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public and private, for each of these
projects. SWT then set out to secure
funding. The results were impressive:
$775 from the Syntal Corporation;
$1,000 from the San Marcos River
Foundation; $1,000 from the
MarshMALLOW Program; $1,150
from Texas A&M University’s Adopta-Wetlands
Program; $2,500 from the
USNPS’s RTCA program; $5,000 from
the National Fish and Wildlife Foundation;
$10,000 from SWT’s Merrick
Funds; $17,000 from private donors;
and $19,000 from U.S. Fish and Wildlife
Service’s Partners for Wildlife Program.
And in March 1998 the biggest
grant of all, $500,000, was given by
the Meadows Foundation of Texas.
Then in partnership with Texas Parks
and Wildlife Department, an additional
$130,000 was obtained for riparian
exotic tree removal (e.g.,
Chinese tallow), native plant acquisition
and education/interpretation development.
With funding secured, the
WPT began to form partnerships
around the demonstration projects.
Americorps offered cost-effective labor
for plant removal, boardwalk construction,
and trail construction. Hays
County Master Gardeners offered
landscape design for the demonstration
pond. Private donors offered
boardwalk design assistance and plant
and material donations.
The Vision
Aquarena is a tremendous resource,
however the physical and biological
character of the habitat has been dramatically
modified by humans. Historical
records indicate a dramatic
change in plant and animal communities
in Spring Lake and the slough
during the past 65 years. In particular,
a large number of plant and animal
species were introduced, and
today about 25% of species in Spring
Lake are exotic.
Removal efforts have been a success; presently the
slough is 99% free of water hyacinth.
Animal species (nutria, swan, geese,
and giant rams-horn snails) introduced
into Spring Lake increased in abundance
due to domestication and ability
to adapt to disturbances. These introduced
herbivores may significantly reduce
stands of Texas wild rice and other
native plants (USFWS 1996).
The slough area of Spring Lake was
historically vegetated with cattails and
other emergent tall grasses that provided
habitat and forage for native
wildlife. Today, most shoreline areas
of the San Marcos River have been
taken over by Colocasia esculenta (taro
or elephant ears), a plant native to India
and southern Asia. The plant tolerates
bright sun to deep shade, readily
reproduces vegetatively, and exhibits
allelopathic properties (Wang 1983)—
characteristics that enable it to be
highly invasive. Consequently, diver-
sity of native species in littoral zones
of the river has diminished. Elephant
ears are also thought to decrease habitat
suitability for the San Marcos gambusia,
thus contributing to its decline
(USFWS 1996). Another effect of elephant
ears on the San Marcos River
ecosystem is their impact on water
quantity. The broad-leaved morphology
of the plant suggests it is a high
water user. As much as 17,500 acrefeet
of water are lost annually in the
upper five-mile section of the San
Marcos River through elephant ear
evapotranspiration.
The first step in restoration of the
wetlands is removal of exotic species.
Removal of exotic animal species
is accomplished by baiting and
trapping methods. Removal of exotic
plant species has been ongoing
for the past two years. Open areas
The San Marcos River, one of the world’s clearest rivers, arises on the campus of Southwest Texas State University. Photo
by Thomas Arsuffi.
International Journal of Wilderness DECEMBER 2000 • VOLUME 6, NUMBER 3 19