These outdated septic systems, most of which were installed between the 1920s and 1960s, still dump raw sewage into the rivers and lakes Iowans enjoy everyday. As a result, outdated septic systems continue to pollute surface water, groundwater, and water wells throughout the state.

"Replacing outdated septic systems with approved onsite systems helps prevent further pollution of surface water, groundwater, and water wells in Iowa," said Don Hagen, coordinator of the Silver Lake Water Quality Project.

Upgraded onsite wastewater treatment systems called "onsite systems," differ from outdated septic systems in that they include both a septic tank and a secondary wastewater treatment system. The secondary treatment system, such as a soil absorption leachfield, adequately treats wastewater by destroying harmful bacteria and viruses and be reducing human waste loads before discharging it to the environment.

Since upgrading to an approved onsite system may cost $3,000 or more, some homeowners may need financial assistance to help pay for the investment. To address this problem, the DNR is working with lenders across the state to offer low-interest loans to private homeowners who need to upgrade or replace their failing septic system. Lenders issue the loans at interest rates of 3 percent or less, for amounts starting at $2,000, for a maximum repayment period of 10 years.

"The objective of our project is simple - to leave soil and sediment on the land where it belongs and out of Silver Lake," said Don Hagen, who is coordinating the project. "We look forward to working with landowners to help them keep valuable topsoil on their land and to help make our lake cleaner."

Soil reaching the lake can cause problems, as pollutants like phosphorus attach to soil and create an increase in algae blooms and a decrease in water clarity. This sediment washes in from the watershed, or area of land that drains into the lake. Over several years, lake and water depth have declined, and wave action has stirred up the sediment, making the water murky.

In the following years, the Silver Lake Watershed Project will partner with residents in the watershed to implement conservation practices such as wetlands, filter strips, permanent grass seeding and waterways that will help keep soil and pollutants from reaching the lake. Participating producers and landowners may be eligible for funding assistance through state cost share, the Conservation Reserve Program (CRP), or the Iowa Department of Natural Resources' nonpoint source grant program, funded by a U.S. Environmental Protection Agency grant.