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Siting Criteria

The considerations shown below are intended to guide initial site assessment. Local fish passage regulations and the specific nature of the host stream will guide a final screen design, along with other site-specific requirements.

  • The proposed site must be located off-channel and flow to the screen controlled with a properly functioning head gate.
  • There must be sufficient flow entering the screen to ensure 5 to 10% of the diversion is returned to stream as bypass flow.
  • Water at the leading edge of screen must be steadily and uniformly flowing at 1 to 2 meters per second. A straight flume five times longer than the width of the screen’s leading edge will generally create this even flow.
  • A drop in water surface elevation of 15 to 30 centimeters is needed between the flume and the exit of the screened flow.
  • The host stream must not back up the fish return.
  • The screen area can be estimated as 20 square meters for every cubic meters per second of flow. The footprint of the structure is typically twice that. The length to width ratio of this footprint varies significantly.