Police in Fremont, California, are trying to figure out who deflated a rubber dam on Alameda Creek Thursday morning, letting nearly 50 million gallons of drinking water flow out.

The lost amount is enough water for 500 homes for a whole year, Alameda County Water District general manager Robert Shaver said Friday.

"It's shocking that someone would do this, given our current situation. Our drought is so severe," Fremont-resident Emily Kunkel said. "I don't understand why anyone would do that."

Investigators don't have a motive yet and don't know whether this was the work of vandals or an act of terrorism.

The dam was inside a secured area where no trespassing signs are posted. But nearby residents said vandals have recently struck in the area.

"Fiber cables, AT&T U-verse being cut twice in the last eight to nine months," Fremont resident Karl Melzner said. "The second one was just six weeks ago."

Fremont Mayor Bill Harrison said state and federal leaders are not doing enough to protect vulnerable infrastructure.

Harrison pointed to the attack at a South Bay PG&E substation and to the serial stowaway who managed to sneak past security and board a plane at Mineta San Jose International Airport.

Harrison said the dam is just the latest example of what's sorely lacking: funding to protect infrastructure.

"Hopefully items like this will raise attention to not just local leaders, but to state and federal leaders, that we need more money for infrastructure to make sure that our city and our regions are safe," Harrison said. "We need to make sure we’re investing in infrastructure or things like this are just going to continue to happen."