South Delta Gates and Barriers Some Slides borrowed from Mark Holderman

Temporary Barriers Rock Barriers are installed seasonally on as needed basis Combination of weir/culverts (with flap gates) Objective: To protect water levels in South Delta and offset the effects of pumps offset the effects of pumps

History of Barrier Installations

Grant Line Canal Barrier

Head of Old River Barrier

SDIP Permanent Gates Bottom Hinged Bottom Hinged Provide more flexibility than temp. barriers Provide more flexibility than temp. barriers Objective: To protect water levels and water quality by creating better circulation in South Delta Objective: To protect water levels and water quality by creating better circulation in South Delta

Modified Plan C Basic Concept Operate Ag Barriers to Protect Water Levels and Improve Water Quality (on a as needed basis) The number of barriers operated depends on the hydrology The number of barriers operated depends on the hydrology All ag barriers fully open during flood tide All ag barriers fully open during flood tide Middle River and Old River Barriers are fully closed during ebb tide (When they are operated) Middle River and Old River Barriers are fully closed during ebb tide (When they are operated) Grant Line Canal Barrier only partially open during ebb- tide to prevent water level problems Grant Line Canal Barrier only partially open during ebb- tide to prevent water level problems

Plan C Barrier Operation Low SJR Flows (<2500 cfs) or HOR Operating Middle and Old River barriers closed during ebb tide Middle and Old River barriers closed during ebb tide GLC Barrier partially open during ebb tide GLC Barrier partially open during ebb tide

Plan C Barrier Operation Intermediate SJR Flows (2500<SJR<4000cfs) & HOR Open Old River barrier closed during ebb tide Old River barrier closed during ebb tide GLC Barrier partially open during ebb tide GLC Barrier partially open during ebb tide

Plan C Barrier Operation High SJR Flows (4000<SJR<8000cfs) and HOR Open GLC Barrier partially open during ebb tide GLC Barrier partially open during ebb tide

Plan C Barrier Operation Very High SJR Flows (>8000 cfs) and HOR Open No need to operate any Ag barriers No need to operate any Ag barriers