Released in July 2000 Go to Original Version

A:    Briefly, TMDL stands for "Total Maximum Daily Load". A TMDL can be best described as a waterbody, watershed or basin-wide budget for pollutant influx to a watercourse.

Q:    The first edition of Questions and Answers about TMDLs indicated there is a 20-year schedule for the development of TMDLs in New Mexico.  How was that schedule established?

A:    The schedule was established as part of the negotiated consent decree resolving a lawsuit entitled Forest Guardians and Southwest Environmental Center v. Carol Browner [U.S. Environmental Protection Agency](CIV. NO. 96-0826 LH).  The schedule outlined in the consent decree is based, largely but not wholly, on the State's 1996-1998 Clean Water Act §303(d) List of waters needing TMDLs in New Mexico.

Q:    What is a §303(d) list?

A:    Briefly, §303(d) of the federal Clean Water Act requires each state to identify surface waters within its boundaries that are not meeting, or expected to meet, water quality standards. Section 303 further requires the states to prioritize their listed waters for development of TMDLs.  If the states do not adopt TMDLs to address the problem, The U.S. Environmental Protection Agency must prepare TMDLs on their behalf.

Q:    Has New Mexico’s §303(d) list changed since the 1996-1998 version?

A:    Yes, federal regulations [40 CFR 130.7(d)] require the list be reviewed and submitted to USEPA for approval every two years.  The 1998-2000 version of the §303(d) list has been adopted by the NM Water Quality Control Commission and approved by the USEPA.  The current 2000-2002 version is now available, also.

Q:    Procedurally how was the §303(d) list changed, and was there public involvement?

A:    The Surface Water Quality Bureau of the Environment Department has been delegated  the task of preparing §303(d) listings by the New Mexico Water Quality Control Commission.  In preparing the 1998 version, the Bureau undertook a comprehensive review of all new and existing water quality data for surface waters in New Mexico.  This review involved definition and refinement of Bureau protocols for the use and analysis of data to ensure a standard and defensible approach to the evaluation.  These data assessment protocols underwent careful and complete review by numerous public agencies, such as USEPA, NM Department of Game and Fish, US Fish and Wildlife Service, etc.  After preparing the first draft of the §303(d) list, the Bureau accepted public comments from March 10, 1998 to April 10, 1998 (See the USEPA approval letter and the 1998 Record Of Decision).  The current §303(d) listing's approval letter and the draft Record of Decision are now available, also.

Q:    The schedule indicates TMDLs for the Lower Pecos River and the Lower Rio Grande were due for completion by December 31, 1997, and December 31, 1998 respectively, what happened and why?

A:    A three-season intensive survey was done on the lower Pecos River From Sumner Dam to Brantley Resevoir in 1997.  The data collected showed no exceedences of the applicable surface water quality standards.  It was determined that a TMDL was not necessary at this time.  A data review by Tetra Tech, an EPA contractor, showed that the lower Rio Grande is currently meeting all applicable surface water quality standards and that a TMDL was not necessary at this time.  The decision not to develop TMDLs in these two instances was supported by the WQCC.

Q:    Even though TMDLs were not necessary for the Lower Pecos, and the Lower Rio Grande, obviously TMDLs will need to be developed elsewhere in the state.  How is NMED involving the community and other stakeholders?

A:    NMED holds pre-monitoring meetings (general public and stakeholders) in the watersheds to be studied in a given year.  After the data is collected, analyzed and QA’d (quality assurance has been done), parameters which exceed applicable surface water quality standards are listed on the §303(d) list.  If a TMDL is scheduled to be written for a specific waterbody in the watershed which was studied, one is drafted, opened for public comment at which time another meeting is held with the stakeholders in the watershed to solicit their comments.  Comments are also accepted at the regularly scheduled WQCC meeting where the draft TMDL is being offered for formal approval to the Commission.

Q:    Is the State restricted to adopting TMDLs on streams listed in the Consent Decree?

A:    No.  Certain watersheds and or waterbodies can be moved forward due to a need to accommodate other interests in the process.  The Bureau discourages this approach but does make acceptions when necessary.

Q:    Did the Bureau write any TMDLs in 1999?

A:    Yes.  The Domestic Water Supply Bundle was due by December 31, 1999 (consent decree schedule). Forty-seven (47) individual parameters on eleven (11) stream reaches were listed from the 1996 §303(d) list.  Twenty-one (21) TMDLs were written for consent decree-listed parameters.  Twenty-six (26) TMDLs were not necessary for consent decree listed parameters due to the collection of current water quality data.  Five (5) additional TMDLs were written outside of the consent decree listed parameters.  A total of twenty-six (26) TMDLs were written in 1999.

Q:    Are TMDLs implemented?

A:    For point sources, implementation consists of issuing National Pollutant Discharge Elimination System (NPDES) permits which will reflect the limits set forth in the TMDL for those pollutants of concern which can be regulates under NPDES.  For nonpoint sources, the Bureau relies on the voluntary approach to pollution abatement.  The federal CWA does not regulate nonpoint sources, rather it relies on states and other entities to come up with innovative best management practices (BMPs) to abate pollutant loads.  The Bureau’s Watershed Protection Program makes federal grant monies available through a yearly request for proposal (RFP) process which allows public and private entities to submit proposals to abate pollutant loads in their watersheds.  These RFPs follow the development and approval of TMDLs in the priority watersheds.

Q: What is the TMDL schedule for the next 10 years?

A:    The following timeline depicts anticipated TMDL development in New Mexico:

Q: Where can I get more information about TMDLs in New Mexico?

You can also reach us directly by telephone weekdays 8-5pm MST at (505) 827-2981 or by fax at (505) 827-0160.  We're on the internet at: http://www.nmenv.state.nm.us.  National information is available online by accessing the USEPA’s TMDL webpage at www.epa.gov/owow/tmdl.