Screen for 4-inch pump rated @ 750 gpm |
These activities require a Fish Habitat Permit.
Water withdrawals include any operation in which water is pumped from a stream. Several examples include using water to maintain vegetation, build ice roads, or if water is pumped from a stream during a diversion/dewatering operation. Water withdrawals can be a risk to fish, especially juveniles, if the pump intake has enough velocity to suck fish in, or if site is unintentionally dewatered. A Division of Habitat Fish Habitat Permit for water withdrawal carries screening stipulations for the pump intake. These conditions dictate maximum mesh opening sizes for the screens to prevent fish from entering the pump and a maximum approach velocity for water at the screen’s surface to prevent fish from being entrained or impinged on the screen. The intake screen mesh size and dimensions are influenced by the different swimming abilities of various species and age classes of fish present at the water withdrawal site and the pump rate. One simple method to screen a 300-gallon-per-minute or less pump for use in an anadromous 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 wedgewire/profile bar (example). Please contact the Habitat office closest to your project site for assistance in determining the appropriate screen criteria for your project. If your project occurs in a fish bearing waterbody, the following stipulations (or other stipulations necessary to protect fish habitat) may be written into your permit:
Most water withdrawals will require a water use permit from the DNR Division of Mining, Land and Water. Additional permits, authorizations or reviews may be needed from the U.S. Environmental Protection Agency or the Alaska Department of Environmental Conservation if the water is being discharged into a water body after use. |
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