Rock County Municipal Storm Water Management Plan

View the 2020 Annual Report

The County of Rock was authorized by the Department of Natural Resources on November 13, 2006 to discharge stormwater from the County owned Municipal Separate Storm Sewer Systems (MS4) in the Urbanized Area of Rock County under a Wisconsin Pollutant Discharge Elimination System (WPDES) general permit. Polluted stormwater runoff is commonly transported through MS4s, from which it is often discharged untreated into local waterbodies. An MS4 is a conveyance or system of conveyances that is:

  • Owned by a state, city, town, village, or other public entity that discharges to waters of the U.S.
  • Designed or used to collect or convey stormwater (including storm drains, pipes, ditches, etc.);
  • Not a combined sewer; and
  • Not part of a Publicly Owned Treatment Works (sewage treatment plant).

For the County, this consists of conveyance systems (ditches or curb and gutter) associated with County Highways within the Urbanized Area, as determined by population density based on the 2000 census.

View County Highways that fall into this category.

The Census Bureau created maps indicating the current boundaries of the Urbanized Areas of Janesville and Beloit based on the 2010 Census.

Each regulated MS4 operator is required to develop and implement a stormwater management program to reduce the contamination of stormwater runoff and prohibit illicit discharges. This program is intended, at minimum, to be implemented in the County’s permitted area, i.e. the areas of land under the jurisdiction of the County that drain into a MS4. Areas excluded from permit coverage, and thus from this plan, are agricultural facilities and practices, industrial or land disturbing construction activities that require separate WPDES permit coverage and storm water discharges that do not enter the County’s MS4. The County's WPDES MS4 general permit outlines certain minimum programs and documentation that must be developed to maintain compliance with the permit conditions of approval. The minimum program elements are:

  • Public Education and Outreach
  • Public Involvement and Participation
  • Illicit Discharge Detection and Elimination
  • Construction Site Pollution Control
  • Post-Construction Storm Water Management
  • Pollution Prevention

Information regarding these six programs may be found below and on the EPA Website.