Polk County Conservation

Water Quality

Ninety percent of Iowans say water quality is their number one environmental concern.

Water pollution is broken down into two types.

Non-point source pollution (NPSP) refers to pollutants that come from a widespread area and cannot be tracked to a single point or source. Soil erosion, chemical runoff, and animal waste pollution are examples NPSP. NPSP is Iowa’s major water quality problem by sheer volume and in terms of current and future economic costs to the state.

Point source pollution (PSP) – also known as “the end of the pipe pollution” – can be traced to a specific source, such as a leaking chemical tank, effluents coming from a waste treatment or industrial plant, or a manure spill from a hog confinement lagoon.

In Iowa, the number one source of surface water pollution by volume is soil erosion. Soil erodes into nearby streams, rivers, and lakes, causing many problems. The causes of soil erosion are numerous. Row crop farming, planting crops too close to rivers and streams without the benefits of filterstrips, and allowing grazing livestock access to waterways are primary sources of soil erosion, but erosion is not limited to agriculture. Road construction and building sites in towns are often sources of heavy runoff.

Easter Lake in Polk County has had problems with water quality in the past. With recent construction in the area, soil erosion has caused the water to become cloudy, making it difficult for predator fish to hunt while the added sediment has smothered fish eggs. It has been estimated that one construction site lost more than 100 tons of soil into the lake. The cost of dredging the lake and removing the sediment is over $1.2 million. The city of Des Moines and Polk County have spent thousands of dollars building sediment ponds to reduce the amount of soil that enters the water.

Another water quality concern at Easter Lake has been de-icing chemicals used at the Des Moines Airport. These chemicals are biodegradable, but in the process of breaking down use large amounts of oxygen and often cause fish kills in Yeader Creek which empties into the lake. Trash entering the lake from Yeader Creek has also been a concern. To reduce the amount of trash, a rack has been built on Yeader Creek in Ewing Park.

You can see we have many water quality concerns in the state. We all need to do our part to keep our water healthy for people and wildlife.


The Polk County Water and Land Legacy bond referendum (passed in 2012) has provided us with the necessary funding to undertake many significant water quality improvement projects since its inception.

In part, this bond has allowed Polk County Conservation to start an ambient stream water monitoring program to help assess watershed quality in Polk County. Monitoring began on October 1, 2015. Regular monitoring should be able to detect changes to water quality in the future.

Click here to see an overview flyer about the program.


  • EPA.gov - Lots of information about water and water quality

Contact Us

Administration Office
12130 NW 128th St
Granger, IA 50109

P: (515) 323-5300
F: (515) 323-5354

Monday – Friday, 8:00 a.m. – 4:30 p.m.

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