How it works

WHAT IT IS: THE FARMERS SCREEN is a horizontal fish and debris screen that has no moving parts and is self-cleaning under normal operating conditions. The Farmers Screen was developed through a decade of trial and error and research and development by farmers, irrigation district employees, engineers, and many others.

The Farmers Screen has been installed in a variety of site conditions and flow ranges. The Farmers Screen has performed well under heavy organic (leaves, sticks, etc.) loads and very heavy silt loads and in diversions with very wide flow ranges. Most current installations have ESA species present, many have multiple ESA species present.

The Farmers Screen meets or exceeds all state and federal agency criteria for fish protection. Three separate studies have been performed on the effectiveness of the Farmers Screen and all three have shown it to be effective for all life stages of anadromous fish.

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HOW IT WORKS: THE FARMERS SCREEN uses the physics of water movement to screen water while safely sweeping fish and debris back to the river or stream. Basically, water enters the screen at a high velocity (4 to 6 feet per second) while water moves very slowly through the screen vertically (0.1 to 0.4 feet per second, after correcting for net open area). These velocities keep the fish and debris moving across the screen while keeping impingement from occurring. There are several components to the Farmers Screen that make it work:

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 Taper Wall: The taper wall decreases the cross-sectional area of the screen as the amount of water decreases. This allows the velocity and depth of the water to remain constant as water is taken through the screen.
 Weir Wall: The weir wall keeps the depth of water over the screen and the draw through the screen constant. The combination of the taper wall and the weir wall keep the velocity across the screen surface high and the velocity through the screen very low.
 Cleaning Water: A percentage of the total flow must be available for cleaning. Quantity of by-pass flow is dependent on screen size, water depth over the screen, and sweeping velocity.
 Screen Material: The Farmers Screen uses a proprietary 50% open area stainless steel screen material.
 Inlet: A proper inlet allows for steady-state uniform flow coming onto the screen. It is important for the water entering the screen to have minimal turbulence.
 Attenuation Bay: The attenuation bay allows the screened water to be collected below the weir wall and moved into the conveyance system (pipe or canal) without affecting the hydraulic function of the screen.
 Fish/Debris Return: The fish/debris return allows water, fish, and debris to sweep off of the end of the screen and into a plunge pool. The design must allow for the water to fall freely off of the screen structure without affecting the hydraulic function of the screen.

THE OPTIONS: THE FARMERS SCREEN is available in two different formats.

 For diversions of 16 CFS and under, the Farmers Screen Modular System is available.
 For larger diversions, the Modular System can be installed in duplicate or a Custom Farmers Screen can be designed to suit the particular site and installed.