County: Harris
Parameters: Copper, water toxicity, sediment
toxicity, temperature
River Basin: San Jacinto River
Segment: 1006A
Background and Goals
Water quality testing prior to 1999 found that Patrick Bayou
might not be able to support a healthy aquatic community. Several
conditions were found that exceeded criteria established to protect
aquatic life and general uses of the water body:
- high average concentrations of dissolved copper
- water toxicity
- sediment toxicity
- high water temperatures
Patrick Bayou is a small tidal tributary of the Houston Ship
Channel. The non-tidal portion of Patrick Bayou lies south of SH
225, is largely concrete lined, and serves as drainage for the City
of Deer Park. Freshwater flow from the watershed is ephemeral.
Immediately downstream (north) of SH 225, the first 1.3 km of the
bayou flows through either concrete culverts or a gunite-lined
channel. The bayou downstream of this point has earthen banks and a
soft mud bottom. Most of the bayou north of SH 225 is tidally
influenced to some degree. The bayou is affected by industrial and
municipal wastewater discharges and by stormwater runoff from
industrial and urban areas.
The goal of the project is to restore the quality of the bayou
to conditions that will support a healthy aquatic community. The
lead organization working with the TMDL Program is a consortium of
permittees that discharge to Patrick Bayou. The member
organizations are the City of Deer Park, Lubrizol, Oxy Vinyls,
Praxair, Rohm and Haas Texas, and Shell Inc. Parsons Water &
Infrastructure Inc. has performed technical work for the
project.
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Project Status and
Implementation
Analyses of data collected through April 2001 indicate that
water toxicity and dissolved copper no longer exceed water quality
standards due to control actions previously implemented by
dischargers. Those controls will continue, so no TMDL allocations
to address water toxicity or dissolved copper will be prepared.
In September 2002, Patrick Bayou was added to the Superfund
National Priority List. The federal Superfund program has begun to
plan for remediation of sediment toxicity; the need for a TMDL will
be addressed when Superfund information and plans are
developed.
There are significant uncertainties and difficulties regarding
future TMDL directions regarding water temperature and sediment
toxicity. The major source of heated-water discharge has closed
since the study, and bayou temperatures have not been observed to
exceed the temperature criterion since then. In addition, one
interpretation of the federal Clean Water Act requires that
regulation of thermal discharges should be based on whether water
temperature is preventing the existence of a “balanced
indigenous population” of aquatic organisms, rather than on
simple water temperature measurements. The tidal portions of
Patrick Bayou support abundant wildlife in the form of birds (such
as ducks, shorebirds, roseate spoonbills, ospreys), turtles, and
fish. Although benthic communities may be affected or limited, it
is not clear why. Standard biometrics for estuarine benthic
communities are not available as benchmarks for such
determinations.
Current scientific techniques are unable to determine which of
numerous chemicals or metals present in the sediment cause sediment
toxicity in lab tests, nor can analytical techniques determine
whether the primary limiting factors for benthic organisms are
chemical, thermal, or natural (such as highly variable salinity and
flow). It is not clear to what extent sediment chemistry reflects
current discharges amenable to TMDL control, versus historical
residue from 80 years of industrial production surrounding the
bayou that might be more suitably addressed by remedial
programs.
The TCEQ will continue to work towards resolution of water
quality issues in Patrick Bayou. Temperature conditions will be
monitored for some time to assess the effect of the closure of a
major heat discharger. Progress of the Superfund project will also
be monitored to determine if further action will be needed.
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Public
Participation
An advisory
panel was established to advise the TCEQ on this project. Find out
more about meetings and membership of the advisory group.
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For More Information
For additional information regarding this project, please
contact Larry Koenig, at 512/239-4533. Or send an e-mail to tmdl@tceq.state.tx.us, and
reference the Patrick Bayou TMDL Project in the subject line.
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