Transcript No Slide Title

Water Quality and Environmental Flows
Maintaining Quantity for Quality’s Sake
Presented By: Jennifer Benaman
Quantitative Environmental Analysis, LLC
November 1, 2005
Project Overview
Water for rural
communities
Lake
Buchanan
Higher water levels
in Highland Lakes
Austin
San Antonio
Water for agriculture
Freshwater inflows for
Matagorda Bay
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Maintain higher water levels
in Highland Lakes
How will the project conserve and
develop 330,000 acre-feet of water?
Build Off-Channel Storage
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Use Groundwater for Agriculture
when Surface Water Insufficient
Wharton
Conserve
Agricultural
Irrigation Water
Bay City
Provide beneficial
Inflows
Matagorda Bay
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State Legislative Requirements
 As per HB 1629, the project must
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Protect and benefit basin interests
Be consistent with state regional water plans
Provide inflows adequate to maintain ecological health and
productivity of Matagorda Bay
Maintain current instream river flow protections
Ensure San Antonio practices stringent conservation
measures
Provide broad public and scientific review process
Benefit stored water levels in Lakes Travis and Buchanan
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Environmental Study Teams
 Matagorda Bay Health
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Respond to the mandate that bay inflows remaining after
any Project diversions will be adequate to maintain the
health and productivity of the Matagorda Bay System
 Aquatic Habitat/Blue Sucker
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Study the impact of the LSWP on the riverine habitats in
the river below Austin
 Water Quality
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Study the impact of the LSWP on the water quality of the
river
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Matagorda Bay Health Evaluation
 Detailed analysis of inflows to the bay system, both from the Colorado
River and the coastal drainage system into the bay which stem in part
from return flows from irrigation areas
 Salinity modeling of the bay system including the marsh systems on
the northern boundary of Matagorda Bay and East Matagorda Bay
 The effects on bay habitat of various freshwater inflow regimes
 The effects of changes in inflow on bay food supply (nutrients and
sediment)
 Development of statistical relationships between inflow and biota
 Synthesis of these various components of “bay health”
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River Water Quality Implications
 Current LCRA Water Management Plan
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Release stored water from Highland Lakes for downstream
irrigators during summer
Net effect: summer flows higher than “natural”
 Potential Effect of LSWP
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Irrigators obtain water from local (downstream) sources.
More frequent low flows in summer
Changes in the timing, duration, and
frequency of low flows may affect water quality
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River Model Approach
 Use state-approved QUAL-TX
 Focus on critical low flow condition
 Expand TCEQ grid
 Collect additional data to
constrain model
 Calibrate to new data,
scale to warmer
temperatures
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Longhorn Dam
Smithville
TCEQ
grid
Future critical condition anticipated
to be in summer
 Perform future simulations in coordination with
expected flow regime
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New
grid
New Data Collection
Water quality under “low-flow”/warm conditions
Dye tracer for hydraulic
characterization
Diel DO for daily dissolved
oxygen fluctuations
Bay habitat mapping
Salinity data for model development in the bay
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For Additional Information
www.lcra.org/lswp
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