Snake River White Sturgeon Conservation Plan ... - Idaho Power

Idaho Power CompanyChapter 4: Conceptual Design for White Sturgeon Passage Facilities4.3.3.2. Biological EffectivenessWe found no biological data for using pressurized fish locks to pass sturgeon downstream.Similarly, we found no information that helped us evaluate the design of a chute. For moreinformation about the biological effectiveness of fish locks and fish lifts, see Sections 4.2.2.2.and 4.2.3.2., respectively.Research is needed to prove the biological safety of a pressurized passage system. The reactionof sturgeon to changes in pressure, particularly when the surrounding water is supersaturatedwith gas, would be of particular interest. The conclusions of such research would help determinethe safe cycle time of a pressurized system. As with a fish lift or fish lock, the entrance and itsattraction methods would largely determine how efficiently any pressurized passage systemcould attract sturgeon.4.3.3.3. CostsBecause it is an untried system, we found no model of costs for a pressurized passage system.Additionally, because this system is experimental, there is significantly greater risk of costoverruns than for conventional methods of passing fish.4.3.4. Behavioral Guidance Structure4.3.4.1. DescriptionA behavioral guidance structure’s only purpose is to direct migrating fish to a specific area.These structures are used to supplement one of the passage systems described previously.A behavioral guidance structure can be constructed of steel or other materials and placed alongthe dam face or in the river channel itself to direct fish to bypass systems.A behavioral guidance structure is located at the lock at Lower Granite Dam on the Snake River.It was placed along a trash shear boom that is relatively shallow, causing juvenile salmonid fishnear the surface to travel along the trash boom. Based on their experience with the trash boom atLower Granite Dam, the U.S. Army Corps of Engineers constructed and are testing a behavioralguidance structure that extends substantially deeper into the water (Figure 22). Although it wasnot intended to, the surface collection channel placed at Wanapum Dam has acted as a behavioralguidance structure by directing fish to the spillway and increasing the efficiency of the screensystem for the turbine intake. At Lower Granite Dam, the performance of screens for the turbineintake has also been improved by the addition of the surface collector and other associatedstructures.Both of these behavioral guidance structures are designed to guide juvenile salmon andsupplement the actual collection and passage system, regardless of the type of system. Otherexamples of behavioral guidance structures include use of light, sound, electrical stimuli, and airbubble curtains to discourage fish from entering turbine intakes.A behavioral guidance structure for sturgeon would have to differ from the systems describedpreviously because sturgeon are bottom dwellers. Therefore, for a surface passage system, thebehavioral guidance structure could take the form of a ramp that would guide the fish from depthHells Canyon Complex Page 29