Stormwater Management

The City of Norwalk considers successful storm water management a critical element in keeping the community clean, beautiful and safe. Norwalk storm water management works to improve the quality of storm water being discharged into the local waterways. The information shown below provides details on Norwalk’s Municipal Separate Storm Sewer System (MS4) Permit as required by the Iowa Department of Natural Resources (IDNR).

Iowa Department of Natural Resources (IDNR) defines stormwater as: “The rainfall or snowmelt that runs off permeable surfaces or impervious surfaces like roads, buildings, sidewalks or compacted ground surfaces. Stormwater can flow directly to streams and lakes or it may be transported by municipal storm drain systems. Unlike sanitary sewers, storm sewers do not lead to treatment plants, but drain directly into our streams and lakes.”

“As communities grow, they often experience more stormwater runoff problems due to their increasing impervious surface areas. Rainfall and snowmelt that would normally infiltrate into the soil becomes runoff. This increases both the volume and rate of runoff, which leads to flooding, streambank erosion, and potential damages to public and private property and water quality.”

Stormwater Homeowner Grant Program
The City of Norwalk is accepting applications for its Stormwater Homeowner Grant program for projects that exhibit stormwater benefits on private properties in the City.  The application and guidelines for the program can be found at the link below.  Applications will be reviewed on a first-come first serve basis and are eligible for a reimbursement of up to 50% of a project's cost to a maximum of $1,500.  Applications are reviewed by the Community Development Department and then recommended for funding by the Stormwater Advisory Committee.  The next round of reviews will be conducted in January.  All applications for funding in this fiscal year (2022) must be received by March 31st, and projects must be completed no later than June 1st.

Application & Guidelines

Stormwater Advisory Committee
The City of Norwalk maintains a Public Utility Advisory Committee which acts as the Stormwater Advisory Committee composed of local residents with varying professions and backgrounds. The Committee is intended to provide a community perspective on public utility and stormwater issues and meet monthly to attempt to accomplish goals the group sets forth.

Erosion control on construction sites is a key component to a successful stormwater management program. Construction sites can often be areas where sediment discharge and stormwater pollution take place. Proper site stabilization and stormwater management practices are critical to eliminate the discharge of sediment and pollutants from these sites.

The Iowa Department of Natural Resources (IDNR) NPDES Permit and the City of Norwalk’s Municipal Separate Storm Sewer System (MS4) permit both require that all construction activity over one acre create and maintain a Stormwater Pollution Prevention Plan. The City of Norwalk is mandated by the MS4 to inspect Norwalk construction sites and ensure that they comply with the required state and local requirements.

Norwalk SWPPP Inspection Checklist

To report a stormwater concern, please fill out the form below.  A staff member will be in contact with you regarding your report.

Available Stormwater Informational Brochures

Concrete Washout BMPs
DNR Disposal Guides
Hazardous Waste Collection Centers
ISWEP Certified Lawn Care Provider Program
Native Turf Info
Pollution Prevention for Homeowners
Protecting Iowa's Water Quality
Rainwater Harvesting
Soil Quality Restoration
Store Pesticides Safely
SWPPP Keys to Pollution Prevention

Urban Storm Water Retrofit BMP's
Common Sense Conservation
A Common Storm Water Management Misconception
The Art to "SMART" Development
A New Storm Water Paradigm
Watersheds 101
NPDES Permit General Permit
Illicit Discharge Ordinance

Construction Site & Erosion Control Resources
Statewide Urban Design Standards and Specifications (SUDAS)

IDNR Stormwater Website

Construction Site Topsoil Requirements
On all construction sites that disturb 1 acre or more and on all residential lots that are part of a larger development the depth of topsoil that remains on the surface after the ground is stabilized must be at least as great as the depth before development took place.  Homeowners in developments platted after 10/1/2012 may call the City if they believe they have little or no topsoil on their lot.

Questions regarding the NPDES permit should be directed to IDNR Stormwater Coordinator at 515-725-8417

IDNR District 5 Field Office (Des Moines): 515-725-0268

Construction Site and Erosion Control Training Events
The Urban Connection
Iowa Association of Municipal Utilities

Contact Us
Development Services Staff
Stormwater Hotline: 515.981.9530

As the City of Norwalk continues to grow and develop, so do the amount of impervious surfaces i.e. Streets, parking lots, sidewalks, and buildings. During rain and thaw events, deposits of pollutants, soils, chemicals, etc. end up in to the storm sewer system and local waterways. It is of the utmost importance to the City of Norwalk to eliminate as much of these discharges as possible to ensure a clean environment.

Homeowner Tips & Guidelines
Litter and Pet Waste: Keep litter, pet waste, leaves, and debris out of street gutters and storm drains--these outlets drain directly to lakes, streams, rivers, and wetlands.

Oil and other Household Chemicals: Dispose of used oil, antifreeze, paint, and other household chemicals properly, not in storm sewers or drains. Clean up spilled brake fluid, oil, grease, and antifreeze. Do not hose them into the street where they can eventually reach local streams and lakes. Household hazardous wastes can be taken to the Regional Collection Center for Household Hazardous Waste in Bondurant (515-967-5512). Take Marshalltown exit north off of I-80 just east of Des Moines, go 1 mile north on Hwy 65, it is the building on the left side of the road with the green roof.

Soil: Control soil erosion on your property by planting ground cover and stabilizing erosion-prone areas.

Septic Systems: Have your septic system inspected and pumped, at a minimum, every three to five years so that it operates properly.


Useful Links