After the 1954 Huai River great flood, the upstream reservoirs including Banqiao were extended, constructed and consolidated.

The position of X2 is carefully monitored and maintained by releasing water from upstream reservoirs in anticipation of export demand.

Water now stored in upstream reservoirs is released in the spring for farms that lie between Reno and the lake.

The hopper is closed and is connected to an upstream reservoir.

Caught in the middle is the corps, which controls how much water is released from upstream reservoirs after each year's snow melt - and when.

With record-breaking demand for power to run air-conditioners, two hydroelectric power plants in the Upper Delaware Basin need a lot more water from upstream reservoirs.

The Salinas River itself is a sand river, so water appears on the surface only during heavy rains or when water is released from the upstream reservoirs.

An upstream reservoir to hold back flood water was also proposed.

Preventative flood control measures include upstream reservoirs that can also serve irrigation needs and produce hydroelectric power.

To augment the river's natural flow, the utilities began in 1999 to release water from two upstream reservoirs.