Study Results: Development of Use-Based Chlorophyll Criteria for Recreational Uses of Reservoirs

In 2002, EPA mandated that states develop numeric nutrient water quality standards for lakes, streams, and estuaries. TCEQ’s plan for developing nutrient standards specifies that major reservoirs will be the first water bodies for which nutrient standards will be considered.

The TWCA, in collaboration with other entities, initiated a study intended to provide data that the TCEQ can use to determine criteria that are supportive of recreational uses and then evaluated in conjunction with criteria supportive of other uses to determine a recommended water quality standard.

This study recommends that the nutrient water quality standards for reservoirs be based on chlorophyll-a, since the density of planktonic algae is most frequently the nutrient-related condition affecting the desirability of reservoirs for recreational uses.

Support for the study came from the National Association of Clean Water Agencies and Texas Association of Metropolitan Sewerage Agencies. Participants included the Brazos River Authority, Guadalupe-Blanco River Authority, Lower Colorado River Authority, Sabine River Authority, San Antonio River Authority, Tarrant Regional Water District, and Trinity River Authority (TRA). Consultants assisting in the effort were Alan Plummer Associates, Inc., and William W. Walker, Jr., Ph.D.

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