The Vern Freeman Diversion Dam, built by United Water in 1991 on the Santa Clara river, channels water to shallow basins designed to replenish the aquifer. For decades before the structure was built, earthen dams were constructed in the river to divert water to farmers and replenished the aquifer. The berms would have to be rebuilt whenever winter rains created a flow that breached the berms. Southern California Steelhead were declared endangered in 1997 and the fish ladder on the structure was deemed insufficient. The National Marine Fisheries Service determined that fixing this was a high priority since it is the first structure the steelhead encounter when attempting to migrate from the ocean.