A
Vision For Riparian Protection
Riparian areas in a desert environment are
vital places. Although sixty to seventy-five percent of all
species in Arizona rely on a riparian environment at some point
during their life cycle, a number of streams and springs in
and near Tucson have ceased to flow year round or are affected
by a lower water table. Our streams and springs need protection
as well as restoration.
Riparian Protection
Riparian resources and aquatic
systems are the most vulnerable and least protected habitats
in Pima County.
Two years of review and research during the Sonoran
Desert Conservation Plan process have added greatly to Pima
County,
Arizona’s understanding of its riparian resources. In
addition, previously unknown perennial and intermittent streams
and springs have been identified.
Threats to Riparian Systems
It is now known that there are more threats to riparian systems
than the obvious ones. The impact is evident when a housing
development destroys a creek or stream environment. However,
the decline in groundwater from pumping or the spread of invasive
non-native species may be less obvious, but may actually destroy
as much or more riparian habitat.
Making Up for Lost Ground
While it is far too late to restore many of our riparian communities
to their natural condition, the Sonoran Desert Conservation
Plan proposes that other natural riparian systems be preserved,
restored, and managed to compensate for decades of largely
unintended destruction of these systems.
Protection Yields Benefits
The Sonoran Desert Conservation Plan validates Pima County’s
previous investments in protecting riparian areas such as Cienega
Creek, Tanque Verde Wash, the San Pedro River, and Sabino-Bear
Canyon. The Plan has identified additional areas for protection.
This action will not only protect wildlife and plants, but
will also maintain recreational trails, promote groundwater
recharge, protect water quality, and attenuate flooding.
High Impact to Urban Streams
Low elevation, valley-floor streams in eastern Pima County
have been disproportionately affected by loss of water, loss
of native species, and other problems. Today we have the opportunity
to recreate some urban riparian systems using renewable sources
of water which will in turn provide urban revitalization, recreation,
and park development. The most benefit to the urban area will
result from repairing the degraded riparian environments of
our major drainage systems – the Santa Cruz, Rillito,
and Pantano rivers and washes – and by enhancing protection
of the remaining riparian fragments along their tributaries.
The Science and Technical Advisory Team adopted specific ecosystem
function goals for the management and conservation of riparian
areas. Major watersheds were identified and used as planning
units. To the extent possible, the connection should be maintained
or restored between interdependent components of river systems
within a watershed such as the channel, overbank, floodplain,
distributary flow zones, riparian vegetation, and connected
shallow groundwater.
The appropriate management of uplands within each watershed
will protect the dynamics of riparian and aquatic ecosystems.
Sources of pollution that impact our river systems must be
identified and managed to maintain water quality at a level
that will meet the biological goals of the Sonoran Desert Conservation
Plan. Sufficient in-stream flows must be ensured to achieve
and protect the natural functions of riparian and aquatic ecosystems.
Priorities
for Protection
The Science and Technical Advisory Team also established priorities
for determining which areas should be protected. Protecting
self-sustaining riparian and aquatic ecosystems that already
exist is preferable to the creation of new or enhanced areas
of riparian and aquatic life that depend on continual artificial
inputs of water, energy, and materials. Priority is placed
on the substitution of renewable water supplies for groundwater
and surface water in areas where high-quality aquatic and riparian
ecosystems still exist and where the diversion of water stresses
those systems.
Priority Resources
The selected Priority Riparian Resources include:
•
Rincon Creek, Cienega Creek, Arivaca Creek, Brown Canyon, Wakefield,
Sutherland, Happy Valley, and portions of the San Pedro River
which offer the greatest potential to protect valuable riparian
habitat adjacent to existing natural preserves.
•
Opportunities to add new riparian acquisitions to a larger
landscape with existing uplands exist along Davidson Canyon,
Gardner Canyon, Madera Canyon, Agua Verde Wash, and Sopori/Papalote
Wash.
•
Sonoran cottonwood-willow forests should be protected, 37 percent
of which are located outside existing natural preserves.
Several restoration projects have been completed and more are
in the process of being planned. Riparian restoration feasibility
studies currently underway include:
•
Rio Antiguo Restoration in conjunction with the Army Corps
of Engineers.
•
Paseo de las Iglesias in conjunction with the City of Tucson
and the Army Corps of Engineers
•
Tres Rios del Norte in conjunction with the Town of Marana
and the City of Tucson.
Evaluation Process
Many peer-reviewed studies were used to identify and evaluate
the condition of, threats to, and opportunities for preserving
and restoring riparian ecosystems in Pima County. Pima County
staff and other experts mapped riparian areas outside the Tohono
O’odham Nation and evaluated the availability of natural
surface and groundwater supplies that sustain them.
“
Gap analysis” revealed that some of the largest and most
important riparian areas lie outside existing reserves. Studies
of existing reserves have shown us that land protection does
not address issues such as groundwater depletion and habitat
loss due to non-native species.
Studies prepared for the Sonoran Desert Conservation Plan indicated
that many of our urban waterways are still quite wild and closely
linked to the mountain canyon “refugia” for native
aquatic animals. Urban development and restoration efforts,
therefore, must include considering the impacts and benefits
to native plants and animals and the ecological processes that
sustain them.
Conservation Stategies
The Pima County Comprehensive Land Use Plan was developed
in concert with the Sonoran Desert Conservation Plan. It
includes
guidelines to conserve 95 percent of the riparian areas that
will be affected by development.
Pima County will integrate water and land use planning in
order to protect and restore riparian areas. Land and water
rights
acquisition and partnerships with other government and private
entities will also be used.
Conservation easements, zoning revisions, species re-establishment,
control measures for non-native species, and riparian restoration
are other strategies that have been or will be implemented
to effectively protect riparian areas.
Water must be made available to riparian areas that are to
be restored. An agreement with the City of Tucson permanently
secures a minimum of 5,000 acre-feet of treated effluent
per year for riparian restoration. The amount will rise to
10,000
acre-feet in 2005 and successive years.
Other sources of water are being considered and include treated
effluent from Pima County wastewater facilities, stormwater
runoff harvested from project sites, water rights acquired
from previous uses such as agriculture and mining, and water
from groundwater remediation projects.
Riparian Resources
Map (PDF)
Riparian Protection
and Restoration Element:
Adopted Goal Statements
La Corua - A Sonoran Tradition
Sonoran Desert Conservation Plan
Pima County Administrator’s Office
130 West Congress, 10th Floor
Tucson, AZ 85701
520-724-6460
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