The project includes annual maintenance of a river channel that was reconstructed in 2018 under a separate Streambed Alternation Agreement authorization that has since expired. The river channel is located upstream of YCWA’s South Canal Diversion and requires annual maintenance to ensure water supply reliability and enhanced fish passage. The project involves: (1) mobilization; (2) temporary access ramp installation; (3) construction of temporary berms to decrease turbidity; (4) river alluvium excavation; (5) spreading excavated river alluvium on the adjacent gravel bar; (6) cobble lining; and (7) site clean-up and demobilization. Maintenance work would occur annually, as needed, from April through August. Depending on storm events it is possible that up to two maintenance events would be needed each year, although it is unlikely. Due to the potential for severe impacts on water supply and agriculture, YCWA proposes to allow work to proceed outside of the typical work windows (i.e., between recession of winter/spring runoff and the start of irrigation season), as needed. This time period between runoff and the start of irrigation season typically occurs during the month of April through early May. If the annual
maintenance occurs before July 1, a fish avoidance plan will be prepared and submitted to CDFW for approval prior to any work being initiated. Once approved by CDFW, the fish avoidance plan will be adhered to as a means to avoid all listed fish species with the potential to occur in the project area.