A Fish Habitat Permit for water withdrawal will include requirements to minimize impacts to fish and their habitats. These may include but are not limited to:
- Water intakes must be screened to avoid injury to fish.
Typically screen openings may not exceed 0.25 inches (0.10 inches or less in areas with sensitive fish species or life stages), and water velocity at the screen/water interface may not exceed 0.5 feet per second when the pump is operating.
Quick Tip: To test whether you are meeting the velocity requirement, hold a plastic bag next to the screen intake and the bag should not get sucked up against the screen.
- Pump intake screens should be periodically checked during operations to ensure that the screening has not collapsed, there are no breaks/gaps in the mesh, and the screen has not become blocked by debris.
One simple method to screen a 30-gallon-per-minute or less pump for use in a fish stream is to drill 3/32-inch holes throughout a sealed five-gallon bucket and then center the intake inside this bucket. For larger pumps, screens may be constructed from perforated plate or wedge wire/profile bar.
The Habitat Section Technical Report No. 97-8 (PDF 2,558 kB) contains additional information on screening criteria for various species and life stages of fish as well as methods for design and fabrication of cylindrical water intakes.