Dean Solomon District Natural Resources Agent and Eckhart Dersch Professor of Resource Development Michigan State University If you live on shoreline property, maintaining your septic system requires more care and work than maintaining similar systems located in other places. That's because soil and water conditions near the shoreline may make the system less efficient in treating waste, which could, in turn, cause harmful pollutants to get into your lake, stream or pond. This bulletin is designed to help shoreline property owners understand what they can do to effectively maintain their septic systems while preserving the quality of their lake, stream or pond and the health of their families. These tips are best used in conjunction with Extension bulletin E- 1521, "Maintaining Your Septic System." How Septic Systems Work in Shoreline Property Areas The purposes of a septic system are to effectively accept and treat liquid wastes from your house and to prevent biological and nutrient contaminants from getting into your well or nearby lakes and streams. Most of this treatment happens in the soil below the absorption field. The physical and chemical properties of the soils combine with microscopic organisms to decompose or prevent movement of contaminants. In soil not saturated with water, biological contaminants (bacteria and viruses) are usually absorbed and rendered inactive within a few feet of the streams absorption field. Some nutrients, on the other hand, can travel much greater distances, depending on the type of soil, the amount and concentration of waste, and the age of the system. Loam and clay soils, for example, have a greater long-term ability to absorb nutrients and prevent them from moving through the soil than do sand and muck soils. In their journey, nutrients or biological contaminants that encounter soil saturated with water can move much greater distances - in some instances, as much as several hundred feet.

Because septic systems on shoreline property are often close to the water and are sometimes saturated during high water periods, they are very likely to leak wastes to lakes and streams. Also, when shorelines erode, the distance between the septic system and the shoreline gets shorter and shorter, making it more likely that liquid waste could move horizontally through the soil to the bank and then quickly over the surface to the water. This pollution can happen even though your system appears to be working well and complies with local health department codes. Effects of Septic System Wastes on Lakes and Streams Nutrients (especially phosphorus) from leaky septic systems play a major role in causing excessive weed and algae growth in lakes and ponds. Just a small amount of additional phosphorus in a lake or pond can make a huge difference in the amount of aquatic weeds that grow during the spring and summer. Excessive weed growth, in turn, affects the ability of fish to grow and could even result in large fish kills in summer or winter. Too many weeds also make the water less enjoyable to use because of weed-tangled boat motors, weedy swimming areas, etc. Liquid wastes from your septic system that reach the water increase the chance that swimmers near your shore could catch a variety of diseases and ailments, that are associated with these wastes. How to Tell if Contaminants are Reaching the Water Look for these symptoms to tell if waste from your system is reaching surface water: Excessive weed or algae growth in the water near your shore. Phosphorus leaking from septic systems could be a major cause of this type of growth. Other factors, such as a combination of shallow water and a lake bottom rich in organic marter, or sediment and lawn fertilizer runoff, could also lead to this type of problem. Septic systems, however, are often prime suspects as sources of these pollutants.