Peacock Creek

Vortex Weir Fishway

Location
Smith River Basin, Northern California. MAP

Project Type
Concrete pool and vortex weir fishway, partially covered by metal arch culvert.

Pre-Project Barrier

  • 7.5 ft (2.3 m) diameter CMP at 4.3% slope with 3 ft (0.9 m) drop at outlet
  • Undersized CMP, overtopped 5-yr flow
  • FishXing identified barriers: depth, velocity, shallow pool, and leap

Channel Characteristics

  • 100-year Flow: 1,250 cfs (56.6 cms)
  • Drainage Area: 2.2 mi2 (6.2 km2)
  • Upstream Channel Width: 18 ft (5.5 m)
  • High Fish Passage Flow for Adults: 79 cfs
  • Total Headloss: 7 ft (2.1 m)

Ecological Value
Provide access to 1.3 mi (2.1 km) of upstream spawning and rearing habitat for coho, chinook, steelhead, and cutthroat trout.

Challenges

  • Two water intakes immediately upstream
  • Highway culvert upstream (not a barrier)
  • Project length limited to 120 ft (37 m)

Project Funding
Del Norte County, CA Dept. of Fish and Game, and CA Coastal Conservancy

Completion Date
November, 2003

Total Project Cost
Approximately $474,000

 


Project Description

The county maintained road at Peacock Creek was labeled a high priority for replacement in the Del Norte County Fish Passage Assessment completed in 2001. Site constraints required maintaining 7 ft (2.1 m) of drop over 120 ft (37 m). A concrete fishway was selected for its overall stability.

Drop over each weir was limited to 8 inches (0.2 m) for juvenile fish passage. To increase the scouring forces and maintain adequate pool depth, a vortex shape was selected. The vortex weirs also had the benefit of providing more weir length for a given head, reducing velocities over the weir, and increasing the fish passage flow range. The weir side slopes were intended to concentrate flows while providing a well defined edge-water for juveniles to leap towards.

Fishway and Weir Dimensions

  TotalLength: 120 ft (37 m) Drop over Weir:
 8 in (0.2 m)
  Total Headloss: 7 ft (2.1 m)
 Weir Side Slope: 5:1 (H:V)
  Fishway Width: 20 ft (6.1 m) Vortex Angle:
 90 degrees
  Pool Spacing: 10 ft (3.0 m)
 Pool Depth: 2.5 ft (0.8 m)