Stanford's lake water supply is the main source of irrigation water for the university, including athletic fields, the golf course, and campus landscaping. Creeks and lakes on Stanford property supply the non-potable water to a system of pump stations and pipelines for delivery to campus. This system also supports and distributes captured stormwater from facilities on campus, which began operation in 2019. Stanford wells supplement the surface water as needed, based on annual rainfall. This system dates back to the early days of the university and has been preserved and operated since then, reducing the amount of imported water that Stanford would otherwise need to meet its irrigation demand. To maintain the natural habitats of these sources, creek diversion facilities include provisions for accommodating fish passage and ecosystems, including fish ladders and screened intakes.