Columbia River Basin Fish Screen Programs
Funding for Construction and Maintenance through the Council’s Fish and Wildlife Program
Rotary Drum Screens
Paddle Wheel-Driven
A common screen type that uses water current to rotate the drum to clear debris and maintain effective screen operation. The site must have sufficient water current to turn the paddle wheel and a consistent water depth to appropriately size and place the drum screen. Shallow water levels at the screen will prevent it from cleaning properly and if water depth increases above the screen design, fish may get over the screen and lost down the ditch. Because this screen type passes debris over the screen and down the diversion ditch, it is not preferred for municipal water diversions or sites that feed sprinklers due to the presence of debris in the source water.
Solar Powered
For this screen type, solar power rotates the drum to clear debris and maintain effective operation. Appropriate screen submergence is necessary for the drum to clear debris without allowing fish over the drum. Since this screen type will pass debris over the screen and down the diversion ditch, it is not ideal for municipal water diversions or sites that supply sprinklers. This screen type is generally utilized in areas that are appropriate for a rotary drum screen but do not have enough current to drive a paddle wheel cleaning mechanism.
Photo: Washington Department of Fish and Wildlife
Vertical Traveling Belt
Traveling belt screens are effective for sites with a wide range of water depths during the period of use. This screen is not as sensitive to water depths as the rotary drum screen. Although traveling belt screens usually pass debris down a diversion canal, they can be modified to collect debris on the back side of the screen and reduce the amount of material in the water delivered to the place of use.
Vertical Panel
Vertical panel screens direct debris and fish towards the bypass and back into the source stream. Water is diverted to the user without the debris load present in systems that use a rotary drum or traveling belt screen. Municipal and sprinkler irrigation operations benefit from the reduced debris load that is provided by a vertical panel screen. These screens usually have one or more wiper brushes that travel along the screen to remove debris which maintains maximum fish protection and water delivery to the user.
Horizontal
The horizontal screen operates with no moving parts and is substantially self-cleaning, typically resulting in less maintenance. Water flows over the screen surface allowing fish and debris to pass quickly over the screen and back to the river or stream, while a portion of the water moves slowly through the screen. This screen works well in high sediment and high gradient systems, but does require at least one foot of elevation differential and adequate by-pass flow. This patented screen technology is available through the Farmers Conservation Alliance .
Brushed Cone
Cone screens are ideal for shallow water intake scenarios where they are permanently submerged below the surface with external brushes that facilitate a self-cleaning function. The external brush-cleaning action prevents the build-up of materials that could foul the equipment.
Water passes through the wire screen, then through the base structure, and into the intake system. The cone-shaped design delivers minimal head loss through the screen to ensure efficient water delivery.