The Jacobs Lower Island Ditch Diversion Replacement (Jacobs Lower Island) project was initiated to replace two perched log and rock push-up irrigation dams with two lay-flat diversions. The perched alluvial fish passage becomes active during irrigation season when the temporary check sills are put in place. The alluvial fish passage channels of the new structures are designed to meet current fish passage criteria for all life stages under all flow conditions. Fish passage is the foundation of population recovery, which is the reason our restoration efforts focus on restoring stream-simulated passage at all crossings and diversions. The project is located in the upper mainstem John Day River in critical habitat waters that exhibit salmon and steelhead spawning, migration, and juvenile rearing.
Before Construction: Jacobs Lower Island Diversion Project in 2011. Note lack of fish passage due to tall waterfall.
Additionally, Tribal staff planted all the disturbed areas of the Jacobs Lower Island project area in September of 2015, as riparian improvements are essential for channel complexity and providing quality habitat for species recovery. Long-term protection of riparian and wetland sites is a priority.
Jacobs Lower Island site (side view) after completion in 2015. Note the fish passage channel in the foreground.
