Welcome to Johnson County, IA

Stormwater Management

About Stormwater

Stormwater runoff is rainfall or snow melt that runs off impervious (hard) surfaces such as roads, buildings, and compacted soils. This runoff is collected and conveyed through stormwater systems (usually pipes), or flows as surface runoff directly into our streams, rivers and lakes without being treated.

Impacts of Stormwater Runoff

Stormwater can pose a risk to our water resources. Pollutants (e.g., sediment, nitrates and bacteria) accumulate on impervious surfaces between rainfalls. Runoff from rain then washes these pollutants into streams, rivers and lakes, negatively impacting water quality. Stormwater runoff can also adversely affect infrastructure and environmentally sensitive areas, as well as increase both localized and regional flooding. Johnson County requires the management of stormwater runoff through both practices that allow more rainfall to infiltrate into the ground or store and slowly release captured runoff.

Application of Regulations

Who is subject to Johnson County Stormwater Management Requirements?

If you are submitting a development application for a subdivision or site plan, or an application for a Conditional Use Permit, then you are likely subject to Subchapter 8:3.6. of the Johnson County Unified Development Ordinance.

Development Applications for Subdivisions and Site Plans

All development applications for preliminary, combined, or final plat, and Site Plan review are subject to the Stormwater Management regulations and must submit a full stormwater management plan in accordance with Chapter 8:3.6. of the Johnson County Unified Development Ordinance at time of application.

All stormwater facilities shall be installed in accordance with the approved preliminary plat, prior to approval of the final plat.

Permits for Conditionally Permitted Uses

Conditionally permitted uses for which compliance with the stormwater management regulations is required either as a condition of approval or as required in accordance with subsection 8:1.23, must have an approved stormwater management plan in accordance with Chapter 8:3.6 of the Johnson County Unified Development Ordinance plan prior to any site work commencing.

All stormwater facilities shall be installed in accordance with the approved plan prior to issuance of any Certificate of Occupancy.

View Stormwater Management Plan Submittal Guidelines and Checklist

Request for Waiver of Requirements

Stormwater Management requirements may be waived if certain conditions listed in chapter 8:3.6 are satisfied. Requests must be made prior to filing a development application, and the approved waiver must be included as part of the application materials with the development application.

Download a Stormwater Management Waiver Request Form

Stormwater Quality Improvement Plan (SWQIP)

Residential subdivisions which propose no more than one additional buildable lot may be eligible to defer stormwater management planning until time of future building permit. A waiver request form must be submitted to request deferral. Those developments for which deferral of stormwater management to time of building permit application has been approved, and propose less than 5,000 square feet of impervious rooftop, will submit a Stormwater Quality Improvement Plan (SWQIP) to fulfill stormwater requirements. SWQIPs are intended to balance traditional stormwater approaches with preservation of sensitive areas and physical site characteristics that naturally lend to stormwater runoff reduction and water quality protection.

Download a Stormwater Quality Improvement Plan Form

For More Information or to Report A Concern

Contact: Kasey Hutchinson, Soil and Water Conservation Coordinator

Phone: 319-356-6083

Email: [email protected]

Johnson County Administration Building
Planning, Development and Sustainability
913 S Dubuque Street
Iowa City, IA 52240

Additional Information

Resources for Residents
Stormwater Management at Johnson County Facilities