Flow Studies

Testing agencies need flow data to evaluate and accurately apply certain State water quality standards. Unfortunately, five to six years ago, no Clean Rivers Program partners were collecting flow data for submission to TCEQ. Local partners sampled numerous locations during each day's sampling run, and time became critical in getting samples to the lab. To maintain their schedules without major modifications, H-GAC developed a flow monitoring method to allow one person to quickly and efficiently collect the required information, and the USGS developed a "ratings curve" method to estimate flow and to be applied to several sites in the H-GAC region.

In 2004, the USGS identified five sites for which to complete "ratings curves", and data collection continued through 2006. Between 2006 and 2008, USGS completed "rating curves" for five locations within the Bastrop Bayou watershed. In 2008, H-GAC's Clean Rivers Program purchased wadeable flow meters and two partners began collecting flow data on an intermittent basis. In late 2009, H-GAC's Clean Rivers Program purchased hydroboard mounted flow meters for three local partners to collect flow data from non-wadeable streams. Today, two local partners collect flow data at every non-tidal site consistently while personnel issues limit one partner to collecting quarterly flow data from selected locations only. Where ambient monitoring sites can be matched, USGS gage data is included with data submissions to TCEQ. With the purchase of the new flow measuring equipment, the Bastrop Bayou ratings curves have become unnecessary. Because the ratings curves have to be periodically updated, H-GAC needs to evaluate whether updating the "curves" is the best use of resources.

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