Iowa DNR

Water Quality Assessments

Impaired Waters List

ADBNet Documentation

Assessment Process

Lakes and stretches of streams and rivers in Iowa each have specific designations, based on what they are used for—recreation, such as swimming or fishing; drinking water; or maintaining a healthy population of fish and other aquatic life. Every two years, Iowa must report on its progress in meeting water quality goals to the U.S. Environmental Protection Agency. The state prepares a report, called the 305(b) assessment, that shows how well Iowa waters are meeting those goals. The report includes waters that meet the designated uses, waters that we need more information about and waters that are impaired.

Preparation of Iowa’s integrated report includes the following basic steps:
  • Assemble all existing and readily available water quality-related data and information not previously used for 305(b) water quality assessments;
  • Identify water quality-related data and information of sufficient quality and quantity for purposes of developing scientifically defensible water quality assessments;
  • Compare these water quality-related data and information to state water quality standards to determine the degree to which assessed segments meet these standards;
  • Identify Section 303(d) impairments that are based on water quality-related data and information that meet the state’s requirements for data quantity and data quality;
  • Place all segments into one of the five categories specified in U.S. EPA’s “integrated report” guidance for water quality assessment and listing;
  • Prepare the state list of segments in need of further investigation as required by state law;
  • Prioritize the waterbody segments on the draft Section 303(d) list (Category 5) for TMDL development;
  • Provide the draft integrated report, including the draft Section 303(d) list (Category 5), to the public for review and comment;
  • Revise and finalize the integrated report based on new information and public input;
  • Submit the final integrated report, including the Section 303(d) list, to U.S. EPA for approval/disapproval

Current and previous Integrated Report methodology documents can be found on the Publications page.

This page was created 5/26/2020 10:44:44 AM and was last updated 6/8/2020 2:44:06 PM