Skip to Main Content

DEQ Title, click to go to DEQ home page

WQD Home Page
List of all WQD programs
Rules & Regulations
General Permits
Publications and Other Documents
A list of useful contacts in WQD
General Information about WQD
Water Quality Division > Programs > Integrated Water Quality Assessment [305(b)/303(d)]

Integrated Water Quality Assessment [305(b)/303(d)]

2016 303(d) List Approved

27 April 2018 - USEPA Region 6 has approved Oklahoma's 2016 303(d) list of impaired waters. The approval letter and decision document describe the approval process in detail. The 2016 303(d) list of Category 5 (impaired) waterbodies is found in Appendix C of the 2016 Integrated Report ("Water Quality in Oklahoma - 2016"). The 2016 303(d) list is considered the state's official list of impaired waters until the 2018 303(d) list is approved by USEPA Region 6.

An interactive map of Oklahoma’s waterbodies is available at

2016 Water Quality Assessment Summary

During the 2015-2016 reporting cycle, there were a total of 4,212 waterbodies delineated into the Oklahoma Assessment Database (ADB). These waters include approximately 33,016 river and stream miles and 621,051 lake acres.

Each beneficial use of an assessed waterbody is evaluated based on real data according to the State's well-formed, science-based assessment methodology. This methodology categorizes waters into one of five categories. A summary of the assessment results are shown here.

2016 Water Quality Assessment Summary Table


Cat 1

Cat 2

Cat 3

Cat 4

Cat 5













(# waterbodies)






Clean Water Act (CWA) Section 303(d) Requirements

The 1972 amendments to the Clean Water Act include Section 303(d). The regulations implementing Section 303(d) require states to develop lists of water bodies that do not meet water quality standards and to submit updated lists to the U. S. Environmental Protection Agency (EPA) every two years. Water quality standards, as defined in the Code of Federal Regulations, include beneficial uses, water quality objectives (narrative and numerical) and antidegradation requirements. The EPA is required to review impaired water body lists submitted by each state and approve or disapprove all or part of the list.

For water bodies on the 303(d) list, the Clean Water Act requires that a pollutant load reduction plan or Total Maximum Daily Load (TMDL) be developed to correct each impairment. TMDLs must document the nature of the water quality impairment, determine the maximum amount of a pollutant which can be discharged and still meet standards, and identify allowable loads from the contributing sources. The elements of a TMDL include a problem statement, description of the desired future condition (numeric target), pollutant source analysis, load allocations, description of how allocations relate to meeting targets, and margin of safety.

CWA Section 305(b) Requirements

The 1972 amendments to the Clean Water Act also include Section 305(b). The regulations implementing Section 305(b) require states to develop an inventory of the water quality of all water bodies in the state and to submit an updated report to the EPA every two years. This process was established as a means for the EPA and the U. S. Congress to determine the status of the nation's waters.

The 305(b) Report also includes: an analysis of the extent to which water bodies comply with the “fishable/swimmable” goal of the CWA; an analysis of the extent to which the elimination of the discharge of pollutants and a level of water quality achieving the “fishable/swimmable” goal have been or will be attained, with recommendations of additional actions necessary to achieve this goal; an estimate of a) the environmental impact, b) the economic and social costs, c) the economic and social benefits, and d) the estimated date of such achievement; and finally, a description of the nature and extent of nonpoint sources of pollutants, and recommendations of programs needed to control them — including an estimate of the costs of implementing such programs.

Integrated List Guidance

The US Environmental Protection Agency (USEPA) issued guidance for the development of an Integrated Water Quality Monitoring and Assessment Report (Integrated Report) by the States. This guidance recommends that States integrate their Water Quality Inventory Report (Section 305(b) of the CWA) and their Impaired Waterbodies List (Section 303(d) of the CWA). The Integrated Report is intended to provide an effective tool for maintaining high quality waters and improving the
quality of waters that do not attain water quality standards. The Integrated Report will also provide water resources managers and citizens with detailed information regarding the following:

  • Delineation of water quality assessment units providing geographic display of assessment results;
  • Progress toward achieving comprehensive assessment of all waters;
  • Water quality standards attainment status;
  • Methods used to assess water quality standards attainment status;
  • Additional monitoring needs and schedules;
  • Pollutants and watersheds requiring Total Maximum Daily Loads (TMDLs);
  • Pollutants and watersheds requiring alternative pollution control measures;
  • Management strategies (including TMDLs) under development to attain water quality standards; and
  • TMDL development schedules.

The Integrated Report will streamline water quality reporting since data sources and assessment methods will be described in detail, providing a sound technical basis for assessment decisions. Assessment results will also be conveyed in a spatial context, allowing a clearer picture of water quality status and issues. Monitoring needs and schedules will be described, facilitating the articulation of monitoring priorities and identifying opportunities for cooperation with other agencies and watershed partners. TMDL needs and schedules will be defined to convey plans for water quality improvements. The public participation aspects will provide opportunities for data submittal and open discussion of water quality assessment methods and results.

The Integrated Report combines the non-regulatory requirements of the Water Quality Inventory Report (305b) with regulation driven List of Impaired Waterbodies (303d) (i.e., only the latter mandates TMDL development). Successful integration into a single report requires a careful meshing of requirements and procedures. In general, Category 5 of the Integrated Report satisfies USEPA reporting requirements under Section 303d (Impaired Waterbodies) and, combined with the remaining Categories, document assessment under Section 305b (Water Quality Inventory). Therefore, the regulatory requirements (i.e., EPA approval and adoption; public participation, etc.) for 303d impaired waterbodies listing only apply to Category 5 of the Integrated Report.

The methods used to develop the Integrated Report are described in the Continuing Planning Process (CPP). One goal of the CPP is to provide an objective and scientifically sound waterbody assessment listing methodology including:

  • A description of the data that the State will use to assess attainment of surface water quality standards;
  • The quality assurance aspects of the data;
  • A detailed description of the methods used to evaluate water quality standards attainment;
  • The placement of waterbodies in one of 5 Categories:
    • Category 1 - Attaining the water quality standard and no use is threatened.
    • Category 2 - Attaining some of the designated uses; no use is threatened; and insufficient or no data and information is available to determine if the remaining uses are attained or threatened.
    • Category 3 - Insufficient or no data and information to determine if any designated use is attained.
    • Category 4 - Impaired or threatened for one or more designated uses but does not require the development of a TMDL.
      • 4a - TMDL has been completed.
      • 4b - Other pollution control requirements are reasonably expected to result in the attainment of the water quality standard in the near future.
      • 4c - Impairment is not caused by a pollutant.
    • Category 5 - The water quality standard is not attained. The waterbody is impaired or threatened for one or more designated uses by a pollutant(s), and requires a TMDL. This category constitutes the Section 303(d) list of waters impaired or threatened by a pollutant(s) for which one or more TMDL(s) are needed.
      • 5a - TMDL is underway or will be scheduled.
      • 5b - A review of the water quality standards will be conducted before a TMDL is scheduled.
      • 5c - Additional data and information will be collected before a TMDL or review of the water quality standards is scheduled.

    The CPP is a companion to the Integrated Report. It is anticipated that this will be a living document and will be modified, as appropriate, to accompany subsequent Integrated Reports.

For questions about the Integrated Water Quality Assessment Report, please contact Nicole Newcomer.

What's New

2016 Integrated Report
27 April 2018


2014 Integrated Report
18 May 2015

2012 Continuing Planning Process (CPP)

Public Notice | Final CPP | Response to Comments
10 Dec 2012

Archive of Previous Integrated Reports and CPPs