State of New Mexico > Environment Department > Surface Water Quality Bureau

Surface Water Quality Bureau
Monitoring, Assessment & Standards Section
Total Maximum Daily Loads
and TMDL Alternatives

Under Section 303(d)(1) of the federal Clean Water Act, each state is required to develop a list of waters within that state which are not in compliance with current water quality standards and establish a total maximum daily load (TMDL) ), or prepare an TMDL Alternative (i.e., IR Category 4b Demonstration), for each assessment unit-pollutant combination.

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Image: The Jemez River

                                 Kris Barrios
               Acting TMDL Coordinator
                         (505) 827-2621

A TMDL is defined as “a written plan and analysis established to ensure that a waterbody will attain and maintain water quality standard including consideration of existing pollutant loads and reasonably foreseeable increases in pollutant loads” (USEPA 1999). TMDLs have become an integral part of New Mexico’s Water Quality Management Plan.

Through the NM Water Quality Act, the State Legislature has empowered the Water Quality Control Commission with the authority to create such planning documents. The NMED is the agency responsible for implementing and enforcing the regulations adopted by the WQCC, including the development of TMDLs.

According to 40 Code of Federal Regulations (CFR) Part 130, TMDLs are the sum of the individual Waste Load Allocations (WLAs) for point sources and Load Allocations (LAs) for nonpoint sources (NPSs) and background conditions, and includes a margin of safety (MOS). A point source is a discrete discharge of pollution through a pipe or similar conveyance. A nonpoint source is any non-specific source of pollution (e.g. agricultural/rangeland runoff). Current estimates indicate that nonpoint sources are the cause of approximately 95% of the state’s water quality problem. The MOS accounts for uncertainty in the loading calculation. The MOS may not be the same for all waterbodies due to differences in the availability and strength of data used in the calculations. TMDLs are not regulatory documents, but they can be used to issue or modify permits for point sources. Non-point source pollution problems are addressed through non-regulatory programs including CWA §319(h) grants.

If there is adequate information provided to ensure that pollution control requirements other than TMDLs are stringent enough to achieve an applicable water quality standard, these assessment unit-pollutant combinations may be proposed for CWA 303d/305b Integrated Reporting (IR) Category 4b on the Integrated List.   An IR Category 4b Demonstration must be prepared following the guidelines available in Appendix H of the Assessment Protocols in order to explain the regulatory controls, currently in place and planned, that are stringent enough to attain applicable Water Quality Standards within a reasonable time period, thus providing an alternative to development of a TMDL.  IR Category 4b Demonstrations are also an important part of NM’s Water Quality Management Plan.

Bulleted item List of TMDLs and TMDL alternatives Bulleted item Forest Guardians v. C. Browner (1996)
Bulleted item MOU between NMED & USEPA (2001) Bulleted item Settlement Agreement (1997)
Bulleted item Steps for TMDL Development Bulleted item Consent Decree Dismissal (2009)
Bulleted item Prioritization Framework and Long Term Vision for Water Quality in New Mexico (2015) Bulleted item 4Q3 Low Flow Protocol for Ungaged Streams (USGS, 2002)
Bulleted Item Clean Water Act (CWA)    
Bulleted Item CWA §303 (d) - Impaired Waters and Total Maximum Daily Loads
Bulleted Item CWA §305 (b)- National Water Quality Inventory to Congress
Bulleted Item Monitoring and Assessing Water Quality
Bulleted Item WATERS (Watershed Assessment, Tracking, & Environmental ResultS)
Bulleted Item ATTAINS Database for Integrated 303(d)/305(b) Reporting
Bulleted Item Impaired Waters and TMDL Information
Bulleted Item EnviroMapper for Water
Bulleted Item Water Quality Standards Database

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