Why does MMWD let water flow over the reservoir spillways? Isn't that wasting water?
The capacity of each reservoir is set by the elevation of the dam, which in turn is set by the water rights accorded to MMWD by the State of California (see next question). Once a reservoir is full, any additional water will flow naturally over the dam’s spillway. We don't have the legal or physical ability to hold on to that water.


When Lagunitas, Bon Tempe and Alpine are full, the overflow spills into other district reservoirs downstream. Water from Phoenix, Kent, Nicasio and Soulajule flows into local creeks where it provides many environmental benefits including habitat for endangered coho salmon and other fish and wildlife. Thus even water that goes over the spillways is put to good use.

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1. Why does MMWD ask customers to conserve water even when the reservoirs are at normal levels or above?
2. Why does MMWD let water flow over the reservoir spillways? Isn't that wasting water?
3. Can MMWD enlarge the reservoirs to hold more water by raising the dams?
4. Have MMWD’s reservoirs lost capacity due to sedimentation?
5. If sedimentation is found to be a problem, could the reservoirs be restored to their original capacity through dredging?
6. What is MMWD doing to maximize the amount of water in our reservoirs?