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Everyone lives in a watershed. A watershed is the area of land that catches rain and snow and drains or seeps into a marsh, stream, river, lake or groundwater.  The Raccoon and Des Moines Rivers are used to provide drinking water to more than 500,000 Central Iowans. Upstream land use practices – agricultural and urban – have a direct effect on water quality and quantity for downstream users. All Iowans should Think Downstream and consider how they can help make Iowa’s water safe for drinking and recreation. 

Watershed Frequently Asked Questions

A watershed is an area of land that drains into a river, lake, stream, pond, or other body of water. It includes the waterway itself and the entire land area that drains into it. For example, the watershed of a lake includes any streams emptying into the lake and the land area that drains into those streams. A watershed can be small, like a backyard puddle, or large, such as Lake Michigan.

Water is one of our most precious resources, and we depend upon it for our life. Many factors can affect our water. In order to ensure that enough drinking water is available to meet our present and future needs, it is important that we all do our part to protect our drinking water sources and to reduce water waste and pollution.

The Raccoon and Des Moines River water is treated to provide drinking water for more than 500,000 people in Des Moines and all or parts of many surrounding communities. Water from the Raccoon and Des Moines Rivers are economic drivers that benefit Central Iowa by providing abundant sources of water to business and industry. They are a source of recreation for people who canoe, kayak, and fish on our water trails. They get people outdoors to walk, run, or bike on our land trails. Wildlife depends on the rivers for food and shelter. We all depend on a healthy watershed.

The type of land use – agricultural or urban – and what we as humans do on the land have a direct impact on water quality and quantity in the watershed. A healthy watershed is necessary for a healthy environment and economy. We are all responsible for preserving and protecting our watersheds.

Whatever we do on the land or on the water can impact water quality within the Des Moines and Raccoon River watersheds. Together, land and water make a watershed, a whole system. The more contaminated the system the more it costs to retrieve, treat and deliver drinking water to our customers.

High nitrate levels are a concern in drinking water because nitrate can cause mehtemoglobienemia or blue baby syndrome, a condition found especially in infants less than six months of age. The stomach acid of an infant is not as strong as in older children or adults. This causes an increase in bacteria that can readily convert nitrate to nitrite, which competes with red blood cells for oxygen. Infants should not drink water that exceeds 10 mg/L 'nitrate-nitrogen.' This includes baby formula preparation. The Center for Disease Control warns that, “Heating or boiling your water will not remove nitrate and because some of the water will evaporate during the boiling process, the nitrate levels of water can actually increase slightly in concentration.

Nitrate and phosphorus are nutrients and can promote blooms of harmful algae and cyanobacteria. The organisms created can cause an unpleasant taste and odor to treated drinking water and may produce substances known to be toxic to humans and animals.

Cyanobacteria, formerly referred to as blue-green algae, are found naturally in lakes, rivers, ponds, and other surface water. When certain conditions exist, such as in warm water containing an abundance of nitrogen and phosphorus, they can rapidly form harmful algal blooms (HABs). HABs can have negative impacts on the ecosystem, human and animal health and on the economy. Some HABs are capable of producing toxins, called cyanotoxins such as microcystin, which can harm humans and animals.

HABs producing cyanotoxins can occur in water used as sources of drinking water. If not removed during drinking water treatment, exposure to cyanotoxins in tap water above certain levels could be harmful to humans. Drinking water containing cyanotoxins at levels exceeding the U.S. Environmental Protection Agency’s national drinking water Health Advisories can put you at risk of various adverse health effects including upset stomach, vomiting and diarrhea, as well as liver and kidney damage.

Since 2016, DMWW’s laboratory staff has used special instrumentation to test river water and finished drinking water for traces of cyanotoxins. Levels are monitored closely, and if a level of concern or advisory were detected, the public would be notified through communication methods and drinking water advisories.  If cyanotoxins are detected in raw source water, treatment is adjusted to address the contamination to try to prevent advisory levels from occurring. Extreme drought and water quality conditions in the Raccoon River have forced Des Moines Water Works at times to utilize more of the Des Moines River, which tests more predominately for cyanotoxins. During the summers of 2019 and 2020, the Des Moines River was contaminated by cyanotoxins making it an undesirable water source for more than 110 consecutive days each year.

Keeping lakes, rivers and other source waters free from manure, soil, and farm chemicals in DMWW’s agricultural watersheds is key to DMWW’s ability to provide safe, affordable drinking water to its customers. Reducing the amount of nitrogen and phosphorus in sources of drinking water can reduce the risks of HABs and the potential of cyanotoxins in source water. Decreasing the amount of farm chemicals that make their way into rivers and streams will improve surface water quality and make it less costly to treat the water.

Bacteria are easily removed and killed during water treatment. However, unnaturally high levels of bacteria can indicate increased amounts of human or animal waste in the river, stream or lake, and is a sign of an unhealthy watershed system, and can be an indicator that other organisms are present.

It takes 7-10 times the amount of chlorine to counteract ammonia in source waters. This presents multiple problems including; increased use of chlorine, difficulty maintaining adequate disinfection levels, objectionable tastes and odors and elevated levels of disinfection byproducts. Disinfection by-products are formed when chemical disinfectants react in the water with natural organic matter (natural organic matter originates from the breakdown of plants and animal waste in the soil).

DMWW’s state certified laboratory monitors water at the source, during treatment, and in the distribution system.  In addition to routine monitoring, DMWW monitors and conducts research on emerging contaminants to ensure we continually provide public health protection by providing safe drinking water.

You can help protect your source of drinking water by carefully managing the activities in or near the Raccoon and Des Moines Rivers including smaller tributaries like the Beaver or Four Mile Creeks or as small as a waterway, storm sewer, or tile line in your neighborhood or backyard. Some things you can do are:

  • Form or join a watershed association such as the Raccoon River Watershed Association or Iowa Rivers Revival. Join or encourage your neighborhood association to identify water resource improvement and protection goals and objectives.
  • Develop a water garden in your yard and in your neighborhood. Identify places where bio-swales can be installed. When rain falls on natural areas such as a yard or park it is slowed down, filtered by soil and plants, and allowed to soak back into the ground. When rain falls on impervious surfaces such as rooftops, roads, parking lots and driveways, rain does not soak into the ground and storm water runoff is created. Stormwater runoff picks up pollution such as fertilizer, pesticides, sediment, motor oil, litter, pet and yard waste.
  • Select pervious surfaces (allows for water to soak in) for walkways and driveways to increase filtration through the soil and decrease surface runoff to storm drains.
  • Dispose of all human and pet waste properly. Never dispose of waste into ditches, rivers, lakes or wooded areas. Waste contains bacteria and parasites, as well as organic matter and nutrients, notably nitrogen and phosphorous. These can contaminant the watershed and eventually leach into your drinking water source.
  • If you live near a water source and have a septic system, make sure your septic system is annually inspected and maintained so it is in good operating condition. Failing septic systems can be another source of nitrates in rivers, streams, and lakes. Never dispose of human or pet waste directly into a water source.
  • Recycle used oil and antifreeze by taking them to a local service station or recycling center. Never dispose used oil and antifreeze down a storm drain!
  • Keep your car tuned-up to reduce the deposition of toxic pollutants and petroleum by-products from exhaust gases.
  • Use care in adding fuel to watercraft to not spill gasoline or oil into the lake or river.
  • Do not attempt to dispose of hazardous waste, cleaners, used oil, or other harmful products into streets or sewers. Visit the Metro Hazardous Waste Drop-off or participate in hazardous waste disposal days in your neighborhood.
  • Landscape with native plants. They require less water, fertilizer, and pesticides.
  • Test your soil before applying fertilizers to achieve proper application levels and minimize nutrient run-off into rivers, streams, and lakes. Keep fertilizer off sidewalks and driveways to prevent rain from washing the nutrients into storm drains. If you use a professional lawn care service, select a company that follow practices designed to apply fertilizers and pesticides sparingly and properly.
  • Have a conversation with your family and friends in agricultural areas of Iowa to explain the importance of using Best Management Practices to prevent the transport of animal waste, fertilizers, and pesticides to the rivers and streams that provide you and other Iowans with drinking water.

Source Water Assessment Program

Des Moines Water Works’ (DMWW) Source Water Assessment project allowed us to increase efforts to protect the Raccoon and Des Moines Rivers at the local level by encouraging and involving key people within our communities. This project also fulfilled the requirements of the Safe Drinking Water Act (SDWA) Amendments of 1996 for state source water delineation and assessment.

The three components of the project included delineation, contaminant inventory, and susceptibility analysis. Delineation consisted of determining the boundaries for the watersheds draining into the Raccoon and Des Moines Rivers. For DMWW, our watershed delineations are above the intake structures (where the water enters the treatment process) for both rivers. A contaminant inventory consisted of identifying possible sources of contamination located within the watersheds, while the susceptibility analysis determined which of the possible sources of contamination are most likely to pollute our water sources and reach the intake structures. By preventing contamination from reaching our intakes, we will be better able to treat the water to provide you with better quality water, and save treatment costs.

Delineation identifies the topographic (the surface features of a place or region) area of the entire watershed upstream of DMWW’s intake structure. It is the area of land that catches rain and snow and drains into a stream, river, or lake, that forms our watershed and supplies our source water.

The Raccoon and Des Moines Rivers are the primary sources of water used to treat for your drinking water. These are the 2 watershed areas delineated.

Contamination can come from a variety of sources. One type is point sources, sources that can be pinpointed to one location and generally is discharged through a piping system, such as business and industries and waste water treatment facilities like the Waste Water Reclamation Authority in Des Moines. These are considered potential sources of contamination because they can release contaminants into the watershed and our source water.

Another type of contaminant is called a non-point source. These are sources not specific to one location. These types of sources may include land run-off and erosion. The Raccoon and Des Moines River watersheds are approximately 80-85% agricultural land, this is land that has been extensively tiled. Tiling systems are used to move water away from where it lands as quickly as possible. Even though these systems will discharge directly to a river or stream through a pipe they are considered non-point sources and are not regulated.

Susceptibility analyses were completed as part of the Source Water Assessment project. These analyses made susceptibility determinations based on the potential for DMWW to draw water contaminated by inventoried potential sources at concentrations that could cause concern. These determinations took into consideration any long-term impact that contaminants from inventoried potential sources may have on our source water. In addition, the watersheds that were most closely analyzed included areas having a 72-hour time of travel upstream from our intake structures and that were located within 1320 feet of a waterway.
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