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Nutrient Criteria Development

Explanation of the process to develop nutrient criteria for inclusion in a future update to the Texas Surface Water Quality Standards.


Texas currently controls nutrient loadings to water bodies through its Surface Water Quality Standards, watershed rules, and antidegradation considerations in permitting actions using both narrative and numerical nutrient criteria. Until the 2016 Texas Integrated Report of Surface Water Quality, TCEQ assessed nutrients in surface waters based solely on narrative criteria.

TCEQ began developing numerical nutrient criteria to include in the Surface Water Quality Standards in 2000, establishing its first nutrient criteria development plan in 2001. TCEQ has updated that plan several times, most recently in 2014, in coordination with EPA, an advisory workgroup, and through other public meetings and forums.

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Status of Nutrient Criteria Development

TCEQ updated the Implementation Procedures to control nutrient discharges from proposed wastewater treatment facilities through permits in June 2010. Also in 2010, TCEQ adopted numerical nutrient criteria for 75 reservoirs in the 2010 Texas Surface Water Quality Standards. In July 2013, EPA approved the adopted criteria for 39 reservoirs and disapproved them for 36. The approved criteria were incorporated in Section 307.10 (Appendix F) of the 2018 Standards, the most recent version adopted by TCEQ. See EPA’s July 2, 2013 letter  and EPA’s Nutrient Criteria Technical Support document   for more information about EPA actions on Texas nutrient criteria.

TCEQ assesses standards attainment using the approved numeric criterion chlorophyll a in the 39 reservoirs that have approved numerical nutrient criteria. When assessing other water bodies, TCEQ screens instream concentrations of phosphorous, nitrate nitrogen, and chlorophyll a to indicate areas of possible concern for nutrient enrichment as reported in the biennial Texas Integrated Report of Surface Water Quality.

TCEQ is currently conducting and evaluating additional studies to develop numerical nutrient criteria for freshwater streams and rivers, estuaries, and tidal streams, as well as for reservoirs without approved numerical nutrient criteria. TCEQ’s next proposal of numerical criteria for the Standards will be developed with extensive public participation to be both scientifically defensible and cost-effective.

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Nutrient Criteria Development Plan

TCEQ first established a Nutrient Criteria Development plan in 2001, which was revised in 2004 and 2006. On August 20, 2014, TCEQ sent the latest revised and expanded version of the Adobe Acrobat PDF Document Nutrient Criteria Development Work Plan for the State of Texas to EPA. The 2014 plan reflects comments received during a public comment period that ended June 22, 2012.

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Public Participation

The Nutrient Criteria Development Advisory Work Group advises TCEQ on the development of nutrient criteria—including strategies, categorization of water bodies, and additional data needs. Membership and meetings of the work group are open to anyone interested in joining.

For more information about the work group, please e-mail, fax to Standards at 512/239-4410, or send a letter to TCEQ, MC-234, PO Box 13087, Austin, Texas 78711-3087.

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