1. Role of the Texas Water Development Board in Environmental Flow studies Barney Austin Surface Water Resources Division Texas Water Development Board May 21, 2004

2. TWDB Offices Office of Finance Office of Project Finance & Construction Resource Information Office Office of Planning (Bill Mullican) Water Resource Planning Conservation Groundwater Resources Surface Water Resources  Instream Flows  Bays and estuaries

3. Role of TWDB in Bays & Estuaries studies Funding Research & Planning Fund: $417,046 per year for Environmental studies (data, model enhancement, research and reviews) Data collection: Partly collected by TWDB staff, also through grants (e.g. TCOON Tide gages, USGS streamgages)

4. Role of TWDB in Bays & Estuaries studies Hydrology & data collection Estimating the total surface water inflow to our bays and estuaries  Rainfall, evaporation, gaged flow, ungaged flow  Watershed delineation  TxRR: Rainfall-Runoff model Salinity and tide data compilation, analysis.

5. Role of TWDB in Bays & Estuaries studies Optimization TxEMP (Texas Estuarine Mathematical Programming model) Inflow-Harvest (or catch) statistical regression equations for individual species Development of total Harvest vs. Inflow curve for the bay, including appropriate constraints Objective framework for balancing competing demands

6. Role of TWDB in Bays & Estuaries studies Nutrient balance Study and quantification of level of nutrients required to maintain the health of the bay Provides further validation of the optimization results

7. Role of TWDB in Bays & Estuaries studies Hydrodynamic modeling TxBLEND 2-D, finite element model for determining distribution and concentration of salt across the bay Calibrated using long-term salinity measurements and intensive survey data Used for TPWD verification of needs analysis and nutrient balance work TxBLEND used for other applications…

8. Role of TWDB in Instream Flow studies Funding Research & Planning Fund (share $417,046 per year for environmental studies  Reconnaissance and data gathering contracts with: San Antonio River Authority Lower Sabine River Authority Brazos River Authority Administered by the TPWD  Principally for biological data collection

9. Role of TWDB in Instream Flow studies

10. Summary More technical detail in later presentations Stakeholder participation and contribution crucial to complete legislative mandates Funding Acceptance of results Look forward to receiving guidance from the legislative committees