Texas Surface Water & Environmental Flows

Environmental Flows

As in most regions of the world, Texas is confronted with serious issues related to water supplies in support of economic life, human health and welfare, and environmental health.  Aquatic Ecology Lab conducted studies to contribute to the challenge of estimating environmental flow needs for the state’s streams, rivers and estuaries.  Dr. Winemiller has assisted the state with recent programs to evaluate technical approaches and to assess environmental flows.  Links to related websites and documents appear below.

River flow

Potential Influence of Exchanges between the Lower Guadalupe River and Oxbow Lakes on Food Web Dynamics

 Winemiller Aquatic Ecology Lab in collaboration with the River Studies Unit, Texas Parks and Wildlife Department

guadalupe-riverThe objective of this project is to contribute to Texas Instream Flow Program efforts on the lower Guadalupe River by examining how lateral connectivity may facilitate exchanges of organic material, including aquatic organisms, between the river channel and oxbow lakes to influence food web dynamics.  One of the most important functions of high-flow pulses in lowland rivers is creation of lateral connectivity between the river channel and aquatic habitats in floodplains.  Periodic high-flow pulses result in temporary connections between the river channel and oxbow lakes that provide important habitat for several fish species that normally are uncommon within the active river channel.  In the Texas coastal plains, oxbow lakes are highly productive aquatic habitats that function as nursery areas for many fish species, including some that are common within river channels.  Fishes, such as gars (Lepisosteus species) and shads (Dorosoma species), move between the river and oxbow lakes to exploit food resources.

cuero-oxbowFish movement between river channels and floodplain aquatic habitats during periods of lateral connectivity influences food web dynamics in both habitats.  Food-web dynamics affect, and are influence by, recruitment dynamics of aquatic organisms that in turn are influenced by ecosystem productivity in relation to flow conditions.  In the lower Guadalupe River, there are moderate increases in turbidity during high flow pulses, and the river channel remains net autotrophic.  According to a previous study, biomass of several common fish species within the lower Guadalupe channel has greater reliance on terrestrial sources of production during high flow pulses.   What remains unknown is the extent that food-web dynamics affecting fish biomass is affected by exchanges of fine particulate organic matter (of either aquatic or terrestrial origin) and aquatic organisms (fishes in particular) between the Guadalupe River channel and oxbow lakes during high flow pulses.  This project, funded by the Texas Parks and Wildlife Department, is designed to reveal relationships between flow, lateral connectivity, and food-web dynamics in the lower Guadalupe River and oxbow lakes within its floodplain.  The project is analyzing ratios of stable isotopes of carbon and nitrogen to estimate production sources supporting fish biomass at multiple sites in the river channel and floodplains under contrasting flow conditions.

Flow dependent species: life history and habitat associations in Texas Gulf Coast rivers

Kirk Winemiller, Tony Rodger, Corey Krabbenhoft, Carmen Montaña, Kevin Conway, Kevin Mayes (TPWD)

Given that life history information has and will continue to be used to develop instream flow recommendations, a research strategy that targets species that are known to be sensitive to flow and that occur in multiple basins will provide the most efficient approach for providing insight beyond the basins and populations studied.  This detailed distribution, habitat use, and life history information will be used to develop instream flow recommendations for the conservation of fish species classified as fluvial specialists.  The focus of this project is the life history of cyprinid fishes identified as fluvial specialists and responses of these species to flow variation in two major Texas rivers, the Trinity and Brazos.  Species patterns of distribution and abundance through time are being documented by analysis of data from recent field surveys and historical records archived in natural history collections.  The field research examines reproductive ecology (timing and habitat for spawning, early life stage development, and abundance patterns) as well as size-at-age data for estimation of growth rates.  Combining data on life history and habitat use will allow estimation of critical habitats during different life stages and how aspects of the flow regime influence the reproduction, survival, and growth of the focal species.  This project involves collaboration with funding by the Texas Parks and Wildlife Department.

Helpful Websites with Information about Texas Environmental Flows Programs:

Dr. Winemiller’s River Science Fact Sheet (PDF)

Dr. Winemiller on Environmental Risk Management (PDF)

Review of Desk-top Methods for Establishing Environmental Flows in Texas Rivers and Streams (PDF)

Biological Overlay (Environmental Flow Analysis) for the Sabine & Neches River Basins and Sabine Lake Estuary

Environmental Flows for Caddo Lake

Nutrients and Biological Responses

Development of Biological Indicators of Nutrient Enrichment for Application in Texas Streams (Oct 2009) (PDF)

Recreational Use Attainability Analysis

DiverRecreational Use Attainability Analyses (RUAA) are scientific assessments carried out on streams to determine whether the existing and/or attainable recreational use for a particular classified or unclassified water body might be different than the presumed recreational use as specified in the Clean Water Act. RUAAs  generally include physical, chemical, and biological evaluations to determine what factors impair attainment of designated uses and provide information to determine what uses are appropriate and feasible for the water body in question.  Important factors in such analyses include naturally occurring pollutant concentrations, anthropogenic sources of pollution, water depth, hydrological modifications, and natural physical characteristics of streams that could impair use. In addition, RUAAs typically assess the current uses (recreation and otherwise) of the water bodies under evaluation.

RUAA Studies in Texas River Basins

Leon river

Over the past several years, the Aquatic Ecology Lab has assisted the Texas Commission on Environmental Quality (TCEQ) by conducting RUAAs for river and stream segments throughout the state.  Following TCEQ’s 2009 Recreational Use Attainability Analysis Procedures, team members consult landowners, interview recreational users, and collect environmental data.  This information is used by the Water Quality Standards Team within the TCEQ to potentially classify or reclassify streams in the categories of Primary Contact Recreation, Secondary Contact Recreation 1, Secondary Contact Recreation 2, and Noncontact Recreation.  Field surveys and data collection for the RUAA projects are managed by Dr. John Baker,  Research Associate in the Aquatic Ecology lab.  

Map of Brazos river basin

Texas Commission on Environmental Quality (TCEQ) Surface Water Quality Website: http://www.tceq.state.tx.us/nav/eq/eq_water.html

Surveying Recreational Uses in Texas


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