The Water Management Plan identified the need for revisions to existing City ordinances regarding Storm Water Management.  The City Council adopted a new Storm Water Management Ordinance on April 9, 2002.  The general purpose of this ordinance is to accommodate anticipated community development and land use practices, while controlling the quality and quantity of storm water runoff, and properly managing and protecting ground water resources as well as the physical habitat of the Kinnickinnic River and its tributaries, and set forth storm water management and erosion control standards which apply to all land development and land disturbing activities.

Since 1982, City of River Falls ordinances have regulated rainfall events up to the 6", 100-year, 24-hour design storm, which have a 1% probability of happening in a given year.  Our current ordinance requires runoff from 2, 10, and 100-year events to be captured and controlled such that the rate of storm water discharge does not exceed pre-development conditions.  This follows the guidelines for quantity discharge as published in the Wisconsin Storm Water Manual which was created by the Wisconsin Department of Natural Resources and the University of Wisconsin-Madison. Ironically, newly adopted Wisconsin DNR rules regarding runoff management (NR151) only regulate the 2-year, 24-hour design storm.  

Published information by Schueler, Pitt and other national storm water experts indicate that the first flush of storm water runoff carries the pollutants from impervious surfaces typical of urban areas. 

The Wisconsin Storm Water Manual states:

"It is well-established that relatively small storms are responsible for the majority of the annual pollutant loads in urban runoff (Schueler, 1987; Pitt, 1989; Roesner, 1991) and that the runoff volume is the critical determinant of pollutant loading and control (Pitt, 1989).  Therefore, management practices designed for water quality control need to adequately treat these frequent, relatively small storms.”

The Wisconsin Storm Water Manual goes on to cite:

"Studies in the Midwestern United States have shown that 90% of the average annual rainfall depth is produced from rains equal to or less than about 1 inch (Roesner, L., et al, 1991; Pitt, R., 1991).  Practices that encourage infiltration of storm water from these numerous small rainfall events may also effectively improve water quality." 

The City of River Falls has chosen to adopt an even higher threshold in its new Storm Water Ordinance.  It requires infiltration of additional runoff generated by a 1.5 inch event.  On top of that, standards adopted under the ordinance require a safety factor of two be used in designing infiltration areas.  The result is that infiltration basins, at the time of acceptance by the City, will be able to infiltrate twice the additional runoff generated by a 1.5 inch event.

Ordinance 5-22-07

Management Standards

Permit Application Form

Changes to Ordinance and Standards from 9-27-05 version to 5-22-07 version:
Changes to Ordinance
Changes to Standards

WDNR Technical Standards:
Erosion and Sediment Control

Storm Water Management

WI Administrative Code:
NR 151

NR 216

Other Resources: