Stormwater Program Information

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Municipal Separate Storm Sewer System (MS4)

Stormwater Management

What is Stormwater?

Stormwater is the water that runs off impervious surfaces from rain, snow melt, and surface drainage. Impervious surfaces are hard surfaces where water is unable to soak, or infiltrate, into the ground. Impervious surfaces include paved streets, parking lots, roof tops, and other hard surfaces. Significantly compacted yards can act as an impervious surface too. This water drains overland collecting sediment, litter, nutrients, and other pollutants. The stormwater then discharges into the creeks and basins in Ankeny untreated.

Stormwater Hotline: (515) 963-3520

Why Do We Manage Stormwater?

The City of Ankeny is required by the Iowa Department of Natural Resources (IDNR) to have a National Pollutant Discharge Elimination System (NPDES) Permit. This permit regulates the management of stormwater in Ankeny.

Unmanaged stormwater can cause water pollution, stream bank erosion, and flooding. As the City continues to grow and add more homes and businesses, less precipitation can infiltrate into the ground and more stormwater runoff is generated. By slowing down the stormwater through Best Management Practices (BMPs), the pollutants have a chance to settle out. These practices can help improve the water quality of our streams and basins and help improve the water quality downstream in our state's rivers.

There are six minimum measures that guide our stormwater program. They include: public education and outreach; public involvement and participation; illicit discharge detection and elimination; construction site stormwater runoff control; post-construction stormwater management; and pollution prevention/good housekeeping.  These are described in more detail below.

Public Education and Outreach

The City of Ankeny has a public education and outreach program to inform our citizens about the impacts of stormwater discharges and the measures we all can take to reduce pollutants in stormwater runoff. During rain events or snow melt, excess fertilizer, lawn clippings, trash, eroded soil, oil deposits, or other pollutants find their way into the storm sewer system and into local streams and basins. The City is working to protect our waterways and promote good stewardship of our land, water, and to help our downstream neighbors.

Our storm drains lead directly to our water bodies untreated! Remember, only rain in the drain.

Helpful Homeowner Habits

Many of our daily activities can impact the quality of our water bodies. There are many easy ways to prevent stormwater pollution.

Litter and Pet Waste

Keep litter, yard waste, and debris out of street gutters and storm drains. Pick up pet waste. Please remember anything that gets on our streets usually ends up down the drain during the next rainfall.

Lawn Fertilizer and Chemicals

Apply lawn and any other garden chemicals sparingly and according to the directions. Make sure your fertilizers are phosphorous free. Our soils have plenty of naturally occurring phosphorous. Phosphorous is usually only needed when trying to establish a new yard. Excess amounts contribute to algal blooms and oxygen deficiency in our water bodies.

Chemical Disposal

Don't dump anything in a storm drain! Household hazardous wastes can be disposed of at the Regional Collection Center in Bondurant. Other nonhazardous items can be disposed of through your garbage provider.

Soil Erosion

Bare spots in your yard, within a drainage swale, or along a creek can lose soil, adding sediment to our water bodies. Control erosion by planting ground cover and stabilizing erosion-prone areas.

Septic Systems

Most Ankeny residents are connected to the sanitary sewer system, but there are still a few that have septic systems.  Make sure that your septic system is properly maintained and functioning correctly. Have your septic system inspected and pumped every three to five years.

Detergents and Cleaners

Look for environmentally-friendly detergents and cleaners that are low in or have no phosphorous. This helps reduce the amount of nutrients discharged into our streams and basins.

Car Washing

Wash your car at a car wash where the dirty water goes into the sanitary sewer to be treated. If you do wash your car at home, wash it in a grassy area and pick low phosphorous detergent options. 

Water Management

Divert gutters off driveways and sidewalks and into vegetated areas to allow water a chance to infiltrate into the soil. Only water your grass and plants as needed, don’t overwater.

What else can I do?

The goal is to keep the rain where it falls. Want to learn more ways to improve stormwater through actions you can complete at home? Here are a few:

Native Planting

Plant deep-rooted native vegetation that adds water storing capacity to the soil and beauty to your yard. Native plants are adapted to our Iowa weather and require little watering once established. They also provide habitat for our birds, bees, and butterflies.

Soil Quality Restoration

Improve your soil quality by aerating and adding compost to your turf grass or garden areas. This helps to increase the organic matter content which allows deeper root growth for improved soils. Better soils allow more water to infiltrate into the ground and not run off your yard.

Rain Barrels

Collect water to use on your yard, garden, and potted plants. Equipped with screens to keep pests out, rain barrels keep roof water out of our storm sewer system.

Rain Gardens

A beautiful and functional garden that pools/holds water for a brief time, 12 to 24 hours, and then slowly allows that water to infiltrate into the soil.

Pervious Pavement Systems

Used instead of traditional pavement, these materials are porous allowing water to pass through and be stored below the surface. This includes pavers and concrete and asphalt systems.

Additional Homeowner Resources 

Stormwater Hotline: (515) 963-3520

Below are some articles regarding stormwater.

Below are websites with more information about stormwater practices around your home.

Below are agencies to help provide additional information about stormwater.

Public Involvement and Participation

Public involvement and participation is an important aspect of the stormwater program. One way we include the public is by the ongoing work of the Ankeny Water Quality Improvement and Stormwater Education (WISE) Group. The group was established in 2005 to work with residents concerned about stormwater and provide a community perspective to Ankeny's stormwater program. The group consists of citizens from the community with a variety of backgrounds.

Annual Stream/Watershed Cleanup

Each year we host a stream/watershed cleanup in April in conjunction with Earth Day.  The clean-up location varies each year, so check out the calendar to see where it will be held!  The City provides trash bags and vinyl gloves. Boots or shoes you don't mind getting wet or dirty are advised and please bring your own water bottle. Events are held between 8 a.m. and 11 a.m.

Volunteers can make an incredible difference to our water quality! Removing litter from your storm sewer intake or participating in a watershed cleanup can really help. You can also host your own cleanup. The City can provide bags and gloves and pick up the refuse when you are finished.

If you would like to find out more information about stormwater activities, host a cleanup, or join the Ankeny Water Quality Improvement and Stormwater Education (WISE) Group, please email Amy Bryant at or call (515) 963-3542.

Illicit Discharge Detection and Elimination

An illicit discharge is any release into the storm sewer system that is not comprised entirely of stormwater. Illicit discharges may be a result of industrial activity, deposits of oil on parking lots, excess lawn fertilizer and yard clippings, or a variety of other sources which pollute water with turbidity, excess nutrients, and bacteria. Illicit discharges can also be from failing septic systems or improperly connected sewer lines. Dumping liquids or putting any refuse into storm drain inlets is also considered an illicit discharge and eliminating these discharges is an important step in protecting Ankeny's waterways.

The City of Ankeny has adopted an illicit discharge detection and elimination (IDDE) program, which is mandated by the Municipal Separate Storm Sewer System (MS4) Permit from the Iowa DNR. Under the MS4 Permit, Ankeny is required to adopt an illicit discharge prohibition ordinance, sample discharge from storm sewers, and map the storm sewer system.

To detect illicit discharges, inspections of the outfalls are completed. An outfall is where stormwater is drained from a pipe or drainage way into a creek or water body. Each outfall is inspected a minimum of once every five years or more frequently as needed. Samples of suspected illicit discharge are collected and a reconnaissance of the outfall is performed. Once a problem is identified, the source will be determined. The responsible party will be notified and be required to eliminate and mitigate the discharge.

What are some illicit discharges and how can I prevent them?

Examples of Illicit Discharges:
  • Septic Tank effluent
  • Improper oil disposal
  • Grass clippings/leaves left in the street
  • Commercial car wash wastewater
  • Sanitary wastewater
Examples of Allowed Discharges:
  • Lawn-watering/irrigation
  • Street washing/sweeping
  • Water line flushing
  • Residential car washing
  • Any activity with a NPDES discharge permit

The best ways to keep illicit discharges from occurring is to follow good housekeeping practices. This includes recycling or properly disposing of waste, keeping waste receptacle lids secured on windy days, and cleaning up spills or litter immediately. It is important to keep grass clippings and leaves off the street. Another way to help is to keep your neighborhood storm drains clean of debris and litter.

Report illicit discharges:

While the City of Ankeny has established the IDDE Program, community involvement is a key component to the program's success. If you see any illegal dumping or signs of illicit discharge in surrounding waterways, please contact us at the following numbers:

  • Stormwater Hotline: (515) 963-3520
  • After Hours (Polk County Dispatch): (515) 286-3333
  • Iowa Department of Natural Resources Field Office #5: (515) 725-0268
  • Iowa Department of Natural Resources Emergency Spill Hotline: (515) 281-8694

Construction Site Stormwater Runoff Control

COSESCO Ordinance

The City has adopted an ordinance that requires proper soil erosion and sediment control on all sites for which a NPDES permit is required. This is mandated by the MS4 Permit from the Iowa DNR and must be enforced by the City. The ordinance addresses waste at construction sites that may adversely impact water quality and includes building materials, concrete truck washout, chemicals, solid waste, and sanitary waste. The ordinance gives the City authority to issue stop work orders if permit holders are not compliant with terms of their NPDES General Permit Number 2. A copy of the ordinance is below. 

Construction Site Review and Inspection Program

The IDNR NPDES General Permit Number 2 and Ankeny’s MS4 permit require that all construction activities greater than one acre develop a Storm Water Pollution Prevention Plan (SWPPP) in order to minimize the amount of erosion coming off each site.

The City is mandated by the MS4 permit to inspect Ankeny construction sites and see that they comply with NPDES General Permit No. 2 and other state and local regulations.  Each of these sites are inspected by the City at least once each calendar quarter. 

Financial Assurance for Erosion Control

The City requires that a performance bond for erosion control be posted for each subdivision plat.

Post-Construction Stormwater Management

Improving Water Quality Through Quality Design

This measure emphasizes the reduction or elimination of pollutants that may come from post-construction runoff after new development and redevelopment projects. The term post-construction is used to describe runoff from a site with impermeable surfaces, such as buildings, roads, and parking lots that remain after construction ends. If unchecked, increased impervious surfaces associated with development will increase stormwater volume and degrade water quality, which can harm our streams and basins.

The best way to mitigate stormwater impacts from development is to use practices to treat, store, and infiltrate runoff on-site before it can impact downstream water bodies. By requiring site designs that reduce imperviousness, increase infiltration, and provide water volume storage, water quantity and water quality can be improved.

This is achieved through the following actions:

Enforce a Post-Construction Site Runoff Control Policy Ordinance

This addresses control of runoff from building activities after construction is complete. This includes the promotion of stormwater detention and retention, grass swales, bioretention swales, riparian buffers and proper operation and maintenance of these facilities. 

Implement Site Plan Review of Post-Construction Runoff Controls

This implements procedures and acceptance criteria for review of controls for NPDES-permitted construction sites.

Inspect Runoff Control Devices

This addresses inspection and review of stormwater control devices and structures for proper maintenance. It includes providing educational material to landowners.

Implement a Watershed Assessment Program and Comprehensive Land Use Plan

This outlines the measures to be implemented which reduce flooding, reduce erosion in ditches and streams, improve water quality and reduce degradation of habitat for fish and wildlife.

Pollution Prevention/Good Housekeeping

Leading By Example

As part of the requirements from the Iowa DNR, the City has to make sure that it too follows pollution prevention and good housekeeping practices in its operations. We have implemented an operation and maintenance program that prevents or reduces pollutant runoff from municipal operations. We continue to complete this by:

Providing operation and maintenance of storm sewers including street sweeping and inspection of infrastructure.

Typical maintenance activities include routine storm sewer inspections, removal of sediment and debris, reconstruction of pipe and inlet/outlet structures, vegetation control, and erosion control. The City only maintains public infrastructure. Private facilities, including storm sewers, detention basins, and streams located on private property are not maintained by the City.

Having a pesticide and fertilizer management program.

This program was developed to reduce the amount of pollutants discharged from storage, application, and disposal of pesticides, and fertilizers. In addition, these chemicals are only applied by personnel that are properly trained in management techniques.

Training municipal employees to reduce pollutants in stormwater.

Municipal employees participate in training that addresses MS4 maintenance and reduction and prevention of stormwater pollution. Some of these areas include: park and open space maintenance; fleet and building maintenance; proper use, storage, and disposal of chemicals; new construction and land disturbance; and stormwater system maintenance.

Assessing best management practices (BMPs) at City facilities to reduce stormwater from the facilities.

Existing facilities are periodically evaluated to determine if there are any BMP retrofit opportunities to reduce the quantity of stormwater and the amount of potential pollutants leaving the site.

During new facility construction, BMPs are always considered for stormwater management.

Annual Report

An annual report is prepared and submitted to the Iowa DNR.  Below is the most recent annual report.