CC Waterfall Fire Watershed Assessment, Recommendations, Design & Implementation

Project area showing extent of
the Waterfall Fire and
the affected drainages.

View of a large head-cut in
the Slide Canyon headwaters area
west of Carson City.

View of flooding and sediment
in neighborhoods January 2006

Carson City Parks & Recreation Department/Waterfall Fire Watershed Assessment, Recommendations, Design and Implementation

Resource Concepts, Inc. (RCI) conducted an assessment of the 20 square mile watershed on the west side of Carson City and developed recommendations and designs for long-term restoration of highly degraded areas. The purpose of the project was to develop long-term restoration solutions for the portions of the watershed that burned in the 2004 Waterfall Fire. Although emergency measures were installed immediately following the fire, design and implementation of long-term restoration was needed as evidenced by excessive sediment coming from the watershed. Two years following the fire, above-normal precipitation events resulted in tons of sediment and ash flowing into the City. The watershed is also an important deer winter range.

The assessment was conducted on foot and via helicopter. Over the course of eight months, RCI’s interdisciplinary team photographed, mapped and described the state of the watershed. The information was graphically captured and combined with geology, soils, topography, slope, vegetation and hydrology information. The team discovered that the watershed was very unstable primarily due to extremely steep slopes, highly erodible soils, faults, and past human activities. The information was presented to stakeholders including congressional delegations as part of City’s effort to obtain funding for implementation.

The RCI watershed team developed 39 project recommendations to address areas of concern in the watershed. The recommended projects were prioritized using a point system based on the threats addressed and the benefits to be achieved by each project. The recommendations focused on water quality, drainage, flooding, sediment yield and controls, revegetation, watershed stability, habitat, and public safety.

RCI’s interdisciplinary watershed team consisted of professionals with expertise in fluvial geomorphology, geology, hydrology, revegetation, wildlife, soils, forestry, range management, GIS and civil engineering. This is the same team proposed for the NDOW Riparian Restoration projects. The team collaborated with the Nevada Division of Forestry, the US Forest Service, National Resource Conservation Service (NRCS), Carson City Public Utilities, Carson City Open Space, and private landowners. Past, present, and future activities in the watershed relating to watershed health and stability were considered.

Following the assessment, RCI was retained to complete designs for several of the highest priority recommendations. The designs involved floodplain and riparian area enhancement on the alluvial fan areas. The projects will essentially restore the connectivity of the drainageways to their floodplains. As a result, the habitat, species diversity, and ecosystem function of the alluvial fan areas will be somewhat restored within the confines of property boundaries and water rights conveyance requirements. The designs are scheduled for implementation during the summer and fall of 2008 using funds from the NRCS.