Environmental Restoration and Protection Areas Feasibility Study: Comal Springs

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Environmental Restoration and Protection Areas

Feasibility Study: Comal Springs

TPWD
Comments

March
2
3
, 2011


TPWD staff has had the opportunity to review the Environmental Restoration and Protection
Areas Feasibility Study: Comal Springs report, which
was prepared by Bio
-
West, Inc. for the
Edwards Aquifer Recovery and Implementation Program.

S
ection 2.
0 describes the Environmental Background of Comal Springs, including a summary for
each species.
TPWD supports the inclusion of
the Comal Springs salamand
er

even though it is
not Federally
-
listed

given this species occupies habitats in close association with the Comal
Springs riffle beetle.

Section 3.0 addresses Stakeholder Interaction and
identifies specific concerns raised by
stakeholders.

TPWD supports the
formation of a review team or future subcommittee to oversee
ERPA activities
,
recommend possible alternatives
, and assist in study design, data collection, and
data analysis
.
The review

team or subcommittee should be composed of ex
perts
from multiple
disciplines with an emphasis on those familiar with the listed species, such as an i
nvert
ebrate

biologist,
fish biologist,
hydrogeologist, ge
omorphologist, and others.
Such a team will provide
broad perspe
ctives in developing ERPA activities,

may help reduce costs through collaborative
efforts

and applied research activities
,

and will help ensure acceptance by all involved in the
EARIP

process
.

It would also be good to
identify partnerships

for implementation of the ERPAs
to share in the cost
and work duties

given the limited funding

and broad scope of questions that
remain unanswered regarding the needs of the listed species.

Section 5.0 outlines the ERPA component description and conceptual design. Each component
of the proposed ERPA’s is ad
dressed below.

Section 5.1 addresses restoration. The primary resto
ration activity proposed is the establishment
of native vegetation and removal of non
-
native vegetation in key, sustainable areas such as the
Old Channel and Landa Lake. TPWD staff agrees that removing non
-
native vegetation and
establishing native vegetat
ion is important, but questions the long
-
term sustainability of
maintaining native vegetation in the Old Channel given the abundance of non
-
natives
currently
present upstream in Landa Lake. While the removal of non
-
native vegetation
from

Landa Lake
would
represent a monumental task,
it is a worthwhile effort
. F
ailure to
remove the source area
of non
-
native vegetation places the proposed
Old Channel ERPA reach

in perpetual jeopardy of
revegetation of
non
-
native
species
.
While a flow bypass is proposed to p
rotect the upper portion
of the Old Channel,
unless properly sized
,

the capacity of such a bypass will not protect against
large floods
,

scouring
,

and the immigration of non
-
native vegetation
.


An additional benefit to removing non
-
native vegetation from Landa Lake, assuming native
vegetation is established in its place, is the
potential
bolstering of fountain darter populations. It
is

well established

that fountain darters prefer
cover in the f
orm of vegetation and favor
native
vegetation, so it is
possible that

establishing native vegetation
in the lake
will result in an
increase in darter numbers. Efforts to remove non
-
native vegetation could begin systematically at
the headwater confluence wi
th Blieders Creek and
work downstream.
Removal of non
-
native
vegetation will need to be on
-
going and require short and long
-
term monitoring to be successful.
T
rained volunteers and University students
might be available
as fr
ee

or inexpensive

labor for
large
-
scale removal.


It should
also
be noted that the City of New Braunfels has filed with USFWS and USACE for a
permit to
address

sedimentation issues with the spillway
that empties into the head of the Old
Channel and erosion issues with the
dam
at the head of the spring
-
fed
swimming pool.
S
edimentation at the spillway
and erosion at the dam
,

over the last decade
or more,

has resulted
in
the spillway
lying at a higher elevation than the dam, which
is currently only an inch or two
above normal poo
l level
(personal communication, Nathan Pence, City of New Braunfels)
. Th
e
City’s
project proposes

to raise the dam elevation and lower the spillway so
that
they function
as
originally designed
. Currently, the dam is overtopped several times a year

and

t
he water enters
the spring
-
fed pool
before draining

into the Old Channel (personal communication, Nathan
Pence

(
City of New Braunfels). If the
project

is
completed
, the spillway, which is located at the
head of the Old Channel, would periodically introduc
e higher flows to the Old Channel and
compromise the ability to manage flows and protect habitat in the Old Channel

as proposed
.



Section 5.2

addresses protection

in the form of native aquatic vegetation maintenance and flow
-
split management
.

TPWD staff agrees that active monitoring and maintenance will be required
to protect native vegetation establishment efforts

in the Old Channel. TPWD staff supports
focusing initial efforts on the Old Channel
, but views this a
s an area to be protected t
hrough
maintenance

as well as a pilot study to inform broader efforts
.
Section 5.2.2

addresses flow
-
split
management in the Old and New Channels.
The purpose of flow split management is to use
culverts at
the
head of the Old Channel as a tool to protect na
tive vegetation establishment efforts
in the Old Channel and to maximize the quality of habitat in the Old Channel.
Under t
he
proposed flow
-
split, the Old Channel would receive 20 cfs

when the total springflow is 30 cfs.

The desired goal is to maintain 40
-
80 cfs of flow at all times.
Hardy (2011) indicates that 20 cfs
in the Old Channel will provide approximately 75% of the maximum available fountain darter
habitat from a physical habitat perspective

and that 3 of the 4 identified thermal thresholds are
no
t exceeded
.

Section 5.2.4 addresses the proposed spring run connectivity ERPA. Hardy (2011) is quoted as
stating that “we believe the empirical data on riffle beetles demonstrates their persistence within
spring runs and Landa Lake over the past two deca
des strongly supports that they should be
adequately protected over the proposed flow regime.”
While Comal Springs
r
iffle
b
eetles have
persisted in these habitats, the impact of
the drought of record
on the population is unclear as no
data was gathered pr
ior.


Past occupation and persistence does not ensure continued presence
during a repeat of drought of record conditions or worse
.

TPWD staff
is skeptical that

the water quality of
Landa Lake
will be
adequate to support
populations of riffle beetles

under the proposed flow regime
. W
ater quality at the mouth of
spring run 3
declines

during low flow conditions
as
the western springs are reduced until the lake
springs are the sole component of flow (page B
-
22 of Guyton 2004).
In spite of remaining

conc
erns regarding the placement of the proposed diffuser pipes, the possible impingement and
entrainment of organisms in the pump system, and the possible degradation of the remaining
habitat in spring run 3 as a result of pumping Landa Lake water into the
ha
bitat;

TPWD staff
does not oppose this proposed project
.

Section 5.2.5 outlines the Old Channel ERPA. The last paragraph on page 40 states three main
concerns noted in Hardy (2011) regarding this flow regime
:

1)

the potential for aquatic
vegetation die
-
off and subsequent dissolved oxygen (DO) problems in Landa Lake,
2)
the
increase in larval mortality of fountain darters that would likely be experienced, and
3)
the
potential for cool water inflows from springs al
ong the margin of Landa Lake
to flow

down the
New Channel instead of entering the Old Channel.
The Old Channel ERPA and protection area
is proposed, in part, to provide a safeguard in the event
of a
vegetation die off
that

results in
low
dissolved oxygen

levels

in Landa Lake.
T
he third major concern raised by Hardy (2011) in
regards to the short
-
circuiting of cool water inflows down the New Channel as opposed to the
Old Channel could have a significant impact on the success of the Old Channel ERPA and th
e
ability to maintain high quality habitat in the Old Channel.

Before significant time and money is
invested in the Old Channel ERPA, as a whole, it seems prudent to further investigate thermal
dynamics within the water column
, especially as it relates to
lenses

of cooler wate
r
, the Old
Channel culverts, and their relation to varying flows.
This is important because the temperature
of water entering the Old Channel during low flows is a major
factor
in assessing the feasibility
of the proposed ERPAs

and Har
dy (2011) only reports average water column temperatures.

S
ection 5.2.5 (pg 46)

describes
the proposed means of recirculating water to sustain high quality
habitat within the Old Channel
.

P
age 46 states that the “EARIP described flow regime proposes
flows to go as low as 20 cfs within the Old Channel, which strays from a high quality habitat
condition” and that “in order to increase flows back to more optimal conditions within the Old
Channe
l ERPA, some sort of recirculation scheme would need to be implemented.”
TPWD staff
concerns with recirculation include
the
actual
benefits derived from recirculation

(cost/benefit)
,
the
potential for increased water temperatures associated with recirculat
ion
,
the means to divert
and pump more than
50
% of the flow in the channel into a pipe under low flow conditions
,
and
the impingement and entrainment of fountain darters
, among others
.


Hardy (2011) estimated that
a flow of
20 cfs in the Old Channel will
provide approximately 75%
of the maximum available habitat
for fountain darters
from a physical habitat perspective
.

U
nder
extreme ambient temperature conditions
,

the Old Channel ERPA area is projected to maintain
water temperatures
less than

three of the
four temperature thresholds at all times. Analysis of
Table 4 (pg 26), which presents the fountain darter weighted useable area (WUA) in
the
Old
Channel in relation to flow, shows there is only an 8% increase in WUA between 20

cfs

and 40
cfs. This indicat
es
that
there is very little physical habitat benefit derived from increasing flows
from 20
cfs
to 40 cfs.
It

appears as though the only benefit derived from recirculation is an 8%
increase in WUA for fountain darters.
T
his
small increase in fountain darter WUA may not
warrant such

efforts

and

may have negative

habitat

impacts
including

increased water
temperatures
, disturbance of the streambed and banks,

and the impingement and entrainment of
fountain darters

and other spe
cies.


A

major concern for TPWD staff
is the potential for the proposed recirculation project to
increase water temperatures to a point that larval mortality

of fountain darters

will significantly
increase.
Section 5.2.5.1 addresses concerns with water t
emperature modeling. Modeling results
for worst
-
case ambient air temperature
(July 2009)
and maximum Landa Lake input
temperatures (80.6
º

F) are presented

and indicate recirculation does not measurably increase
water temperatures in the Old Channel ERPA re
ach.
However, i
t is not clear
how

“maximum
Landa Lake input temperatures (80.6º F)


were derived or used in the model
.
TPWD staff
assume
s

that it

represent
s

the maximum modeled temperature of Landa Lake water before it
enters the Old Channel.

However, a

review of Hardy (2011) shows temperatures in mid
-
Landa
Lake (upstream of Old Channel culverts) and lower Landa Lake (section that contains Old
Channel culverts) at 30 cfs total discharge range from about 77º to 85º F

and about 79º to 88º F,
respectively.

Thus, it appears as though “maximum Landa Lake input temperatures” were not
derived from Hardy (2011) and the modeled scenario does not represent “worst case.”

Clarification is needed regarding

maximum Landa Lake input temperatures

used in the model
.


Al
so of concern is the
infrastructure needed

to divert and pump more than 50% of the flow in the
channel into a pipe under low flow conditions
as proposed
.
D
etails
of the proposal
describe the
use of three, 12
-
inch screened pipes and a pump system that would create an entrance velocity at
the well screen of 1.5 feet per second (fps). TPWD staff is concerned about the
potential for
impingement and/or entrainment of fountain darters
(adult, juvenile, larval stage, and possibly
eggs), as well as other aquatic organisms, on the well screen. A typical recommendation for
entrance velocities made by resource agencies (TPWD, TCEQ, etc.) to avoid the entrainment and
impingement of organisms

is 0.5 fps
. Due to the size and endangered status of the fountain
darter
, TPWD staff
recommend
s

an entrance velocity less than 0.5 fps
be used in initial plans
.
A
lower intake velocity

would
greatly affect the configuration and number of diversion intak
es that
would be required

at the proposed diversion rate

and suggests that at least nine intakes (as
described) would be needed
.

An increase in the number of diversion structure
s

required
would
have a more significant impact on the bed and banks of the Old

Channel.

Additional concerns with recirculation include the
potential
fouling of the pump
s

and/or well
screen
s

by snails
,

aquatic vegetation
, and debris

and the ramping up time needed to reach 20 cfs
of recirculation
.

F
ouling
of the well screen
s

or pump
s

could cause pulsing or fluctuations in
flow and ultimately result in complete failure of the pump
s

due to clogging.

Pump redundancy
and daily maintenance would be required to minimize fouling impacts.

The report suggests water
would start to be withdrawn
at smaller quantities when total discharge

in the New Channel

is 50
to 60 cfs and slowly be ramped up to reach the desired 20 cfs

rate
. This could result in
significant time
when pumps are
in operation and may also result in times when the pumps are
turned on and the full amount is not needed (e.g. total discharge reaches 45 cfs and then drought
ends).

Section 5.2.5.2 describes the Old Channel experimental channel.
Several aspects of the
experimental channels are of concern including
additional alter
ations

to an already highly
modified system, the
proximity

of the channels
to habitat that has been deemed
Critical Habitat
and
a priority for protection due to its potential for “high quality,” and the design

of the proposed
channels
.
The plans call for
the construction of two channels between the spring
-
fed swimming
pool and the Old Channel.
As described the channels

are estimated to be
15
-
20

feet wide, which
results in an overall width of at least
30

feet. A
30
-
40

foot wide channel would seemingly onl
y
leave a sliver of land between the experimental channels and the Old Channel.
L
arge flood
events
could potentially

alter the
size and configuration of the
experimental channels and erode
the land
separating
the Old Channel and the experimental channels
.

In addition,

lesser flow
events (i.e.

bankfull discharge) are also of

concern
due to their erosional capabilities
. TPWD
staff is concerned that the experimental channels
may

ultimately result in large

unintended

changes

to the Old Channel
that may
ultimately impact the “high quality” habitat

of the Old
Channel
.


Also of concern is the proposal to construct

Comal Springs

riffle beetle habitat by burying a pipe
beneath substrate to provide upwelling. The Comal Springs riffle beetle is known to inhab
it
springs and the area immediately surrounding springs

and

ha
s

never been found far from spring
orifices. The species of riffle beetle currently found in the Old Channel belongs to another genus
known to have

a broad distribution in spring fed creeks and

rivers.
Like other spring endemics,
the
Comal Springs riffle beetle

is adapted to and restricted by the unique conditions found in
spring orifices and the immediate

area.
There is little evidence that indicates the

C
omal
S
prings
riffle beetle

can surviv
e
in habitats outside of its natural range such as
in the experimental
channel
s

or the Old Channel.

Survival of

the Comal Springs riffle beetle
depends on more than

the

upwelling

of water
.
R
esearch performed by B
IO
-
W
EST

in coordination with the San Marcos National Fish Hatchery
and Technology Center

(NFHTC)
on

habitat use of the Comal Springs riffle beetle found the
beetles displayed tendencies for movement downward and toward current
, but
supported

no
statistically sign
ificant conclusions
.
The affinity for aquatic organisms to orient facing into
oncoming current is known as positive rheotaxis and is known to be a trait of riffle beetles as
well as many other aquatic organisms that occupy habitats with swift current.
If
Comal Springs
riffle beetles could survive in downstream habitats, they
would have likely

drifted into and
colonize
d

these habitats at some point since

construction of

the Old Channel.
Spring
-
dwelling
organisms, especially those that also utilize hypogean

(subterranean) habitats, are adapted and
restricted to such habitats. The exact factors that restrict them to these habitats are not known,
but may include an affinity or need for the supersaturation of certain dissolved gases (CO
2

or O
2
)

or food items t
hat are only found in these habitats. USFWS staff at the San Marcos NFHTC

has
experience working with riffle beetles and could likely conduct research into habitat preferences
and utilization of the Comal Springs riffle beetle that would provide insight i
nto
the

factors

that

limit their distribution.


Table 13 asserts that the Old Channel ERPA is not located in a highly erodible or
flood prone
area

and states that only the June 2010 flood caused major damage. According to City of New
Braunfels staff, the
Old Channel receives excess water several times a year through the spring
-
fed swimming pool due to the
previously mentioned
erosion of the dam.

Overbank, bankfull,
and high flow pulse flows are energetic events that can cause severe erosion in unstable sy
stems.
A flow of 80 cfs
as occurred in 2010 is known to cause

extensive scouring in the Old Channel.

F
lows of this magnitude
or greater could have significant impacts on

the experimental channel
and

the Old Channel.
Additional engineering and hydrology studies are needed to determine the
effective discharge of the Old Channel and the experimental channels and the capacity of the
channels for passing 10, 20, 50, and 100 year flood events. Without proper planning and de
sign,
all ERPA efforts in the Old Channel could be compromised by high flow events.

Section 5.2.6 addresses temporary flow screens in Landa Lake. The purpose of temporary
baffles or screens in Landa Lake is to direct flow to deeper areas
to reduce

lake

r
etention time
and keep lake temperatures low. The report concludes that flow screens or baffles are unfeasible
because there were no benefits extended downstream to
the
Old Channel and because
partitioning reportedly created areas with limited circulation

and increased temperatures. TPWD
staff agrees that flow screens are unfeasible and is also concerned about potential impacts flow
screens would
indirectly
have on gill parasite densities.
The reported l
imited circulation and
increased temperature
s

in La
nda Lake
created by the
flow screens are the kind of conditions
likely suitable
to allow the gill parasite to reach high densities
, which could have negative
impacts on fountain darter populations.




Section 5.3 addresses applied research.
As mention
ed previously in these comments, TPWD has
serious reservations about the utility, feas
i
bility, and stability of the proposed Old Channel
ERPAs and the experimental channels.


These concerns override the potential benefits that might
be gained from directed

research and studies using the channels.


TPWD recommends that a
combination of laboratory and field studies continue to be employed to address the habitat, flow,
and life history needs of the species of concern in the Comal spring system as outlined in T
able
14.


If the defi
ci
encies of the ERPAs as proposed can be satisfactorily addressed and mitigated,
then

controlled studies using the experimental channels might be an option to compliment other
research activities.





In the interim, TPWD recommends f
urther investigation into the potential for using
properly
designed laboratory studies and
sites in San Marcos to investigate the questions broached in
Table 14.


While
laboratory
studies

and research

utilizing conditions representative of the San
Marcos system cannot fully replicate conditions in the Comal, they can serve as a safer
alternative and help provide needed information on the needs of the species related to stream
flow, water
chemistry, and

life history
.


As indicated in
Table 14
,

laboratory
studies are not

suitable for
addressing all of the issues
related to

Landa Lake inflow.

While it may be difficult
to simulate low flows
of

10
-
20 cfs

in the

laboratory
,

p
rimary variables of interest related to different low flow volumes
such as

water
temperature and streamflow velocity can be controlled in a lab setting.

In addition, there is a
wealth of information and data already available based on laboratory and racewa
y studies on
several of the species of concern.

A
lternatives to the experimental channels for researching low
flow effects on vegetation decay and physicochemical parameters

also exist
, such as utilizing
ponds at the T
exas
S
tate
U
niversity

campus

to create a microcosm of Landa Lake (personal
communication, Dr. Timothy Bonner, Texas State University Aquatic Station Director) or
utilizing ponds at the San Marcos NFHTC. Similarly, low flow effects on fountain darters and
gill parasites
can be

address
ed through a combination of field studies and laboratory
experiments, providing both statistically significant data and a portrait of actual ecosystem
responses. For instance, the low flow effects on fountain darters could be assessed by
both well
-
designe
d experimental studies that further refine the habitat requirements of fountain darters and
monitoring

their response to low flows in the field.
Conditions in the
upper portion of Landa
Lake at and near confluence with Blieders Creek deteriorate under low

flow
s.

The area could be
used

to
re
-
establish native vegetation and a population of darters during higher flows that could
be monitored (perhaps including mark
-
recapture) as flows decrease.

Another option for investigating low flow effects on the fountain

darter population is a proposed
fish pass for the Slough Arm of the San Marcos River. The Slough Arm
is
an old channel of the
San Marcos River that was

abandoned decades ago following construction of
a
dam and a

subsequent

large flood that altered the ro
ute of the river
. Water can be diverted to the Slough
Arm through an old mill race that has its head adjacent to the San Marcos River Pub. A fish pass
has been proposed to allow fish movement around the Rio Vista Dam.
It is possible that a
project could

be

design
ed

to
investigat
e

low flow effects on fountain darters and/or Texas
w
ild
-

r
ice, a species that cannot be researched at Comal Springs. While the flood and security
concerns with this location are similar, if not greater, than those with the Old Channel, the cost
would likely be less, the overall project
would restore

rather than
alter
natural habitat
, and Texas
w
ild
-
r
ice
could
be included in future research.

The effects

of low flows

on gill parasites could be studied through a combination of field studies
and laboratory experiments.
Ongoing studies of

gill parasite densities
in the water column in
relation to snail removal
and

the degree of infection of fountain darters should be continued
.

I
nformation
from these field studies
can be bolstered by laboratory experiments that provide
statistically significant information on the
effects of gill parasites on fountain darters under
varying water quality conditions.



Page 85 identifies
intangibles
that may impede the ability to move forward with a given
alternative and cites
reluctance of TPWD staff to support
using the propos
ed
experimental
channels
for conducting research
.
Another intangible cited is the opposition of TPWD to using
the Old Channel for endangered species habitat.

TPWD is indeed reluctant to support the
experimental channels

as well as
many aspects of the
proposed Old Channel ERPA

as currently
proposed, for reasons outlined in these comments
.


TPWD agrees with the recommendation

in the report

that an EARIP ERPA subcommittee or
some form of third
-
party independent review team be assembled to oversee the ER
PA
implementation

and studies conducted during the adaptive management phase of the HCP.
Given
the
current
lack of knowledge regarding many of the listed species and the uncertainties
of biotic
community response to

future
low flow

events
,

i
t seems as thou
gh a series of experiments and
studies formulated by an ERPA workgroup would be more

beneficial
and possibly

more

cost
effective

than research using the proposed experimental channels
immediately adjacent to the
Old Channel
as currently
designed
.

Implementation of any of the ERPA components will require
extensive permitting and funding.


It is likely that if any of the ERPA components are
implemented, they will be in a modified form following interdisciplinary studies related to
habitat, hydrology,

the species of concern, and ERPA design and operation. Creation of the
recommended subcommittee should occur as soon as practical.




Environmental Restoration and Protection Areas

Feasibility Study:
San Marcos

Springs

Several terms need to be quantifi
ed and/or defined. Flows variously described as “low”, “high”,
“average”, “extreme”, etc. need to have numbers or ranges of numbers if at all possible. The
draft HCP has defined the period of the drought of record and the frequency of such an event
fairly
well.
It
should be made clear that these droughts are natural climatic events, not

human

-
induced
events
.

The proposed ERPA in the eastern spillway below Spring Lake is somewhat problematic for
Texas wild
-
rice. Not only is uncontrolled recreation a current problem, but the stands in this
location were either seeded or planted. Thus, genetic diversity within th
is area is probably
limited and this area would not be the best choice for a Texas wild
-
rice ERPA.

There are quite a few assumptions regarding the ability of Texas wild
-
rice to be restored and re
-
established. Most are based on the increase in coverage fro
m 1989 to present. While Texas wild
-
rice has dramatically increased in coverage in the uppermost segments of the river (above Rio
Vista Dam), it has dramatically decreased in coverage below Rio Vista Dam. Because the
reasons for both the increase and decre
ase are unknown, it seems premature to assume that Texas
wild
-
rice can easily recover. Also, flows from 1989 to present have rarely been below 80 cfs and
have mostly been above 100 cfs or even 140 cfs. Thus, to compare the 20 year increase in cover
during
a period of average and above average flows to a period when flows would be at
historical lows for months with brief pulses that would only approach the occasional low flows
does not seem analogous.

There are no documented studies of successful (i.e., inc
reasing in coverage and sexually
reproducing) long
-
term Texas wild
-
rice reintroductions. Several small stands planted by Paula
Power in the 1990s are still extant but have not increased in coverage and do not sexually
reproduce. Again it seems early to ass
ume that it will be easy to increase the coverage of Texas
wild
-
rice through removal of non
-
natives and replacement with Texas wild
-
rice. A new
reintroduction study has been initiated by Mara Alexander (USFWS
-
San Marcos) and Baylor
University that will hop
efully provide more and better data.

I
t is interesting that based on the locations of Texas wild
-
rice in 2009, 1500 m
2

would be in areas
identified as optimal habitat
at a modeled flow of
45 cfs
. A
lthough it is the best estimate
available

as to which stan
ds might be viable during a drought of record, there are many other
variables that could affect the locations of stands. Even though stands do exist in suboptimal
areas, it is not possible with the data supplied to determine which of the suboptimal stands
might
be lost. However, a quick check of the depth would reveal which stands would be in water too
shallow (less than 6 inches) for Texas wild
-
rice to persist. As no plan for recreational control has
been developed or approved, it is difficult to assess wh
ether suboptimal or even optimal stands of
Texas wild
-
rice will be protected during a drought of record. Thus, it is entirely speculative and
unsubstantiated to state that over 2000 m
2
would survive a drought of record.

Although the San Marcos ERPA is onl
y minimally developed, there is such a strong case made
in the report for Texas wild
-
rice being able to withstand a drought of record

that costs, both
monetary and political, of restoring Texas wild
-
rice and controlling recreation should be
provided.

TPWD

staff
do not agree that Texas wild
-
rice would be at moderate risk from the EARIP
proposed flow regime

but rather that the
risk would be high or severe according to
the stated
definitions

Anything lower than the proposed flow regime (i.e., 30 cfs) would be

detrimental.


Literature Cited

Hardy, T.B. DRAFT 2011. Evaluation of the Proposed Edwards Aquifer Recovery

Implementation Program Drought of Record Minimum Flow Regimes in the

Comal and San Marcos River Systems. River Systems Institute, Texas State

University. 80 pp + electronic appendices.

LBG
-
Guyton Associates.


2004.


Evaluation of augmentation methodologies in support of in
-
situ
refugia at Comal and San Marcos Springs, Texas.


Prepared for the Edwards Aquifer Authority,
San Antonio, Texas.