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Antelope Creek Flood Control Project takes a big step forward with completion of Upper Weir

March 07, 2018

After five years of design, permitting and construction efforts, the Placer County Flood Control and Water Conservation District recently completed the first of two planned fish-friendly, on-channel weirs across Antelope Creek in western Placer County. The Antelope Creek Flood Control Project, Upper Weir is part of a regional, multi-objective flood risk reduction solution within the Dry Creek Watershed, and is located along the existing City of Roseville open space corridor and multi-use trail system near the Galleria Mall.

The first weir, or Upper Weir, was completed in early February 2018 at a total cost of approximately $4 million, funded through two grants from the State Department of Water Resources, Proposition 84 Integrated Regional Water Management Program and the DWR Urban Streams Restoration Program. Local funding sources included the use of Dry Creek Watershed mitigation fees collected from new development. The district is currently seeking grant funding opportunities to complete the second planned weir, or Lower Weir.

“The concrete weirs are designed to slow down the flow of Antelope Creek in the event of a major flood, and will also provide as much as 760 cubic feet per second of 100-year peak flow decrease, as measured in downtown Roseville. The project will mitigate as much as 84 percent of the increased peak flows, resulting from all planned future development within the watershed,” said Placer County Flood Control and Water Conservation District Manager, Brian Keating.

The project had to clear an extensive environmental permitting process in order to move into the construction phase, and the District was obligated to mitigate its project impacts both on-site and off-site. The District will be monitoring and maintaining the site for many years to come.

“As one of its member agencies, we are pleased that the Placer County Flood Control District has successfully completed the first phase of the Antelope Creek Detention Basin,” said Brian Walker, Roseville Floodplain Manager. “This regionally significant project is designed to mitigate drainage impacts caused by land development within the Dry Creek drainage basin in Placer County, Rocklin and Roseville."

Environmental benefits that will stem from the project include the removal of existing culverts and a partial fish passage barrier, restoration of native vegetation to the creek corridor and the removal of non-native plants. The project also includes habitat improvements for existing salmon and steelhead trout, such as a downstream rock weir and a plunge pool.

The Upper Weir project completion also brings improved public access along the existing multi-use Antelope Trail, and flood control benefits to critically impacted areas of western Placer County. A realigned and repaved path, security fencing and an interpretive sign along the trail were added to help educate the public.

To see more of the Antelope Creek Flood Control Project photographs, click here.

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