since the 1980s, there has been interest in creating a large off-stream reservoir in the sacramento valley. 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.