The Texas Instream Flow Program Barney Austin Surface Water Resources Division Texas Water Development Board May 21, 2004

Senate Bill 2 The Texas Legislature directed tri-agencies (TPWD, TWDB, and TCEQ) to: Establish and continuously maintain an instream flow data collection and evaluation program, and Develop methodologies to determine flow conditions in Texas rivers and streams necessary to support a sound ecological environment.

Senate Bill 2 Framework for Instream Flow Study Program requires tri-agencies to: Share oversight of program studies. Share data, studies, analysis, information and reports. Establish a Work Plan that prioritizes studies and sets interim deadlines for publication of flow determinations, and Complete priority studies by December 31, 2010.

Senate Bill 2 Framework for Instream Flow Study also: Requires TCEQ to consider the results of completed studies in its review of any management plans, water rights, or interbasin transfers.

Joint study accomplishments: Interagency MOA (Executed: Oct 17, 2002) Programmatic Work Plan (Final: Dec 19, 2002) NAS contract (July 2003) Technical Overview (Draft: August 8, 2003)

Summary of Agency Roles Instream Flow Study Element Coordinating Agency Study DesignJoint Hydrological and Hydraulic EvaluationTWDB Biological EvaluationTPWD Physical Processes EvaluationJoint Water Quality EvaluationTCEQ IntegrationJoint InterpretationJoint Study ReportJoint Monitoring and ValidationJoint

Texas Instream Flow Studies

Timeframes for Priority Studies Subbasin Lower Guadalupe River Lower Brazos River Lower San Antonio River Middle Trinity River Lower Sabine River Middle Brazos River Sabine R. Toledo Bend

Second Tier of Studies Upper Guadalupe River Neches River Red River Upper Sabine River Two special studies include the Sulphur River (on-going) and the Lower Colorado River (monitoring). Developed to provide future direction in studies in the event priorities change or supplementary resources are made available. These include: Sulphur R. Colorado R.

Tiered Aquatic Life D.O. Toxic Criteria Aquatic Life Human Health Bacteria ---- Contact Recreation Chloride, Sulfate, Total Dissolved Solids pH as absolute minima and maxima Temperature as absolute maxima TCEQ – Water Quality & Specific Numeric Criteria

Sound Ecological Environment Maintain Ecological Integrity processes & functions that create & maintain habitat & other physicochemical conditions that support survival, growth, & reproduction Conserve Biodiversity fish, invertebrates, mussels, plants … riparian diversity

Biological approach Coordinating Agency - Texas Parks & Wildlife Field surveys to develop sampling strategies and characterize biota and habitat 3 contracts to be executed for reconnaissance on priority sub-basins. Habitat-based approach Geomorphology, hydrology and hydraulics Two complementary analyses using spatially-explicit habitat models  Microhabitat availability using habitat guilds and/or target species  Habitat heterogeneity (diversity/complexity) using landscape metrics Develop habitat-discharge functions and time-series Important to consider:  Both channel and riparian areas…also consider watershed; connectivity  Key habitats; environmental requirements and life history of flow dependent biota  Temporal considerations

Hydrology & Hydraulics TCEQ - Water Availability Model (WAM)

Hydraulic Modeling – Brazos River DOQQ photo taken February 4, 1995; ~7,500 cfs Boundary of FE Mesh used for flows below 3350 cfs is shown in green. Detail Area

Hydraulic Modeling – Brazos River Finite Element Mesh (approximate element resolution 8m x 10m) RMA-2 (depth averaged, hydrostatic Reynolds Averaged Navier-Stokes equations) 1456 cfs shown FE mesh with depth contours 0.0m to 4.0m FE mesh with velocity contours 0.0 to 2.25 mps

Hydraulic Modeling – Brazos River Photo of “Island” area, November 2, Flow is approximately 1500 cfs.

Fish habitat utilization studies

Habitat Modeling– Brazos River Mesohabitats are delineated for 1456cfs using a grid-based GIS model

Mesohabitat vs. discharge

INSTREAM FLOW STUDY: Brazos River near Allens Creek Reservoir Velocity Contour Plot

Modeling Issues – Large woody debris Large Woody Debris (LWD) influences both hydraulics and habitat utilization analysis North Sulphur (near confluence) South Sulphur near Cooper Sulphur US of Patman (near Site 2)

Modeling Issues – Mesh Interpolation MEBAA bounding boxes Typical radial bounding regions Interpolating bathymetric single-beam data to the finite element mesh Exploit the anisotropic shape of the river cross- section for a better interpolation Use flow-directional coordinate system (either linear {TWDB} or curvilinear {CRWR})

Modeling Issues – Mesh Interpolation Standard IDW interpolation using Surface Water Modeling System Improved IDW interpolation using Mesh Elevating and Bathymetry Adjusting Algorithms (MEBAA)

Modeling Issues - Geomorphology Bathymetry that changes with flow Surveying (High Flow) Modeling (Low Flow) Affects both hydraulic and habitat analysis

Physical Processes Flushing flows (> once per year) Restore/enhance riffle habitat Remove surficial and interstitial fine sediment Determined through study of sediment and hydraulic model output Channel maintenance (circa 1.5 per year) Maintain physical characteristics of the channel Study of flow-duration curves Floodplain maintenance (once per 1-10 years) Build and bring nutrients to the floodplain Extent and frequency from (existing?) 1-D models or aerial photos Valley maintenance Q25-ish

Integration and Interpretation

National Academy of Sciences 1. $300k contract executed in July Evaluate science and methodology in key documents 3. Review and provide advice on scientific and technical matters relevant to the Instream Flow Program 4. Evaluate findings and recommendations of Tasks 1 and 2 for consistency with the requirements of Texas law for the study of Instream Flows Final Report due Oct 2004 Dr. Lauren Alexander (NAS) testified at the Feb 18 th Study Commission meeting

National Academy of Sciences Have had three open meetings in Texas Austin, San Antonio, San Marcos Questions/answers and public testimony “Panel of experts” for second meeting Not able/willing to release draft report Comprehensive guide to be used by any entity conducting instream flow studies in Texas…and beyond?

Instream Flow Study Program Results Will Be: An essential database for conservation of fish and wildlife resources in Texas. Used in the State’s water rights permitting process, and Incorporated into future regional and state water plans.

For more information…. Barney Austin Texas Water Development Board Tel: