Fish Barrier Design Evolution in Montana

1. Fish Barrier Design Evolution in Montana George Austiguy PE, Pioneer Technical Services With Contributions by Dale White PE, USFS

2. Fish Barrier Design Evolution in Montana • Early barrier designs were based on the concept of a height barrier. • So… How high can a fish jump? Let’s try 4 ft. • Limited data on how high a salmonid could jump => Barrier designs became based on theoretical leap estimates as a function of fish burst speed.

3. Fish Barrier Design Evolution in Montana

4. Fish Barrier Design Evolution in Montana How fast can a fish swim? => Data old, based on laboratory measurements, not representative of field conditions = uncertainty

5. Fish Barrier Design Evolution in Montana • This height based design approach led to fish barrier designs with an downstream apron on-grade with a weir crest 4 – 5 ft above the downstream design flow (typically Q50 in MT.) water surface elevation

6. Fish Barrier Design Evolution in Montana • Breeching of height based designed fish barrier structures for which conservative, theoretical fish leaping calculations predicted were not breachable (i.e. the fish could not leap over) led to a focus on the downstream conditions. i.e. what’s wrong with our model? • Analysis of the breached structures indicate downstream aprons had variable hydraulic conditions which potentially fish were able to exploit and use to breach the barrier.

7. Fish Barrier Design Evolution in Montana Temporary Apron On-Grade Fish Barrier Cherry Creek, MT Breached by Rainbow Trout. Weir Height = 4.5 ft.

8. Fish Barrier Design Evolution in Montana • These variable hydraulic conditions can include clinging nappes, eddys and standing waves, and micro low-energy streams associated with turbulent flow caused by non-uniform downstream geometry; • The ability of salmonids to exploit small variations in energy within the flow stream to pass obstructions is supported by research using PIT tagged fish and 3-dimensional modeling (M.Blank, 2005“Studies of Fish Passage Through Culverts in Montana”);

9. Fish Barrier Design Evolution in Montana • Research on brook trout (Kondratieff and Myrick, 2006, “How High Can Brook Trout Jump”)indicates that leaping ability by brook trout is a direct function of the water depth in the downstream region of the barrier; • Tools available to design practitioners are typically limited to simple, 1-dimensional hydraulic models (HEC-RAS);

10. Fish Barrier Design Evolution in Montana • Collectively these observations and research results pushed our fish barrier design concepts to focus on producing downstream hydraulically uniform, 1-dimensional flow conditions, with shallow depth and high velocities to eliminate the ability of fish to leap in the first place; • If the flow depth is too shallow for a fish to orientate to a leaping angle, it cannot jump; • Apron flow that is supercritical (shallow and fast) uniform flow, requires a fish to constantly be in burst mode, eliminates locations where a fish could rest or leap from. • Wing walls adjacent to the downstream apron: • Provide geometry that produces uniform flow conditions; • Produces 1-dimensional dominated uniform flow conditions=> allows 1- dimensional hydraulic modeling better predictive performance • Elevated apron crest maintains supercritical apron flow; • This design concept is consistent with fish barrier design guidelines adopted by NOAA Fisheries (BOR, 2006, Fish Protection at Water Diversions)

11. Fish Barrier Design Evolution in Montana The specific structure design criteria used : • The downstream crest of the apron will be elevated 1 ft above the maximum design tailwater elevation; • The minimum apron length will be 16 feet; • The minimum apron slope will be 16H:1V; • The minimum weir height of the barrier will be 3.5 ft above the apron height; and • The structure shall be designed to exclude fish passage up to the 50-year flow and to structurally withstand the 100-year flow.

12. Fish Barrier Design Evolution in Montana Hydraulic Modeling Example of Elevated Apron Courtesy of Dale White USFS

13. Fish Barrier Design Evolution in Montana Hydraulic Modeling Example of On-Grade Apron Courtesy of Dale White USFS

14. Fish Barrier Design Evolution in Montana • Recent examples of this design concept are shown on the following slides

15. Fish Barrier Design Evolution in Montana Temporary Fish Barrier, Casias Creek New Mexico

16. Fish Barrier Design Evolution in Montana Smith Creek Fish Barrier Montana

17. Fish Barrier Design Evolution in Montana Cherry Creek Fish Barrier, Montana

18. Fish Barrier Design Evolution in Montana Greenhorn Creek Fish Barrier, Montana

19. Fish Barrier Design Evolution in Montana Muskrat Creek Fish Barrier, Montana Courtesy of Dale White USFS

20. Fish Barrier Design Evolution in Montana NF Highwood Creek Fish Barrier, Montana