per year. This analysis was made using original
area-capacities under Scenario 3, which assumes full diversion amounts and no
return flows.
The COH currently holds 168,000 acre-feet of appropriated
water rights from Lake Houston and owns the lake outright. Therefore, this application requests the
appropriation of the 32,500 acre-feet per year of firm yield remaining in Lake
Houston. No return flows are anticipated
to the San Jacinto River or its tributaries from the portion of the additional
appropriation granted to the SJRA. The
application indicates that diversions for the COH facilities may be returned to
the San Jacinto River or it tributaries through any of the City’s wastewater treatment
plants.
TPWD Review
TPWD reviewed the application with regard to potential
impacts from the proposed increase in firm yield to rare and unique species and
biotic communities, water quality, instream uses, and
freshwater inflows. TPWD also considered
potential cumulative effects on natural resources of the San Jacinto River
system that may result from an increase in the firm yield of Lake Houston. Staff concerns include, but are not limited to, impacts to rare
species, the quantity of water available for firm yield, the potential degradation
of aquatic and riparian habitats downstream of Lake Houston, the reduction of instream flows below Lake Houston and the subsequent impact
on water quality, and the alteration of the frequency and volume of freshwater
inflows to the Galveston Bay System.
Rare Species
The Texas Biological and Conservation Data System (BCD) was searched for occurrences of rare species or natural
communities in the general vicinity of the proposed project. The BCD information is based on the best data
currently available to the state regarding threatened, endangered, or otherwise
sensitive species. According to the BCD,
there are several
occurrences of the American bald eagle (Haliaeetus
leucocephalus), a federal and state listed
threatened species, and rare plant communities along the West Fork San Jacinto
River and Lake Houston. The
project as proposed with diversions at the Lake Houston Dam will not effect the presence of the American bald eagle or the rare
plant communities.
Water Availability
The analysis of the updated WAM (2002) performed by the San
Jacinto River Authority utilized the original area-capacities of Lake
Houston. Considering the amount of sand mining activity that
occurs in the San Jacinto River Basin and the fact that Lake Houston was
constructed more than 50 years ago, the storage capacity of the reservoir has
undoubtedly decreased due to sedimentation. Thus, using the original area-capacities for
Lake
Houston to evaluate water availability may result in an
overestimate as the volume of the reservoir has actually decreased.
Lake Houston was completed in April 1954 with a reported
total storage capacity of 158,550 acre-feet and a conservation storage capacity
of 147,920 acre-feet (Burns, pers. comm., 2005). In 1966, Ambursen Engineering
Corporation surveyed Lake Houston and found a total storage capacity of 146,769
acre-feet, which represents a 7.4% decrease in total storage capacity since
April 1954. In February 1994, the TWDB
surveyed Lake Houston and calculated a total storage capacity of 133,990
acre-feet and a conservation storage capacity of 128,863 acre-feet. This represents an 8.7% decrease in storage
capacity from 1965 to February 1994. Considering
the last survey was performed more than 10 years ago, the total decrease in
storage capacity of Lake Houston from 1954 to present is at 8.7% and perhaps as
much as 20%. Overestimation of storage capacity will lead to
shortages during dry times that will adversely impact instream
flows and freshwater inflows. As such,
the original area-capacities for Lake Houston are no longer valid and should
not be used in calculating current water availability.
TPWD staff recommends the SJRA reanalyze the updated WAM
simulations using the updated area-capacities from the 1994 TWDB survey. The updated storage capacity numbers more
accurately reflect the current conditions within Lake Houston and will
therefore provide the applicant with a better estimate of dependable firm yield
from Lake Houston.
Instream Uses
The San Jacinto River downstream of the Lake Houston Dam is
tidal in nature and is designated as Segment No. 1001 in the State of Texas
Water Quality Inventory (1996). Segment
No. 1001 is 17 miles in length starting from a point 100 meters downstream of
IH 10 in Harris County upstream to the Lake Houston Dam. Designated water uses for this segment are
contact recreation and high aquatic life.
This segment of the San Jacinto River receives a large amount of
recreational use and provides freshwater that supports wetland habitats (i.e.
cypress swamps, emergent wetlands, forested wetlands, mudflats, and open water)
and a relatively diverse fish community.
Instream flows also aid in the assimilation of
urban stormwater runoff and point source discharges
associated with the Houston Ship Channel downstream. Primary concerns associated with reduced instream
flows in the San Jacinto River downstream of Lake Houston include an increase
in the degree and frequency of saltwater encroachment, loss or alteration of
aquatic and riparian habitats due to saltwater intrusion, and degradation of
water quality that could potentially result in the nonsupport of TCEQ
designated water uses.
Overflows from the Lake Houston Dam occur through a spillway
when water levels are greater than 44.44 ft msl. TPWD staff is concerned about the effect
diversions will have on the frequency with which water flows over the
spillway. Because historical data on
discharges over the Lake Houston spillway is not readily available, it is
difficult to assess the degree to which spills will be altered as a result of
the increase in firm yield. The 32,500
acre-feet of water requested by the applicant equals a 19% increase in firm
yield from Lake Houston. Such an
increase in firm yield with corresponding reduction in downstream flows could
have significant impacts on the environmental uses of the San Jacinto River
downstream of Lake Houston.
The San Jacinto River downstream of Lake Houston is fringed
by a relatively significant amount of freshwater wetlands, including extensive
cypress swamps upstream of Highway 90 and a 456-acre tract of mitigation
property located in an area known as Banana Bend. In addition, the river supports a relatively
diverse fish community composed of both freshwater and estuarine species. Based on an assessment of the fish community,
Luedke (1994) characterized this section of the San
Jacinto River as the least impacted tributary of the Houston Ship Channel based
on (1) the low percentage of tolerant species, (2) the low percentage of
striped mullet, gizzard shad, Rio Grande cichlid, and spotted gar and (3) the
high number of game fish species. Due to
the types of wetland vegetation (i.e. bald cypress, Taxodium
distichum) and freshwater fish species (i.e.
white bass, crappie, pirate perch) present downstream of Lake Houston, it is
apparent that surface saltwater inundation has not occurred in the area for an
extended period of time.
Analysis of water quality data from August 1982
(Kirkpatrick, 1986), when no discharge was occurring over the spillway of the
Lake Houston Dam indicates the presence of a saltwater wedge extending just
upstream of the Banana Bend area. In
contrast, water quality data from February 1985 (Kirkpatrick, 1987), a time
when water was discharging over the spillway of the dam, does not indicate the
presence of a saltwater wedge anywhere within the 17-mile stretch of Segment
1001. Luedke
(1994) reported similar findings while assessing the fish populations of the
major tributaries to the Houston Ship Channel.
Fish collections at Banana Bend in July 1991, a time of low flow
conditions, yielded 6 predominantly estuarine species. Sampling at the same site in January 1992, a
period of high flow conditions, resulted in 14 species of fish, including both
freshwater and estuarine species.
A
significant long-term decrease in the volume of freshwater that crests the
spillway of the Lake Houston Dam would likely allow the saltwater wedge to
encroach further upstream and increase surface salinities in the Banana
Bend area and possibly upstream of Highway 90.
Riparian and aquatic communities associated with the San Jacinto River
downstream of Lake Houston cannot withstand increased salinities for an
extended period of time. Because
freshwater wetlands along the Gulf Coast support significant habitat for
breeding and wintering waterbirds and support
numerous species of amphibians, reptiles, fish, and mammals, the loss or
alteration of these wetlands could cause a significant adverse impact on
regional wildlife populations.
Additionally, because freshwater wetlands can improve water quality by
filtering out sediments, nutrients, and pollutants, their loss or alteration
could effectively reduce the water quality of the San Jacinto River downstream
of Lake Houston.
Water Quality
Additional
diversions from Lake Houston that would decrease instream
flows downstream of the dam could also significantly degrade water quality
within the San Jacinto River and the Galveston Bay system. The San Jacinto River joins the Houston Ship
Channel (TCEQ Segment 1005) approximately 17 miles downstream of the Lake
Houston Dam. Segment 1005 of the Houston
Ship Channel is classified as water quality limited and is affected by urban stormwater runoff and major point source discharges. By decreasing the volume of freshwater that
enters the system through the San Jacinto River, it is possible that tidal
influences will push return flows from the Houston Ship Channel upstream into
the San Jacinto River during low flow periods.
This would degrade water quality within the San Jacinto River downstream
of Lake Houston and possibly result in the failure of this segment to meet its
TCEQ designated uses. Furthermore, freshwater inflows
to the Galveston Bay system from the San Jacinto River Basin would be dominated
by return flows and urban stormwater runoff. This could have major ecological impacts on
the Galveston Bay system and the commercial and recreational fishing industries
it supports.
In order to protect the instream
uses and biotic communities associated with the San Jacinto River downstream of
Lake Houston that depend on the quantity and quality of freshwater resources
available, a restriction should be imposed that will maintain a predominantly
freshwater habitat. TPWD staff recommends
that any diversions associated with an increase in firm yield be limited to
those times when streamflow downstream of Lake
Houston is sufficient to maintain a specific conductance of 2,000 µmhos as
measured within three feet of the water’s surface at Banana Bend Park on the
San Jacinto River.
Freshwater Inflows
The TPWD has done extensive research into the freshwater
inflow needs of the Trinity – San Jacinto estuary, including Galveston Bay
(Lee, et al., 2001). The research is the
result of TWC §16.058 that mandates that the TPWD and the Texas Water
Development Board (TWDB) determine the bay conditions necessary to support a
sound ecological environment. This
includes the effects of and needs for freshwater inflows to Texas bays and
estuaries. In addition, TWC §11.147(b)
directs the TCEQ to include in water right permits, to the extent practicable
when considering all public interests and the studies mandated by TWC §16.058
as evaluated under TWC §11.1491, those conditions considered necessary to
maintain beneficial inflows to any affected bay and estuary system. Freshwater inflows from river, streams, and
local runoff maintain the salinity gradients, nutrient loadings, and sediment
inputs needed to support a healthy and productive estuary.
Working cooperatively, the TPWD and TWDB estimate that the Trinity-San Jacinto
estuary requires 5.22 million a-ft/yr of freshwater inflows to maximize harvest
of oysters, white and brown shrimp, blue crabs, red and black drum, spotted sea
trout, and flounder. Annual
freshwater inflows of approximately 4.16 million a-ft are recommended to allow
acceptable levels of harvest. In an
effort to determine if the modeling estimates were reasonable, TPWD analyzed
historical fish community data. TPWD’s verification and analysis indicate that a freshwater
inflow of between 4.16 and 5.22 million a-ft/yr with an appropriate seasonal
distribution would allow the ecological health and productivity of the bay to
be protected in the future (Lee et al., 2001).
The San Jacinto River Basin contributed 28% of the average
annual freshwater inflow to the Galveston Bay system during the period
1941-1990 (TWDB, 2004). Approximately
50% of this freshwater inflow is from water that spills over the Lake Houston
Dam, which is largely composed of return flows during drier months. Based on these percentages, the median
monthly contribution to the Galveston Bay system from Lake Houston for the
period 1941-1990 in acre-feet is as follows:
|
Jan
|
Feb
|
Mar
|
Apr
|
May
|
June
|
July
|
Aug
|
Sept
|
Oct
|
Nov
|
Dec
|
|
97,929
|
132,507
|
91,392
|
88,550
|
178,318
|
117,558
|
47,653
|
31,537
|
46,234
|
35,265
|
49,210
|
87,752
|
TPWD staff recommends an inflow within the range of Min Q to
MaxH values as the freshwater inflow needed to
fulfill the biological needs of the Galveston Estuary on a seasonal basis (Lee,
et al., 2001). MinQ
is defined as the minimal inflow level needed to maintain both the historical
salinity gradients and biological productivity, while MaxH
constitutes a flow to the estuary that would maximize biological productivity
within the modeling constraints. By
using the same percentages as above, the range of values from MinQ to MaxH for contributions
from Lake Houston to the Galveston Estuary can be calculated. These values in acre-feet for the period
1941-1990 are as follows:
|
|
Jan
|
Feb
|
Mar
|
Apr
|
May
|
June
|
July
|
Aug
|
Sept
|
Oct
|
Nov
|
Dec
|
MinQ
|
21,070
|
30,338
|
50,946
|
49,364
|
95,158
|
62,734
|
32,578
|
21,560
|
46,228
|
35,266
|
49,210
|
87,752
|
|
MaxH
|
21,070
|
21,728
|
91,392
|
88,550
|
178,318
|
117,558
|
29,610
|
19,600
|
14,420
|
11,004
|
49,210
|
87,752
|
Analysis of these numbers indicates that median monthly
inflows and TPWD’s recommended inflow values (MinQ and MaxH) are lowest during
the months July through October.
Similarly, analysis of gage height data from the Lake Houston Dam from
1977-1999 indicates that July through October are also the most frequent months
when lake levels are below the spillway.
While drought situations during drier summer months are inevitable, TPWD staff is concerned that the
cumulative impact from this application and others submitted by the SJRA and
the City of Houston will exacerbate periods of no flow over the Lake Houston
spillway and decrease freshwater inflows to the Trinity-San Jacinto estuary.
Because historical data on discharges over the Lake Houston
spillway was not provided by the applicant it is difficult to assess the
adequacy of the quantity and quality of flows remaining after the proposed
diversions to meet instream uses and bay and estuary
freshwater inflow needs. The burden of
assessing the alteration of flows after diversions is placed upon the applicant
according to TAC §295.112(b) and TWC § 11.042(b) (see attachments). This includes an assessment of the adequacy
of flows remaining after the proposed increase in firm yield to meet instream uses and bay and estuary freshwater inflow
needs. Without this information, it is
difficult for TPWD staff to fully assess impacts associated with an increase in
firm yield from Lake Houston. Upon
receiving the required information, both TCEQ and TPWD staff will be able to
properly evaluate the request with regard to protecting instream
uses of the San Jacinto River and freshwater inflows to Galveston Bay.
In the absence of such information, TPWD staff recommends a streamflow restriction be imposed on diversions associated
with this application to protect freshwater inflows. The contributing flow that has historically
spilled over Lake Houston is estimated to be 14% of the total freshwater
inflows into the Trinity-San Jacinto estuary.
Based on TPWD’s studies of the estuary, the
contributing flows in acre-feet from the Lake Houston drainage are:
|
|
Jan
|
Feb
|
Mar
|
Apr
|
May
|
June
|
July
|
Aug
|
Sept
|
Oct
|
Nov
|
Dec
|
MinQ
|
21,070
|
30,338
|
50,946
|
49,364
|
95,158
|
62,734
|
32,578
|
21,560
|
46,228
|
35,266
|
49,210
|
87,752
|
|
MaxH
|
21,070
|
21,728
|
91,392
|
88,550
|
178,318
|
117,558
|
29,610
|
19,600
|
14,420
|
11,004
|
49,210
|
87,752
|
Any flow restriction should be conditioned on a freshwater
inflow value within the range of Min Q to MaxH to
fulfill the biological needs of the Galveston Estuary on a seasonal basis. Maintenance of freshwater inflows within the
recommended range should also suffice to maintain current instream
uses of the San Jacinto River downstream of Lake Houston and negate the need
for a restriction based on maintaining freshwater habitat below Lake Houston.
Recommendation
To properly ensure that both environmental and human needs
are satisfied would require the San Jacinto River system to be operated in a
manner that does not adversely impact the frequency with which water crests the
spillway at Lake Houston. Addressing
environmental concerns on a permit-by-permit basis cannot effectively achieve
this goal. The cumulative impact from
this and other pending applications could prove detrimental to aquatic and
riparian habitats in the San Jacinto River downstream of Lake Houston and to
the Galveston Bay system. The
formulation of a management plan for the San Jacinto River Basin that addresses
environmental needs while developing new sources of water would be the most
efficient method for providing water for both environmental and human needs.
In the absence of such a management plan, TPWD staff
recommends the following restrictions:
1) The applicant should
reassess the WAM simulations using the updated area-capacities for Lake Houston
from the 1994 survey performed by the TWDB.
2) A flow restriction be imposed conditioned on a freshwater inflow value within
the range of Min Q to MaxH to fulfill the biological
needs of the Galveston Estuary on a seasonal basis.
3) If the
aforementioned streamflow restriction is not imposed,
then diversions associated with the increase in firm yield should be limited to
those times when streamflow downstream of Lake
Houston is sufficient to maintain a specific conductance of 2,000 µmhos, as
measured within three feet of the water’s surface at Banana Bend Park on the
San Jacinto River, in order to protect the biotic resources that depend on the
quantity and quality of freshwater resources available.
If you have any questions regarding these comments, please
contact Chad Norris at (512) 912-7161.
Sincerely,
Chad W. Norris
Water Resources Branch
Burns, Randall.
2005. Personal
communication. Texas
Water Development Board, Surface Water Section, Austin, Texas.
Kirkpatrick, Jeff.
1986. Intensive Survey of the
Houston Ship Channel System: Hydrology, Field Measurements, Water
Chemistry. IS 86-10. Texas Water Commission,
Austin, Texas. 131 pages.
Kirkpatrick, Jeff.
1987. Intensive Survey of the
Houston Ship Channel System: Hydrology, Field Measurements, Water Chemistry,
Sediment Chemistry. IS
87-09. Texas
Water Commission, Austin, Texas. 90 pages.
Lee, W., D. Buzan,
P. Eldridge, and W. Pulich Jr. 2001.
Freshwater Inflow Recommendation for the Trinity-San Jacinto Estuary of
Texas. Texas Parks and
Wildlife Department. Coastal Studies Program.
Austin, Tx. 24 pages.
Luedke, Mark. 1994.
Fish Populations in the Major Tributaries of the Houston Ship Channel:
Segments 1001, 1006, 1007, 1013, 1017. AS-26/SR. Texas Natural Resource Conservation Commission. 32 pages.
Texas Water Development Board. 2004.
Trinity-San Jacinto Estuary Freshwater Inflows (Galveston Bay). On the Internet at: http://hyper20.twdb.state.tx.us/data/bays_estuaries/TxEmp/galvtable.htm
Attachment A
RULE §295.112
(a) The purpose of this section is to provide the
application content requirements for a bed and banks authorization under Texas
Water Code §11.042(b).
(b) A person who has discharged or intends to discharge
groundwater-based effluent into a stream or watercourse and wishes to divert
and use the discharged water shall submit an application with the commission
containing the following information:
(1) the name, mailing
address, and telephone number of the applicant;
(2) the name
of the stream and the locations of the point of the existing or proposed
discharge and diversion as identified on a USGS 7.5 minute topographical
map(s);
(3) the
source, amount, and rates of the existing or proposed discharge and diversion;
(4) a
description of the water quality of the water discharged or proposed to be
discharged and the permit number and name of any related discharge permit;
(5) the date
of initial discharge of the groundwater into the watercourse or stream, if
applicable, and any related records of discharge periods, points, amounts and
rates;
(6)
the estimated amount of water that will be lost to transportation, evaporation,
seepage, channel or other associated carriage losses from the point of
discharge to the point of diversion;
(7) an
assessment of the adequacy of the quantity and quality of flows remaining after
the proposed diversion to meet instream uses and bay
and estuary freshwater inflow needs; and
(8) any other
information the executive director may need to complete an analysis of the
application.
(c) Nothing in this section shall be construed to
affect an existing project for which all required water rights and reuse
authorizations have been granted by the commission prior to September 1, 1997.
(d) The method and calculation of carriage losses
under this section shall be subject to the review and approval of the executive
director.
Attachment B
TWC § 11.042. Delivering Water Down
Banks and Beds
(a)
Under rules prescribed by the commission, a person, association of persons,
corporation, water control and improvement district, water improvement
district, or irrigation district supplying stored or conserved water under
contract as provided in this chapter may use the bank and bed of any flowing
natural stream in the state to convey the water from the place of storage to
the place of use or to the diversion point of the appropriator.
(b) A
person who wishes to discharge and then subsequently divert and reuse the
person's existing return flows derived from privately owned groundwater must
obtain prior authorization from the commission for the diversion and the reuse
of these return flows. The authorization may allow for the diversion and reuse
by the discharger of existing return flows, less carriage losses, and shall be
subject to special conditions if necessary to protect an existing water right
that was granted based on the use or availability of these return flows.
Special conditions may also be provided to help maintain instream
uses and freshwater inflows to bays and estuaries. A person wishing to divert
and reuse future increases of return flows derived from privately owned
groundwater must obtain authorization to reuse increases in return flows before
the increase.
(c)
Except as otherwise provided in Subsection (a) of this section, a person who
wishes to convey and subsequently divert water in a watercourse or stream must
obtain the prior approval of the commission through a bed and banks
authorization. The authorization shall allow to be diverted only the amount of
water put into a watercourse or stream, less carriage losses and subject to any
special conditions that may address the impact of the discharge, conveyance,
and diversion on existing permits, certified filings, or certificates of
adjudication, instream uses, and freshwater inflows
to bays and estuaries. Water discharged into a watercourse or stream under this
chapter shall not cause a degradation of water quality to the extent that the
stream segment's classification would be lowered. Authorizations under this
section and water quality authorizations may be approved in a consolidated
permit proceeding.
(d)
Nothing in this section shall be construed to affect an existing project for
which water rights and reuse authorizations have been granted by the commission
before September 1, 1997.