Department of
Environmental Quality

Every two years, DEQ is required by the federal Clean Water Act (CWA) to conduct a comprehensive analysis of Idaho's water bodies to determine whether they meet state water quality standards and support beneficial uses or if additional pollution controls are needed. This analysis is summarized in an "Integrated Water Quality Monitoring and Assessment Report" (Integrated Report).

The Integrated Report is submitted to the U.S. Environmental Protection Agency (EPA) for approval and made available to the public. The report serves as a guide for developing and implementing water quality improvement plans (TMDLs) to protect water quality and achieve federal and state water quality standards. An Integrated Report must be approved by the EPA before it can be used by a state to guide its management decisions.

Idaho's most recent approved version is its 2010 Integrated Report. This document will guide DEQ’s water quality management decisions until a 2012 Integrated Report is completed by DEQ and approved by EPA.

Purposes of the Integrated Report

The Integrated Report serves the following three functions:

• It is a reporting requirement of the Clean Water Act—DEQ must prepare an Integrated Report to be in compliance with federal law. It satisfies the requirements of CWA sections 305(b) and 303(d) by listing the current conditions of all state waters (required by §305(b)) and those waters that are impaired and needing a total maximum daily load (TMDL) (required by §303(d)).
• It provides the public the opportunity to learn about and comment on the status of all of Idaho's waters.
• It compiles environmental data and information from all components of DEQ's surface water quality program, as well as from other agencies, organizations, and individuals, which gives water quality managers a comprehensive look at the relative quality of all of Idaho's water bodies and helps them to set priorities and allocate resources accordingly.

Organization of the Integrated Report

The main body of the Integrated Report is a discussion of the principles and policies used to compile the report and the assessment methods used to evaluate water quality data. Appendices include schedules for TMDL development that reflect the priority ranking of waters needing a TMDL, maps showing the status of all Idaho waters, DEQ’s response to public comments, and any other relevant supporting information for the Integrated Report. The appendices also contain the lists showing the classification of all state waters into at least one of five different categories. Following the category lists is a list of assessment unit-cause combinations approved by EPA to be delisted.

Category 1: Waters of the State Wholly within Designated Wilderness or Inventoried Roadless Area Where Standards are Presumed to be Attained

Category 1 waters are wholly within a designated wilderness or inventoried roadless area where water quality standards are presumed to be attained for all beneficial uses. The only distinction between Category 1 and Category 2 waters is the wilderness and roadless status of the waters in Category 1.

Category 2: Waters of the State Attaining Some Standards

Category 2 waters fully support those beneficial uses that have been assessed. For those water bodies, no existing or readily available data or information indicated a need for a change in the beneficial uses support status.

Category 3: Waters of the State with Insufficient Data and Information to Determine if Any Standards are Attained

Category 3 waters have insufficient data or information to indicate an impairment of beneficial uses and to determine if standards have been attained. Category 3 is meant to be temporary until sufficient data and information are obtained to support a designated use attainment determination. However, in Idaho a water may remain in Category 3 under any of the following circumstances: 1) the stream has no flow when visited by DEQ (i.e., is intermittent); 2) access to the monitoring site was denied; or 3) the monitoring site is inaccessible. When DEQ encounters any of these circumstances, every attempt will be made in subsequent years to collect sufficient data and information to support a designated use attainment determination for these waters.

Category 4: Waters of the State Impaired for One or More Beneficial Uses but Not Requiring the Development of a Total Maximum Daily Load

Category 4 water bodies are grouped into one of three subcategories:

• Category 4a: TMDL completed and approved by EPA.
• Category 4b: Waters that have pollution control requirements in place, other than a TMDL, and are expected to meet standards within a reasonable period of time.
• Category 4c: Water bodies impaired by pollution (e.g., flow alteration and habitat alteration) but not pollutants. According to EPA, water bodies impaired by pollution do not require development of a TMDL.

Category 5: Waters of the State for Which a TMDL is Needed

Impaired water bodies that do not meet applicable water quality standards for one or more beneficial uses by one or more pollutants are placed in Category 5. Category 5 is a streamlined §303(d) list that excludes waters that have an EPA-approved TMDL (Category 4a) and waters impaired by pollution (Category 4c), such as flow alteration or habitat modification. Waters can only be removed from Category 5 by having either an EPA-approved TMDL or EPA approval to remove based on good cause.

In some cases, a water body may be classified in more than one category. If the water is impaired or if water quality standards are not being met, an assessment unit may show up in both Category 4 and 5. Most occurrences of such multiple listings are for water bodies that are impaired for multiple pollutants or pollution (e.g., flow or habitat alteration). For example, if a water body is impaired by a pollutant (e.g., temperature) and pollution (e.g., flow alteration), then the water body would be listed in Category 5 for temperature and Category 4c for flow alteration.

2010 Integrated Report

The 2010 Integrated Report was completed and submitted for EPA approval in August 2011. The report was approved by EPA in September 2011.

• EPA Approval Letter - September 29, 2011

The 2010 Integrated Report presents the principles and policies used by DEQ to compile the report, the categorized lists showing the current status of all state waters, and all supporting information, including maps showing the status of all Idaho waters.

Highlights of the 2010 Integrated Report

• The format of the report has changed. All information is now included in one document, including DEQ’s response to comments and statewide maps.
• Since the 2008 Integrated Report, 523 new assessment units (AUs) have been added as a result of new lake AUs, AU splits, and AUs that had beneficial uses not fully supporting but no causes associated with them, which prevented them from being captured in the Integrated Report.
• DEQ delisted 354 assessment unit-cause combinations in the 2010 Integrated Report.
• DEQ and the U.S. Forest Service completed the state’s first justification for Category 4b listings for Bear Valley Creek and Elk Creek. Four AUs impaired by sediment were placed in Category 4b.
• The report includes a discussion about Category 4b policies and procedures in the body of the document.
• DEQ proposed a new policy for handling tribal waters in the 2012 Integrated Report.
• The body of the report includes a discussion of the Idaho Statewide Wadeable Stream Survey (conducted from 2005 to 2008) and the Idaho Major Rivers Survey (conducted from 2006 to 2008). These surveys were conducted statewide using a probability-based approach and satisfy §305(b) reporting requirements of the Clean Water Act.

Summary of Water Quality Support Status in the 2010 Integrated Report

Based on existing and readily available water quality data and information assessed for the 2010 Integrated Report, 29% of streams and 4% of lakes are fully supporting state water quality standards, 36% of streams and 56% of lakes are not fully supporting state water quality standards, and 35% of streams and 40% of lakes have not been assessed.

Viewing Options

• Download the 2010 Integrated Report.
• View an overall map of all water bodies in the state (32" x 42").
• Use an interactive map to search for water body-specific results.