By Brandon Mercer

FREMONT (CBS SF) — An attack on an inflatable dam holding back precious stores of water on Alameda Creek let loose nearly 50,000,000 gallons of water, enough to serve 500 families for an entire year, said the Alameda County Water District (ACWD).

“This is a very significant loss of water under any circumstances, and more so in the drought conditions we are experiencing,” said ACWD General Manager Robert Shaver. “It is an utterly senseless, destructive, and wasteful thing to do.”

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The dam will cost $3 million to replace.

Fremont police report vandals accessed a restricted area early Thursday, irreversibly damaging the barrier holding back the water which was supposed to go into the Niles Cone Groundwater Basin where residents and businesses in Newark, Union City, and Fremont could access the critically needed supplies. 81,000 customers are in that area.

Instead, the water flowed into the San Francisco Bay.

The district tells CBS SF in a press release, “While the water loss was substantial, the District does not believe it will have a long-term impact on its water supply operations.”

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Inflatable Dam Across Alameda  Creek Before Its Destruction By Vandals In May 2015

Inflatable Dam Across Alameda Creek Before Its Destruction By Vandals In May 2015 (Alameda County Water District)

Anyone with information about this crime is encouraged to contact Detective A. Ceniceros at or (510) 790-6900.

The destroyed dam dates back to 1971, and because of its age, the district was already working to build a replacement and has vendors and equipment mobilized to do that.

It also maintains a second dam on the creek, used to expand and save water from going downstream when needed, or deflate, and allow storm run off to flow freely.

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150 acre feet of water was lost. Generally, an “acre-foot”–the amount of water used to fill an acre of land up to one foot, is thought to supply a suburban family of four for a year. In the Bay Area, it can last much farther. 325,850 gallons make up one single acre foot. The water district handles water for 340,000 people in the southern part of the county.