Why is water being released from Lopez Dam?
There are four key reasons Lopez Dam releases water downstream:

  1. The California Fish and Game Code, Section 5937, requires: “The owner of any dam shall allow sufficient water at all times to pass through a fishway, or in the absence of a fishway, allow sufficient water to pass over, around or through the dam, to keep in good condition any fish that may be planted or exist below the dam.” Since Lopez Dam does not have a fishway (fish ladder), downstream releases are made through pipes that pass through the dam.
  2. The Federal Endangered Species Act. Federal Law prohibits any action that would result in the “take” ("The term 'take' means to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct."). Steelhead were declared a Threatened Species in 1995 and Arroyo Grande Creek supports a population of the fish. Shutting off downstream releases would dry up the upper part of the creek and result in harm to steelhead in the area, thereby violating federal law.
  3. Downstream Water Rights. Landowners, primarily farmers, whose land abuts the creek have a legal right under section 10 of the California Constitution to the natural flow of water in the creek, so long as the farmers use the water for reasonable and beneficial uses. If flows from the dam are stopped, farmers and landowners in the upper portions of the Arroyo Grande Valley would not be able to exercise their water rights. In the winter, when flows in the creek are above the amount needed by the farmers, the “extra” water is stored in the reservoir above the dam.
  4. In addition to the legal requirements, it is important to note that the water released from the dam increases the amount that recharges the groundwater basin below the dam. This groundwater is used by landowners as well as downstream municipalities in addition to supplies from Lopez Lake.

Show All Answers

1. Why is water being released from Lopez Dam?
2. How much water is released downstream from Lopez Dam?
3. Is there a plan to reduce releases if the water gets very low in the reservoir?
4. Do other reservoirs make similar releases?