COMMISSION

Permit (ITP) and associated Mitigated Negative Declaration environmental document in the
event the lizard is listed as endangered. The ITP will allow Ocotillo Wells SVRA to continue
with park operations, resource protection, and visitor services that may have the potential to
“take” the lizard.
Invasive Species Abatement Program
Tamarisk (Tamarix spp.) is a non-native species of tree or large shrub that is considered
extremely invasive and found in increasing numbers throughout the arid southwest. Ocotillo
Wells SVRA has high densities of tamarisk
within several of its eastern washes. Through
a cooperative effort with State Park’s
Southern Service Center, the SVRA engaged
in a three-year capital outlay contract to
manage and eradicate tamarisk.
In 2011, a private contractor was awarded
a contract to begin treatment of tamarisk
infestation areas. Methods for removing
tamarisk included the use of various
broadcast foliar herbicides in conjunction
Tamarisk tree
with some physical/mechanical (cut-stump) removal. Ocotillo Wells SVRA GIS staff created
a database that allows SVRA staff to document tamarisk locations, prioritize infestations
for treatment, and track tamarisk response to herbicide applications. Tamarisk infestations
were treated and monitored every year for three years.
The project area consisted of approximately 2,813 acres in which 630 locations were
identified as having tamarisk present. Following the first years application, 93 percent of
areas treated with the herbicide imazapyr showed a favorable response. As of 2013, all
known occurrences had been treated with the outlined eradication methods.
After the conclusion of the contract, since 2013, no chemical treatment has been re-applied
to the major remaining tamarisk stands, and mechanical/physical removal of new growth/
saplings has been the major treatment method. Resource crews continue to survey
for tamarisk in previous and new locations to determine the effectiveness of treatment
methods, look for regrowth, and update the status of infection areas.
While the physical/mechanical methods proved to be most effective at deterring local longterm
regrowth of target stands, both methods have been successful. The remaining invaded
area has been reduced down to approximately 200-250 acres of infested riparian corridor
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California State Parks, Off-Highway Motor Vehicle Recreation Commission