Stormwater runoff is rainfall or snowmelt 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
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.
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.
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.
Stormwater Quality Improvement Plan (SWQIP)
Residential subdivisions which propose no more than one buildable lot may be eligible to defer stormwater management planning until time of 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). SWQIPs are intended to balance traditional stormwater quality improvements with preservation of sensitive areas and physical site characteristics that naturally lend to stormwater runoff reduction and water quality protection.
For More Information or to Report A Concern
Contact: Kasey Hutchinson, Soil and Water Conservation Coordinator
Email: [email protected]
Johnson County Administration Building
Planning, Development and Sustainability
913 S Dubuque Street
Iowa City, IA 52240