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Spruce Wash Flood Projects Continue 

City-County-US Forest Service Work Together to Increase Channel Capacity 

Post Date: 10/29/21

The Stormwater Section completed one in a series of projects to mitigate Museum Fire flooding with a channel and floodplain expansion at the top of Paradise Road, where Spruce Wash enters the eastside neighborhoods. This joint project with Coconino County and Coconino National Forest addresses the potential of increased flows resulting from the Museum Fire scar at the jurisdictional interchange

Channel improvements were based on flood flow modeling of a 2” rainfall in one hour yielding 1329 cubic feet per second (cfs). This channel was designed to maximum capacity in the footprint available of up to 1460 cfs, when modeling indicated flows could overtop the barriers.

The channel was widened, and bollards were installed to bolster the concrete barriers, then backfilled to create a berm for stability, covered by erosion-control matting. Rock alignments were constructed in the channel to direct flows to the center of the channel and reduce erosion. 

Water Services is in the design phase to deliver additional channel and road crossing improvements in the Museum Fire watershed, along with drainage improvements for the East Flagstaff-Dry Lake Hills watersheds. Stay tuned!

Questions or comments? Reply to Flagwater@flagstaffaz.gov or call (928) 213-2471

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