Bacteriological contamination of inland lakes

by Len Jenkins, originally posted on January 25, 2017


The many beautiful lakes in Branch and Hillsdale counties provide excellent recreational opportunities for swimming and fishing. There are also potential homesites on some of these lakes. In the past, people built their homes in lakeside locations where a municipal sewer system was not available yet building took place anyway because on-site, subsurface septic systems could be installed. This is still the case today and standards for engineering proper on-site sewage disposal systems are higher than ever before. Lots have to be large enough to contain enough area for a properly sized field bed and a replacement area. Isolation distances from wells, surface water, lot boundaries, tributaries, the seasonal high water table, or areas susceptible to flooding must be maintained. In areas with impermeable clay soil, installation of subsurface disposal systems should not take place at all unless proper site modification takes place. This usually involves backfilling with about four feet of sand through which the wastewater could percolate.

The inland lakes are deteriorating because of e-coli (coliform) entering the water from failed on-site disposal systems. This bacteria which enters the water is a threat to public health and stimulates algae blooms and aquatic plants which eventually “choke” a lake. The effluent which contains the bacteria is essentially a fertilizer. There are many old failing field-beds which were installed before good environmental standards were specified in county sanitary codes.

If you have any concerns about the water quality of a lake you swim in or live near, you can get a bacteriological analysis of that particular lake by having your local health department collect and analyze a sample. Coliform contamination of lakes is occurring all over the country where failing septic systems are common. If you find that the lake is contaminated with coliform which makes the water unsafe for skin contact, you can stop swimming in the water. You should also support efforts to require that the failed systems are repaired or replaced.

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