Loma Rica Reservoir Cleaning Project

The Loma Rica Reservoir is located directly east of the City of Grass Valley, Nevada County, California, at an elevation of 3,154 feet above mean sea level (msl).  The reservoir is located on property owned by the Nevada Irrigation District (NID) and it is approximately 1,500 feet east of the Nevada County operated airport and public use runway.  The reservoir is part of the NID water-supply system and it stores raw water delivered through the Cascade Canal and the Banner Cascade Pipeline. The reservoir had a maximum capacity of 96.9 acre-feet (31.6 million gallons) when it was first constructed in the early 1960’s.  Since then silt and sediment deposited in the reservoir with the incoming water sources have significantly decreased its capacity. This decrease adversely effects capacity of NID’s drinking and irrigation water systems.    

Water from the Loma Rica Reservoir supplies the Loma Rica Water Treatment Plant and the Chicago Park Canal, an NID supply route for raw-water customers. The reservoir is not directly connected with any local creeks nor does it discharge to any natural water bodies or streams.

The Loma Rica Reservoir Cleaning Project proposes to dredge the Loma Rica Reservoir, which would involve removing accumulate sediments and materials.  This would restore the reservoir’s original capacity of just under 100 acre-feet.  An estimated 40,000–70,000 cubic yards of sediment would be removed over a period of four to six months.  The project may also entail including the installation of a chain-link fence around the perimeter of the reservoir in order to minimize the access of the NID’s facility to the public.

The removal of the sediment will be accomplished by first draining the reservoir. The sediment would then be excavated using front-end loaders, excavators, drag-lines, suction dredges, dump trucks and/or other suitable equipment.  The excavated sediment would be placed on adjacent previously disturbed land in order to drain the sediment of remaining water and to allow for drying. The sediment would then be transported off site to be recycled as fill material, if determined to be suitable for that purpose. 

The Reservoir cleaning will occur between September 15 to March 15.  This time frame will minimize environmental impacts and take advantage of lower water demands for the NID such that the reservoir inactivity will not significantly affect NID’s operation.

The identified potentially significant impacts of the project will be less than significant with the incorporation of mitigation measures into the project.  The potentially significant project impacts and associated mitigation measures are included in the project’s Initial Study/Limited Negative Declaration dated April 5, 2013 and posted on this website page under “Project Documents”.    A hard copy of this document can also be reviewed at the NID’s office in Grass Valley, at the Madelyn Helling Library in Nevada City at 980 Helling Way, or at the Nevada County recorders office.

The adoption of this project occurred at the NID public Board Meeting on May 22, 2013.

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