Poison Creek Diversion/Fish Passage

Overall actions included, construction of a single fish passable permanent diversion structure by IDFG, installation of a single fish screen at the point of diversion (POD) by IDFG, 4.16 miles of water conveyance pipeline conveying 2.4 cfs to supply three gravity fed pivot irrigation machines and ten in-line pod irrigation lines covering a total of 163 acres (the total point-of-use (POU) footprint acres remain the same though the shape of the POU changed to accommodate the new sprinkler irrigation system). The landowner removed two of the diversions (SPoC-01 and SPoC-03) from Poison Creek. Diversion SPoC-02 was removed by natural events during spring runoff prior to the project beginning. Smith Gulch diversion system, SPSG-01, was improved for efficient water delivery.

The outcome of this project was the conversion of open ditch water delivery into an enclosed irrigation pipeline system to provide adequate water quantity in the stream for rearing and spawning. As a result of changing the water delivery system three diversion dams (one wooden headgate and two tarp/wood) were removed and consolidated to a single point-of-diversion (POD). The consolidation of diversions allowed for the installation of a single fish screen at the POD by the Idaho Department of Fish and Game (IDFG). The improvement of the Smith Gulch diversion and delivery system allow for water control and delivery without introducing the warmer temperature water from natural warm springs and pond overflow upstream.

As a result of these actions, the various channel wide diversion dams across the creek at three separate locations are no longer needed to divert irrigation water, thereby eliminating three fish passage barriers and opening up access to1.6 miles (from the mouth to the highest barrier) of high quality cool water habitat shaded by mature cottonwoods. An additional 1.4 miles opened up from the lowest barrier to the new point-of-diversion. This increased available habitat for ESA listed fish by 3.5 times. Also, temperatures will be maintained in main Poison Creek due to the diversion of the warmer water from Smith Gulch.

Benefits to anadromus fish will be occur through the increased water quantity during irrigation season as a result of the irrigation improvement practices. Increase water quality by reducing sediment input into Poison Creek.through the fencing of the spring and development of the livestock water system. Elimination of entrainment, mechanical injury, and removal of passage barriers will contribute to opening up 1.6 miles spawning and rearing habitat.