and Day, 1993). Criteria used to identify Areas of Concern in the Great Lakes include several of the above approaches, including laboratory bioassays, observations of deformities, birth defects, or reproductive problems in wildlife populations, and alterations in community structure (Hartig and Zarull, 1992; IJC, 1991a). Furthermore, ecosystem models can improve our understanding of relationships among ecosystem components, and provide predictions that can be used for setting regulations or management objectives and for estimating the impacts of management strategies.
The implementation of ecosystem-based management for the Great Lakes faces both scientific and institutional impediments. Though quantification of ecosystem integrity is a matter of scientific uncertainty, substantial progress has been made toward consensus on methods to identify relevant, measurable impacts of human activities (Hartig and Zarull, 1992). Institutional barriers remain the most serious challenge to ecosystem-based management. Despite the activities of multijurisdictional agencies and organizations, cooperation among jurisdictions is still hampered by incompatible management objectives and procedures (Vallentyne and Beeton, 1988). Some progress is evident in the development of Lakewide Management Plans and uniform criteria for toxic pollutants under the EPA's Great Lakes Initiative (Whitaker, 1993). Ecosystem-based management will also require changes in the philosophical approach of governments and resource agencies, away from the traditional, artificial resource subdivisions and toward a more holistic consideration of ecosystem values (Evans, 1993). Maintaining public support for ecosystem-based management will require a commitment to communicate the value of ecosystem integrity and to encourage shifts in public attitudes from an anthropocentric to an ecocentric world view.
Ecosystem-based management, as currently conceived and realized, has several advantages relative to traditional environmental management practices. The inter-governmental cooperation necessary for management of the Great Lakes as an ecosystem has already resulted in improved harmonization of management goals and methodologies among the federal, state, and provincial governments. Managing entire ecosystems rather than separate ecosystem components should improve our ability to understand the impacts of human actions on the Great Lakes and develop effective management strategies. Ultimately, the greatest advantage is the acknowledgment of the importance of all aspects of the Great Lakes ecosystem, rather than those that have direct socioeconomic effects on the human population. Management practices that restore and protect all ecosystem components will provide a sustainable resource base for future generations.
Ecosystem-based management will not come without increased economic costs, at least during the transition from traditional practices. The increased costs of managing Areas of Concern represent an attempt to reverse the historical commitment of Great Lakes resources to industrial uses (Harris et al., 1990). In some cases, some of these costs may be recouped through legal actions under CERCLA (Superfund) or the Natural Resource Damage Act. As degraded areas are rehabilitated, advantages from multiple beneficial uses of these areas will contribute to the overall economic readjustment occurring in the Great Lakes basin. Ultimately, the ecosystem-based approach should provide for proactive management that will limit future costs caused by human disturbance of the Great Lakes ecosystem.
Conclusion
The emerging and continuing issues in water resources demonstrate how many facets of resource management are interrelated. Water resources are ubiquitous within the global environment, within all biological processes and within industrial and agricultural processes. The constant use and reuse of water by all systems has at times reduced its suitability for certain functions and demonstrates that water must be managed properly for all biological, industrial, recreational, and other entities. One key to successful resource management for the twenty-first century and beyond is to integrate and coordinate all aspects into a comprehensive system.
This challenge is immense and critical. Failures and successes of the past have demonstrated that the wise use of resources requires a comprehensive, holistic approach. The early successes in water quality improvements centered around placing the full cost, including cleanup, on each user. Both the NPDES program and the construction of publicly owned treatment works have improved the quality of Michigan's waters. The success of these programs, however, has been limited by their scope. They changed the practices of only a few, specific water users. Nonetheless, progress continues toward water quality improvements. Wellhead protection programs and remedial action plans have broader scopes of activity than in the past, and they address larger issues besides wastewater discharge. The next steps toward comprehensive water resource management are being taken, specifically in the areas of nonpoint source pollution control plans and watershed management plans. These processes are teaching important lessons that will be useful to progress toward more comprehensive, holistic, natural resources management. Progress is already being made to promote ecosystem management, and ways are being considered to measure ecosystem quality. In the next phase, the multiple levels of political jurisdiction have to be integrated. None of these steps will be easy; however, they will all be important, even crucial to the continued survival and flourishing of many species and to the planet we call home.
Figure 1. Precipitation and runoff. Adapted from USGS, 1985 and Nurnberger, 1987.
Figure 2. Major watersheds of Michigan. Adapted from WMU, 1981.
Figure 3. August low flows in Michigan rivers (Wallace and Annable, 1987).
Figure 4. Distribution of Michigan's inland lakes.
Figure 5. Principal aquifers in Michigan.
A cross-section through the state from the northwest to the southeast shows the underlying bedrock and glacial aquifers. Starting in the center of the Lower Peninsula, traveling outward or drilling down through the basin, several formations are encountered:Glacial Deposits: Found at the surface throughout most of the state, glacial deposits can extend to depths exceeding 400 feet. These deposits consist of outwash sand and gravel, lacustrine sand, slit and clay, along with till made up of clay to boulder-size particles. Deposits with sand and gravel tend to be better aquifers than those with clay. Jurassic Red Beds: Not a principal aquifer, this bedrock formation is composed of sandstone, shale, and clay. Saginaw Formation: This important aquifer for the central Lower Peninsula consists of sandstone with interbedded shale, limestone, coal, and gypsum. The Saginaw Formation is used for rural wells and municipal supplies both in Lansing and Jackson. Michigan Formation: Not a principal aquifer, the Michigan Formation is below the Saginaw. Composed largely of shale, it does not allow water to move easily. Marshall Formation: One of the most productive aquifers in the state, this aquifer is composed of fine to medium grain sandstone and can yield high amounts of water. The Marshall Formation is used for municipal water supplies in cities such as Albion and Battle Creek. Coldwater Formation: Not a principal aquifer, the Coldwater Formation lies below the Marshall and consists mostly of shale. Silurian-Devonian: Consisting dominantly of limestone and dolomite, water in these rocks flows primarily through well-connected fractures and can have good yields. Cambrian-Ordovician: A primary source of water for the eastern Upper Peninsula, these rocks are composed of sandstone in the lower deposits with limestone and dolomite above. Precambrian Sandstone: The final aquifer is a sandstone which is well cemented and interbedded with shale. Water travels through these deposits in small fractures that are not well connected. Precambrian: Not a principal aquifer. Precambrian ingenous and metamorphic rocks lie below all of the sedimentary rocks. Adapted from USGS, 1985.
Figure 6. Bedrock and glacial aquifers (Twenter, 1966a; 1966b).
Figure 7. Aquifers at risk for surface contamination (CRS, 1989).
Figure 8. The number of Act 307 sites of environmental contamination per county (MDNR, 1993a).
Figure 9. The locations and problems at the 14 Areas of Concern in Michigan (IJC, 1991a)
Key:C = conventional pollutants, M = heavy metals, T = toxic organic substances, S = contaminated sediments, E = eutrophication, F = fish consumption advisory, I = biota impacted, B = beach closings, and A = aesthetics.
Figure 10. Uses of water withdrawn and consumed.
Table 1. Water consumption for household uses.
Activity Water Consumption
(gallons)
Laundry (Machine) 20 to 60 per load
Washing Dishes (Hand) 5 to 20 per wash
Washing Dishes (Machine) 10 to 16 per wash
Car Washing 10 to 200 per wash
Toilet 4 to 7 per flush
Leaking Faucet 2 to 300 per day
Lawn Sprinkling 5 to 10 per minute
Brushing Teeth 2 to 5 per minute
Shower 5 to 10 per minute
Tub Bath 10 to 30 per bath
Figure 11. Sources of water withdrawals.
Glossary
ABATEMENT. The method of reducing the degree or intensity of pollution; also the use of such a method.
ACCEPTABLE DAILY INTAKE (ADI). The amount of a contaminant an organism can consume each day without concern relative to ill effects. The ADI is usually one one hundredth of the no effect level for the most sensitive organism tested. See Consumption Advisory.
AIR QUALITY STANDARDS. The prescribed level of pollutants in the outside air that cannot be exceeded legally during a specified time in a specified geographical area.
ANALYSIS (VERSUS ASSESSMENT). A formal, usually quantitative, determination of the effects of an action as in risk analyses and impact analyses.
AQUIFER, ARTESIAN (OR CONFINED). An aquifer situated between layers of relatively impermeable materials (rock layers) in which groundwater under pressure greater than the atmosphere is forced to rise in wells.
AQUIFER, PERCHED. An aquifer containing unconfined (unpressurized) groundwater located above a lower body of groundwater by an unsaturated zone.
AQUITARD. An underground, saturated zone of low permeable rock, clay, or gravel that will not provide significant quantities of water to a well or spring.
AREAS OF CONCERN (AOC). Any severely polluted area in the Great Lakes Basin that fails to meet the objectives of the U.S.-Canada International Joint Commission (IJC) 1978 amendments to the 1972 Great Lakes Water Quality Agreement resulting in impairments of beneficial uses, including recreational activities, maintaining healthy aquatic life and water supplies. To date, 43 AOCs have been designated in the Great Lakes Basin, including 14 in Michigan (see Remedial Action Plan).
AROMATIC HYDROCARBONS. A class of organic compounds containing one or more benzene-type ring structures or cyclic groups. Examples include: benzene, toluene, naphthalene, and chlorobenzene.
ASSESSMENT (VERSUS ANALYSIS). The combination of analysis with policy-related activities such as identification of issues and comparison of risks and benefits as in risk assessment and impacts assessment.
ATMOSPHERIC TRANSPORT. The transport of pollutants through the atmosphere by local/regional/global winds from where they are produced to an area downwind, sometimes hundreds of miles from the sources.
BACKGROUND CONCENTRATION. The concentration of a chemical present in a medium such as air, water, or soil due to natural sources.
BASIN YIELD. The quantity of water that each square mile of watershed contributes through surface runoff and groundwater discharge to sustain a river flow during dry periods.
BED LOAD. The part of the stream's load that is rolling and sliding along because it is too heavy to be carried by suspension.
BENTHIC REGION. The bottom of a body of water. This region supports the benthos, a type of life that not only lives upon but contributes to the character of the bottom.
BENTHOS. Aquatic bottom-dwelling organisms. These include: 1) sessile animals, such as sponges, barnacles, mussels, oysters, some worms, and many attached algae; 2) creeping forms, such as insects, snails, and certain clams; and 3) burrowing forms, which include most clams and worms.
BIOACCUMULATION. The net accumulation of a chemical in the tissues of an organism as a result of uptake from all routes of exposure. Chemicals that bioaccumulate are most often halogenated organics, which are very soluble in lipids (fats) and are resistant to biological degradation.
BIOCHEMICAL OXYGEN DEMAND (BOD). The amount of oxygen consumed in the biological processes that break down organic matter in water. Large amounts of organic waste use up large amounts of dissolved oxygen. Thus, the greater the degree of pollution, the higher the BOD.
BIOCONCENTRATION. The net accumulation of a chemical directly from aqueous solution by an aquatic organism.
BIODEGRADATION. The breakdown of complex chemical constituents into simple components through the biological processes of naturally occurring organisms. Buffer. The mixture of soluble weak acids and their salts in most lakes and streams. It is able to minimize changes in pH from the inputs of acids or bases.
BUFFER CAPACITY. The amount of acid or base that must be added to a lake or stream to produce a unit change in pH.
CARCINOGEN. Any substance or agent that produces or induces the development of cancer.
CERCLA. Comprehensive Environmental Response, Compensation, and Liability Act, passed by Congress in 1980 and administered by the U.S. Environmental Protection Agency.
CHLORINATED HYDROCARBONS. Organic compounds containing carbon, hydrogen, and chlorine atoms. This type of compound includes many pesticides and PCBs.
COASTAL ZONE. Coastal waters and adjacent lands that exert a measurable influence on the sea and its ecology.
COMBINED SEWERS. A sewerage system that carries both sanitary sewage and storm water runoff. During dry weather, combined sewers carry all wastewater to the treatment plant. During a storm, only part of the flow is intercepted because of plant overloading; the remainder goes untreated to the receiving stream.
CONE OF DEPRESSION. A depression in the water table or potentiometric surface that has the shape of an inverted cone and develops around a well from which water is being withdrawn.
CONSUMPTION ADVISORY. A risk management technique used to reduce exposure to contaminated food, especially fish. A government agency recommends that fish from certain bodies of water not be eaten because they contain potentially harmful concentrations of toxicants.
CULTURAL EUTROPHICATION. Acceleration of the natural aging process of bodies of water through the direct intervention of human beings.
DENITRIFICATION. The bacterial reduction of nitrate (NO3-) or nitrite (NO2-) to gaseous molecular nitrogen (N2), and nitrogen oxides such as NO2, N2O, and NO. This occurs under anaerobic conditions and results in a loss of nitrogen from the surface soil environment to the atmosphere.
DEPURATION. The loss of a chemical compound from an organism due to degradation and/or elimination.
DETRITUS. Dead organic matter and its associated microbial elements; usually finely divided, settleable, particulate organic matter (POM) or dissolved organic matter (DOM).
DISSOLVED OXYGEN (DO). The oxygen dissolved in water or sewage. Adequately dissolved oxygen is necessary for the life of fish and other aquatic organisms and for the prevention of offensive odors. Low dissolved oxygen concentrations generally are due to the discharge of excessive quantities of organic solids with high BOD, the result of inadequate waste treatment.
ECOLOGICAL RISK ANALYSIS. Determination of the probability and magnitude of adverse effects of environmental hazards (e.g., chemical, physical, or biological agents occurring in or mediated by the ambient environment) on nonhuman biota. See Ecological Risk Assessment and Environmental Risk Analysis.
ECOLOGICAL RISK ASSESSMENT. The process of defining and quantifying risks to nonhuman biota and determining the acceptability of those risks. See Ecological Risk Analysis. EMISSION STANDARD. The maximum quantity of a pollutant legally permitted to be discharged from a single source, either mobile or stationary.
ENVIRONMENTAL IMPACT ASSESSMENT. A type of assessment that attempts to reveal the consequences of proposed governmental and/or private actions that may significantly affect the quality of the environment. In the United States, such assessments are required of federal agencies by the National Environmental Policy Act of 1970 as an aid to governmental decision making. Some state governments in the United States as well as some other national governments have similar requirements.
ENVIRONMENTAL RISK ANALYSIS. Determination of the probability of adverse effects on human beings and nonhuman biota resulting from an environmental hazard (e.g., a chemical, physical, or biological agent occurring in or mediated by the environment).
ENVIRONMENTAL TRANSPORT. The movement of contaminants from their point of release through various media to locations where deposition or exposure to organisms occurs.
EPILIMNION. The upper, well-mixed, well-illuminated, nearly isothermal layer of a stratified, holomictic lake that does not have a permanent thermal stratification.
ESCHERICHIA COLI (E. Coli). One of the coliform groups of bacteria that live in the intestinal tract of warm-blooded animals; often used as an indicator of animal and human fecal contamination of water.
EUTROPHIC LAKES. Shallow lakes, weed-choked at the edges and very rich in nutrients. The water is characterized by large amounts of algae, low water transparency, low dissolved oxygen, and high BOD.
FEN. A low-lying land area partly covered by water.
HALOGENATED HYDROCARBONS. Organic compounds, both aliphatic and aromatic, in which some hydrogen atoms have been replaced by fluorine, chlorine, bromine or iodine atoms. See Chlorinated Hydrocarbons.
HYDROLOGIC CYCLE. The continuous circulation of water among the oceans, the atmosphere, and the earth in the form of precipitation, runoff, percolation, evapotranspiration, and stream discharge.
HYPOLIMNION. The poorly illuminated deep layer of denser cold water lying below the thermocline (metalimnion) of a directly stratified lake. See Epilimnion. IMPERMEABLE LAYER. A formation of geologic material with a low hydraulic conductivity that allows little or no water to infiltrate through it.
LIMITING FACTOR. Any influence or material which tends to slow growth and productivity in an ecosystem; either too many or too few of these critical factors may limit biological production.
LITTORAL. The marginal region of a body of water; the shallow, near-shore region; often defined by the band from zero depth to the outer edge of the rooted plants.
MAXIMUM CONTAMINANT Level (MCL). The highest concentration of a contaminant permissible in a public water supply, as specified in the national Primary Drinking Water Standards established under the Safe Drinking Water Act (SDWA).
MESOTROPHY. The condition of water being only moderately rich in plant nutrients and, hence, of limited organic production.
METALIMNION. The zone of rapid temperature change in a stratified lake.
MUTAGEN. Any substance or agent that produces or induces permanent change in the genetic material of an organism by altering its DNA.
NITRIFICATION. A microbiological mediated oxidation process that converts ammonia to nitrite ions and nitrite ions to nitrate ions.
NATIONAL PRIORITY LIST (NPL). The U.S. EPA list of uncontrolled hazardous waste sites eligible for cleanup under CERCLA (Superfund).
NO OBSERVED EFFECT LEVEL (NOEL). The highest dose of a chemical/toxicant that can be administered to a specific animal species without producing an observable adverse effect.
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES). A permitting program required by the 1972 amendments to the Water Quality Act of 1965 to eliminate and/or control the discharge of pollutants from point sources, such as factories.
OLIGOTROPHIC LAKES. Cold water lakes with very little or no organic production. The water is characterized by the absence of significant plant or algae growth, high water transparency, high dissolved oxygen, and low BOD.
ORGANIC COMPOUNDS. Natural or synthetic compounds with a carbon base, with the exception of inorganic carbon compounds such as carbon dioxide (CO2), bicarbonates (HCO3-), and carbonates (CO3-).
OZONE (O3). A pungent, colorless, toxic gas. Ozone is used as a disinfectant in water treatment. It is also one component of photochemical smog and is considered to be a major air pollutant.
POLYNUCLEAR AROMATIC HYDROCARBONS (PAH). A large group of multi-ring aromatic organic compounds, some of which are priority pollutants. Found naturally in heavy petroleum residues, such as tars, and produced by burning organic materials.
POLYCHLORINATED BIPHENYL (PCB). One of 209 fire resistant compounds with the molecular formula C12HnCl10-n, where n = 0-9, PCBs are widely used in industrial applications. PCBs exhibit many of the same characteristics as DDT and may, therefore, be confused with that pesticide. PCBs are highly toxic to aquatic life, they persist in the environment for long periods of time, and they are biologically accumulative.
PERIPHYTON. The biota attached to submersed surfaces; community of sessile organisms on lake and stream substrata.
PERCHED WATER. Unconfined groundwater held above the water table by a layer of impermeable rock or sediment; usually cannot produce significant amounts of water.
PERSISTENCE. A measure of the time needed to reduce the quantity of a pollutant concentration by 50 percent. Compounds that require long periods of time to be degraded by chemical and/or biological means are called persistent.
PHOTOLYSIS. Chemical decomposition or dissociation by the action of light or near visible electromagnetic radiation. Photolysis reactions are important in the degradation/conversion of air and waterborne pollutants.
PHYTOTOXICITY. Pertaining to the property of killing or injuring higher plants or plant parts. Pore Water. Water that occupies open spaces between solid soil and sediment particles. Also called interstitial water.
PRIMARY PRODUCTION. The production of organic matter from inorganic materials by autotrophic organisms with the help of radiant energy.
PRIORITY POLLUTANTS. A group of approximately 130 chemicals (about 100 are organics) on a U.S. EPA list because they are toxic and relatively common in industrial discharges.
RCRA. Resource Conservation and Recovery Act, passed by Congress in 1976 and administered by the U.S. EPA.
REMEDIAL ACTION PLAN (RAP). A plan for implementing the clean-up of a contaminated site. Specifically for the Areas of Concern in the Great Lakes Basin, the plan must embody a comprehensive ecosystem approach to restore and protect the beneficial uses in severely polluted areas.
RESIDENCE TIME. The time needed for a molecule of water to travel through a system. For groundwater, the time required to travel through the aquifer from a point of recharge to a point of discharge; for surface water, the time required for the inflow to replace the volume of the lake or watercourse.
RESOURCE RECOVERY. The process of obtaining materials or energy, particularly from solid waste.
RISK. The probability of an undesired effect. If the level of effect is treated as an integer variable, risk is the product of the probability and frequency of effect (e.g., probability of an accident x the number of expected mortalities).
SATURATED ZONE. The portion of subsurface soil and rock where every available space is filled with water. Aquifers are located in this zone.
SDWA. Safe Drinking Water Act, passed by Congress in 1974 and administered by the U.S. EPA.
SORPTION. The combined effect of adsorption and absorption resulting in the net removal of dissolved substances by particles.
SUPERFUND. See CERCLA.
TERATOGEN. Any substance or agent that, if taken by the mother, produces or induces abnormalities in a developing organism, resulting in either fetal death or congenital abnormality.
THRESHOLD. The level of poison intake which produces clinically detectable effects. This is not necessarily the level below which no damage is done.
TOTAL DISSOLVED SOLIDS (TDS). Filtrable residue; usually expressed as g/liter or mg/liter following evaporation of a measured sample of filtered water.
TOXAPHENE. An insecticidal clorinated camphene which exists as a mixture. More than 170 individual compounds are represented by the empirical formula C10H10Cl8. The many compounds found in the formulations of toxaphene vary widely in their toxicity.
TOXICANT. Any substance in water, wastewater, or runoff that kills or injures an organism through its chemical or physical action or by altering its environment.
TROPHIC LEVEL. The nutritional level of an organism in a community based on its feeding requirements. Phytoplankton are at the first level; zooplankton are at the second.
TURBIDITY. A measure of water cloudiness due to suspended and colloidal organic and inorganic matter.
UNCONFINED AQUIFER. An aquifer with the water table as its upper boundary. Because the aquifer is not u