Environmental Engineering Reference
In-Depth Information
Box 13.1 Case study: Upper South Platte Watershed Project,
Colorado, United States
The Upper South Platte Watershed Protection and
Restoration Project is implementing restoration actions
at a landscape scale. It is located in the foothills of the
Rocky Mountains near Denver, Colorado (Figure 13.2).
This area is dominated by a mixed ponderosa pine-
Douglas fi r forest. Much of Denver's water supply
comes from this watershed. The South Platte is also
a recreation area, highly regarded for its trout fi shery,
wildlife, and trails. And it is susceptible to severe wild-
fi res that can threaten homes and communities.
The current landscape does not refl ect historic con-
ditions and is not sustainable (Kaufmann
et al
. 2000;
Romme
et al
. 2003). Historically, wildfi re visited this
area every 30-50 years, maintaining a patchy crown
structure in the forests, with small to moderate open-
ings. Fire suppression, logging and livestock grazing
gradually allowed smaller, thin-barked trees to prolifer-
ate. This has resulted in a dense forest and increased
risk of large, high-intensity fi res. The Buffalo Creek
(1996), Hi Meadow (2000) and Hayman (2002) fi res
burned at least 64 280 hectares of forest and 196 built
structures in and around the Upper South Platte.
The Upper South Platte Project was initiated in 1998
to address sedimentation and other issues resulting
from the Buffalo Creek fi re. A primary goal was to
establish more sustainable conditions based on the
historic character of the ecosystem, within the con-
straints of existing human needs. The project was made
possible thanks to an interagency partnership between
the US Forest Service, Colorado State Forest Service,
Denver Water Board and other agencies. These part-
ners adopted watershed restoration as a framework for
overall management and specifi c project planning.
They began with a landscape-scale assessment, com-
pleted in 1999. This assessment helped identify and
prioritize restoration opportunities aimed at maintaining
or restoring important watershed functions.
roads. Where the use of off-road equipment is not
desirable, logs are left on the forest fl oor.
The overall Upper South Platte Project plan is to
treat 13 600 ha over a period of 10 years. Most Upper
South Platte Project treatments consist of tree thin-
nings, with the remainder being small clear-cuts,
ranging from ½ to 6 ha in size. Thinning procedures
are intended to retain larger, more mature trees, par-
ticularly ponderosa pine. Some larger Douglas fi r trees
are removed where they compete with the pine.
Following logging, and a period allowing cut wood
and brush to dry out, treated areas are subsequently
burned. The goal is achieve a fairly open canopy, with
circa 25% canopy cover, which is thought to be the
level that predominated in the historic period taken as
the reference models. In general, managers anticipate
the need for prescribed burns every 10-30 years, in
order to maintain the desired conditions of relatively
open canopy.
Other restoration interventions include:
• Planting riparian areas that have exposed soils.
• Placement of woody debris and boulders in stream
channels.
• Reshaping existing sediment deposits in riparian
zones to facilitate plant re-establishment.
• Re-establishment of ponderosa pine in previously
burned upland areas.
• Selective dredging to remove accumulated
sediments.
• Closure and reclamation of roads.
Altogether about 9600 ha were treated between 1999
and 2010. Long-term stewardship contracts cover a
10-year period. They encourage removing as much
wood as possible to help sustain local businesses.
Between 2012 and 2015, about 2800 ha will be treated.
The Upper South Platte Project plan includes an
adaptive management component, with six areas of
monitoring prescribed:
1.
Threatened, endangered, and sensitive wildlife and
plant species
2.
Forest vegetation and fuels
3.
Noxious weeds
4.
Oil erosion
5.
Water quality
6.
Off-highway vehicle use
Monitoring to date has shown that desired conditions
have been met for fuel ladders, crown cover, tree size
Continued
Restoration approach
Projects on National Forest lands combine thinning,
gap creation, and prescribed fi re to restore a mosaic
pattern that refl ects historic conditions (Plate 13.1).
Open areas and thinned forest serve as fi rebreaks and
buffers around or between remaining areas of dense
forest. Some existing roads are obliterated after use.
Off-road equipment reaches logs not accessible from
