Water "skimmed" off high winter flows in the Sacramento River would be pumped into a storage basin in the western side of the valley known as Sites Reservoir. The reservoir would hold about of water to be released into the Sacramento River during low-flow periods, boosting the water supply available for SWP entitlement holders and improving water quality in the Sacramento–San Joaquin Delta. This project has previously arisen in several forms, including proposals for a Glenn Reservoir or the Glenn-Colusa Complex on nearby streams, which would also have been receiving reservoirs for water sent east through the Dos Rios Project's Grindstone Tunnel or other transfers from North Coast rivers. With its large storage capacity, Sites Reservoir would increase the production and flexibility of California's water management system, yielding of new water per year. This project is being seriously considered by the Department of Water Resources, as California's water system is expected to face serious shortfalls of per year by 2020. However, the project has been criticized for its high cost, and potential disruption of fish migration when large amounts of water are drawn from the Sacramento River during the wet season. The Los Banos Grandes reservoir was first proposed in 1983 and would have served a similar purpose to Sites. The reservoir would have been located along the California Aqueduct several miles south of San Luis Reservoir, and would have allowed for the storage of water during wet years when extra water could be pumped from the Sacramento–San Joaquin Delta. Pumped-storage hydroelectric plants would have been built between Los Banos Grandes and the existing Los Banos flood control reservoir, and between that reservoir and the aqueduct. The current status of Los Banos Grandes remains uncertain, as the DWR has been unable to appropriate funding since the 1990s. The existing SWP facilities are collectively known as Stage I. Stage II, which includes such works as the Peripheral Canal and Sites Reservoir, was to have been built beginning in the late 1970s and 1980s – but due to concerted opposition from Northern Californians, environmentalist groups and some economic interests, as well as the state's increasing debt, attempts to begin construction have all met with failure. Parties currently receiving SWP water are also opposed to its expansion, because water rates could be raised up to 300 percent to help pay for the cost. As a result, SWP capacity falls short by an average of each year; contractors only occasionally receive their full shares of water. The disparity of costs to the project's various constituents has been a frequent source of controversy.