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NYS Section 303(d) List of Impaired/TMDL Waters

The New York State Section 303(d) List of Impaired/TMDL Waters identifies those waters that do not support appropriate uses and that may require development of a Total Maximum Daily Load (TMDL). The Section 303(d) List is updated every two years. The current List in effect is the Final 2016 NYS Section 303(d) List (PDF, 167 KB) (July 2017).

The 2016 NYS Section 303(d) List

The Proposed Final NYS 2016 Section 303(d) List was "partially approved and partially disapproved" by USEPA on July 21, 2017. In its letter of partial approval/partial disapproval (PDF, 107 KB), USEPA stated that it approved New York State's listing of 792 waterbody/pollutant combinations requiring TMDLs that New York has included on its list. However, USEPA stated that is was disapproving the State's decision not to list 71 waterbody/pollutant combinations.

Prior to the USEPA partial approval/partial disapproval, a Draft 2016 Section 303(d) List was made available for public comment for a 45-day period that ended March 4, 2016. After considering comments received from the public, a Proposed Final List was submitted to USEPA on December 21, 2016.

Comments received during the public notice of the Draft List and other issues raised by USEPA during their review of the Draft List are addressed in a Response Summary (PDF, 331 KB).


The Federal Clean Water Act requires states to periodically assess and report on the quality of waters in their state. Section 303(d) of the Act also requires states to identify impaired waters, where designated uses are not fully supported. For these impaired waters/pollutants, states must consider the development of a Total Maximum Daily Load (TMDL) or other strategy to reduce the input of the specific pollutant(s) restricting waterbody uses, in order to restore and protect such uses.

The waterbody/pollutant listings in the Section 303(d) List are segmented into a number of categories. The various categories, or Parts, of the list include:

  • Part 1 - Individual Waterbodies with Impairment Requiring a TMDL,
  • Part 2 - Multiple Segment/Categorical Impaired Waterbodies - Includes Acid Rain Waters, Fish Consumption Waters, and Shellfishing Waters,
  • Part 3 - Waterbodies for which TMDL Development May Be Deferred - Includes Waters Requiring Verification of Impairment, Waters Requiring Verification of Cause/Pollutant, and Waters Where the Development, Implementation and/or Evaluation of Other Restoration Measures is Pending.

Impaired Waters NOT Included on the NYS Section 303(d) List

Not all impaired waters of the state are included on the Section 303(d) List. By definition, the List is limited to impaired waters that require development of a Total Maximum Daily Load (TMDL). A list of Other Impaired Waterbody Segments Not Listed (PDF, 83 KB) on the 303(d) List Because Development of a TMDL is Not Necessary is also available. The purpose of this supplemental list is to provide a more comprehensive inventory of waters that do not fully support designated uses and that are considered to be impaired. (NOTE: This list will be updated upon USEPA approval of the Proposed Final 2016 List.)

There are three (3) categories of justification for not including an impaired waterbody on the Section 303(d) List:

  • Category 4a Waters - TMDL development is not necessary because a TMDL has already been established for the segment/pollutant.
  • Category 4b Waters - A TMDL is not necessary because other required control measures are expected to result in restoration in a reasonable period of time.
  • Category 4c Waters - A TMDL is not appropriate because the impairment is the result of pollution, rather than a pollutant that can be allocated through a TMDL.

2016 Waterbody/Pollutant Delistings

A separate list of waterbody/pollutant combinations that were included on the previous (2014) Section 303(d) List, but that are NOT included on the 2016 List is also available. This list of 2016 Water/Pollutant Delistings (PDF, 32 KB) provides some linkage and continuity between the previous and current Lists. The specific reason why a waterbody/pollutant was removed from the List (i.e., delisting action, reassessment, re-segmentation, etc.) is included in this document. Some of these waterbodies/pollutants (specifically, those that have been delisted but that remain impaired) also appear on the list of Other Impaired Waterbody Segments Not Listed Because Development of a TMDL is Not Necessary.

All Impaired Waters

A searchable, sortable spreadsheet of all impaired waters/pollutants is also available. The All Impaired Waters List (Excel, 76 KB) includes both Section 303(d) List waters, as well as Category 4a, 4b and 4c waters that are impaired but not included on the Section 303(d) List.

Consolidated Assessment and Listing Methodology

An outline of the process used to monitor and assess the quality of New York State waters is contained in the New York State Consolidated Assessment and Listing Methodology (CALM). The CALM describes the water quality monitoring, assessment and listing process in order to improve the consistency of assessment and listing decisions. Two components of the CALM, the Assessment Methodology (PDF, 301 KB) and Listing Methodology (PDF, 134 KB), were both used in compiling the Final 2016 Section 303(d) List. The third of the 3 parts of the CALM is a Monitoring Strategy (PDF, 803 KB) which provides an overview of the NYSDEC statewide water quality monitoring program.

Additional information regarding the NYSDEC Water Quality Assessment Program, including the Waterbody Inventory/Priority Waterbodies List assessments and Section 305(b) water quality reporting can also be found on the NYSDEC website.

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