Farmers Screen FAQs
What is the Farmers Screen?
The Farmers Screen is a horizontal fish and debris screen that has no moving parts, requires no power, and is substantially self cleaning.
How does it Work?
The Farmers Screen uses hydraulics to effectively manage debris and protect fish. Water moves over the screen surface at a relatively high velocity and moves through the screen at a relatively low velocity. This combination of a high sweeping velocity and minimal downward (approach) velocity moves fish and debris over the screen and back to the river or stream. An oscillating velocity (water moving up and down through the screen) creates a pulsing action that also contributes to the self-cleaningcharacteristics of the screen.
How is it different from other fish screens?
The Farmers Screen has no moving parts and does not use power, plus the horizontal orientation makes the Farmers Screen distinct. These properties lead to a much reduced operation and maintenance requirement.
Who invented it?
The Farmers Irrigation District staff and district members with input and help from various local, state, and federal agencies.
Is it patented?
Yes, Farmers Irrigation District owns the patent and it is licensed to FCA. The U.S. patent numbers are: 6,524,028, and 6,964,541. The Canadian patent # is: 2,440,140.
Who is FCA?
Farmers Conservation Alliance (FCA) is a nonprofit social enterprise organization responsible for educating the public about the need for fish screens; refining, marketing, and selling the Farmers Screen; and using profits to invest in other solutions that benefit both the environment and agriculture. FCA began in 2006 when the inventors of the Farmers Screen, the Farmers Irrigation District of Hood River, Oregon, licensed the Farmers Screen to FCA with the condition that all profits be invested in to other technologies and solutions that benefit the environment and agriculture.
Does the Farmers Screen meet NOAA/NMFS Criteria?
Yes, the Farmers Screen has specific criteria created and approved by the National Marine Fisheries Service (NMFS). The criteria developed specifically for horizontal fish screens can be found in the “NMFS Anadromous Salmonid Passage Facility Design” document published in July of 2011. The relevant section pertaining to horizontal screens is 22.214.171.124 and can be found beginning on page 90.
Are there different types of Farmers Screens?
Yes, the Farmers Screen comes in both a modular (prefabricated) format for smaller diversions and a custom design for larger diversions. The Farmers Screen can also be designed to handle high sediment loads and wide flow ranges.
Can the Farmers Screen be installed in stream?
No, the Farmers Screen is designed to be installed in an off stream channel only.
How do you control the flow to the system?
The Farmers Screen requires a method of controlling flow upstream of the screen, typically in the form of a head gate.
How much slope does the screen have?
The Farmers Screen does not have a slope to it. It is installed perfectly level.
How much fall or elevation differential is needed for the screen to work?
An elevation differential is necessary in two places: the canal or conveyance and the river or stream. For the conveyance, one foot is preferable; however, it is possible to make it work with as little as 6 inches. If there is a long conveyance prior the screen, then a greater elevation differential may be necessary to induce the proper velocities at the screen. The conveyance differential would be measured from the point of diversion to the distal (downstream) end of the screen. The river or stream also needs to have an elevation differential or fall to accommodate the return of the cleaning water to the river or stream. The river or stream must have a higher gradient than the canal or conveyance. The elevation differential necessary in the river or stream is dependent on the species present and the preference of the biologist working on the project. For projects with anadromous species present, the elevation differential from the screen surface elevation to the point where the cleaning water re-enters the stream must be great enough to meet NMFS guidelines for by-pass hydraulics.
How much space does a typical screen need?
Space requirements are totally dependent on the flow range of the screen. Farmers Screens are long, narrow structures that typically fit nicely in the width of a canal. A wide flow range will typically require a dual screen configuration which will increase the width of the structure. Modular screens up to three sections are 3 feet wide and each modular section is 10 feet long. Modular screens of 4 sections or more are 5 feet wide. All screens will require an entrance flume which is typically at least 6 feet long and increases in length as the screen size increases.
What is the smallest diversion that can be screened with a Farmers Screen?
0.5 CFS is the bottom end of the flow range for the smallest modular Farmers Screen. FCA has installed modular screens that operate at 0.5 CFS.
What is the largest diversion that can be screened with a Farmers Screen?
There is no maximum diversion size that The Farmers Screen can be sized for. To date, the largest diversion screened is 165 CFS.
Does the screen provide safe fish passage?
Yes, the Farmers Screen provides safe and effective downstream passage. If acceptable to agency representatives, the Farmers Screen can provide adult upstream passage. Farmers Screens have been installed to provide upstream passage however it is not typical. FCA has six biological and hydraulic tests demonstrating fish protection. (Available upon request.)
How does the Farmers Screen handle high levels of organic debris?
The Farmers Screen has been installed on systems with very high leaf, woody debris, and fir/pine needle loads and has performed very well through several years of operation with very minimal maintenance requirements. How does the Farmers Screen handle sediment? The Farmers Screen was developed on a high sediment, glacially fed river system. Sediment load must be taken into account during the planning/design phase. When planned for, even very high levels of sediment can be effectively managed with the Farmers Screen. If not planned for, high levels of sediment will cause operational issues and increased levels of maintenance.
How does the Farmers Screen handle larger sediment, sand, angular pebbles, and cobbles?
The Farmers Screen has been installed on systems high in a glacially fed river basin with extremely high levels of sediment, sand, gravel, and cobbles and has performed very well through several irrigation seasons. Proper diversion design is crucial in minimizing the quantity of larger material entering the screen structure. In general, gravel and cobbles along with some sand and suspended sediment move across the screen surface and back to the river or stream. However, it is possible for small, angular gravel to lodge on the screen surface. Routine observation and maintenance is necessary to keep the screen operating optimally.
How much does a Farmers Screen cost?
Modular Farmers Screens start at close to $25,000 and increase to about $80,000 for a 16 CFS Modular Farmers Screen with all available options. For custom screens, the cost is dependent on a variety of factors but will fall within a range of about $5,000 to $9,500 per CFS.
How do I get a Farmers Screen?
Ultimately, the Farmers Screen comes directly from FCA but it can be purchased through an engineering firm, a state screen shop, or any other agency or entity that is coordinating or managing a screening project. The first step is to contact FCA to discuss project particulars to determine if your site is appropriate for a Farmers Screen.
Can an engineering firm use the Farmers Screen technology?
FCA partners with many different engineering firms to provide the Farmers Screen for specific applications. As with other technologies (such as mechanical weirs, gates, and pumps), FCA provides engineering firms with specifications for the proper infrastructure (boundary conditions) to accompany the Farmers Screen. FCA provides the actual screen itself, while an engineering firm designs the accompanying structures and site work.
How long does it take to install a screen?
A modular screen will take from one to two days depending on the size of the screen and the site conditions. A custom screen will take much longer and will depend on other aspects of the project.