Estuary Monitoring Program

The first comprehensive estuarine water quality monitoring program supported by the TWDB was the Datasonde Program (also known as the Ambient Bay Water Quality Monitoring Program) which began in 1986.  Since that time, TWDB has supported the Datasonde Program and other monitoring efforts through general revenue and Research & Planning Funds.

The purpose of such monitoring is to support calibration and validation of estuarine hydrodynamic and salinity transport models and for development of freshwater inflow-salinity relationships to aid in water resources planning.  These needs are met by providing high-frequency data (most measurements every 15 to 60 minutes) which track changes in the pattern of salinity resulting from changing river flows or meteorological events.  Although monitoring is concentrated in the major estuaries, and even then the number of sites at which data are collected is small - two per estuary in most cases, the instruments provide an abundance of data for characterization of estuarine variability.  Bays of the Texas coast are dynamic, responding to perturbations of greater and lesser impact.  This monitoring program provides data from which short-term and long-term trends can be studied.

Data collection activities for the Datasonde Program are conducted by the Texas Parks and Wildlife Department (TPWD) as part of a partnership with TWDB to maintain a data collection and analytical study program focused on determining the effects of and needs for freshwater inflows to the state's bays and estuaries (following HB 2 (1985), SB 683 (1987), and SB 1 (1997)).

Hydrolab datasondes first were deployed in the fall of 1986 in Galveston, Trinity, Matagorda, Lavaca, San Antonio, Mesquite, Aransas, Corpus Christi, and Nueces bays.  Over the years, sites have been added or removed from the monitoring program depending on data needs.  Despite these changes, five sites have been monitored continuously for over 20 years and four others for 10 or more years.  Presently, 16 sites are monitored in nine bay systems, including: Sabine Lake (2), Trinity (2), Galveston (3), Cedar Lakes (2), Matagorda (1), Lavaca (1), San Antonio (1), Corpus Christi (1), Upper Laguna Madre (1), and Lower Laguna Madre (2)

Additional data representing other sites within the major, minor, and riverine estuaries is available upon request.  However, these data typically were collected as part of special studies and therefore have shorter periods of record.  Examples include monitoring in the Rio Grande Estuary, Brazos River and San Bernard Estuary, and Nueces Delta, as well as a number of estuary-specific freshwater inflow needs studies.

To download data, please go to the Coastal Data Page.