Texas Bay and Estuary Study Program Cindy Loeffler Flows for the Future October 31, 2005

Freshwater Inflows… Salinity Nutrients Sediments …By Definition Create and Sustain Estuaries

TWC Section Defines Beneficial Inflows As the “Salinity, Nutrient, and Sediment Loading Regime Adequate to Maintain an Ecologically Sound Environment in the Receiving Bay and Estuary System That Is Necessary for the Maintenance and Productivity of Economically Important and Ecologically Characteristic Sport or Commercial Fish and Shellfish Species and Estuarine Life Upon Which Such Fish and Shellfish Are Dependent.” The Fundamental Scientific Basis of the Studies The Fundamental Goal of the Recommendations

The Process of Developing FWI Recommendations FWI Recommendations Optimization Model TxEMP Hydrodynamic & Conservation Transport Model TxBLEND Hydrographic Survey Nutrient Analysis Sediment Analysis Fisheries Regression Analysis Objectives & Constraints Fisheries Needs Analysis Habitat Analysis Hydrology Verification

FWI Recommendations Are Based on the Biological Needs of a Group of Target Species Expressed As A Statistical Relationship Between Harvest or Catch per Unit Effort And Inflow H = – 145.3*ln(Q jf ) *ln(Q ja ) – 141.4*ln(Q so ) H = *ln(Q ma ) – 963.3*ln(Q mj ) + 710*ln(Q ja ) *ln(Q so ) H = *Q mj *Q ja – *Q nd H = *Q jf – *Q ma *Q nd ln(H) = – *ln(Q ma ) *ln(Q mj ) – 1.086*ln(Q nd ) ln(H) = – *ln(Q ma ) *ln(Q mj ) – 1.086*ln(Q nd ) ln(H) = *ln(Q ja ) – *ln(Q so ) H = *ln(Q jf ) *ln(Q mj ) – 155.1*ln(Q ja ) *ln(Q nd ) Blue Crab Eastern Oyster Red Drum Black Drum Spotted Sea- Trout Brown Shrimp White Shrimp Target Species:

TPWD and TWDB Have Jointly Developed FWI Recommendations To Maintain the Health and Productivity of Texas Estuaries TxEMP Is The Optimization Model That Produces a Range Of Inflows Within Which Estuarine Health and Productivity Needs May be Met

MinQ Is the Minimum Inflow That Maintains 80% Of Mean Historic Harvest and All Other Physical Constraints: Salinity, Nutrient, and Sediment Needs MaxH is FWI Necessary To Sustain Historic Fisheries Harvest as Evaluated Against Existing Fisheries Data To Meet The Legislative Definition Of Beneficial Inflows A Range Of Possible Solutions Lies Between Two Points Along An Optimization Curve: MaxQ and MinQ

FWI Seasonal Distribution San Antonio Bay The Recommended FWI Is Often Expressed As a Single Annualized Number, But Always Infers The Sum of Bi-Monthly Inflows Delivery of Freshwater Inflows Must Incorporate Seasonality to Have Any Ecological Significance

FWI Recommendations Summary: Methodology to Determine the Freshwater Inflows Necessary to Meet the Legislative Directive of TWC Section Create Models That Integrate Datasets and Predict Response To Varying Freshwater Inflows Identify and Assemble Datasets Representative of Estuarine Ecosystem Identify and Assemble Datasets That Reflect Changes in Inflows Input Real Data Into Models And Assess Projected Estuarine Conditions

Sabine 9.5* Galveston 5.2 Matagorda 2.0 San Antonio 1.15 Aransas 0.82 Nueces 0.14 Laguna Madre 0.25 * Millions of Acre Feet Per Year Legislatively Mandated Studies to Determine “Beneficial Inflows” Necessary to Conserve Health and Productivity Of Texas Major Estuaries Have Been Completed. Some are Being Updated.

Galveston Bay Case Study

TxEMP MinQ and MaxH Solutions

TxEMP Monthly Flow Distribution

TXBLEND Output Monthly Salinity Maps Under Each TxEMP Solution Monthly Salinity Maps Under Each TxEMP Solution Salinity Difference Maps Salinity Difference Maps Spatial Relationships of Modeled Salinity Zones to Critical Habitat Areas Spatial Relationships of Modeled Salinity Zones to Critical Habitat Areas

White Shrimp Abundance in Galveston Bay Higher abundance correlates with lower salinity levels Higher abundance correlates with lower salinity levels

Galveston Bay TXBLEND Time Series Daily salinity at a point in Upper Galveston BayDaily salinity at a point in Upper Galveston Bay Predicted salinity within upper and lower limits for MaxH and MinQPredicted salinity within upper and lower limits for MaxH and MinQ

TxEMP MinQ and MaxH Solutions TPWD Recommendation

Comparison of Model Solutions to Historical Inflows

“Nowhere in the World Has the Issue of Freshwater Inflow Been Studied So Systematically, or The Results Used to Guide Water Management Policies and Practices So Effectively, Than in the State of Texas.” – A Review and Application of Literature Concerning Freshwater Flow Management in Riverine Estuaries (2000), by Dr. E. Estevez, Director, Center for Coastal and Tropical Ecology, Mote Marine Laboratory, Sarasota, Florida. Methods for Determining Minimum Freshwater Inflow Needs of Texas Bays and Estuaries - Powell, Matsmuto, Brock. In Estuaries December Reviews

“While the State of Texas has pioneered tools to address freshwater inflow needs for bays and estuaries, there are limitations to these tools in light of both scientific and public policy evolution.” – Science Advisory Committee to the Study Commission on Water for Environmental Flows, Interim Report to the 79 th Legislature, December 2004 Reviews

Summary of SAC B&E comments Incorporate stakeholder input/peer review Commercial vs. independent fisheries data Improve statistical methods TPWD “Verification” analysis Optimum inflow vs. drought conditions Adaptive management and precautionary principle methods