(NewsNation) — Corcoran, California, is an agricultural town of just over 20,000 people where a celebration of freedom and veterans is planned for the weekend. But “the big melt” could soon put the whole town underwater.

“It’s a slow, uncertain process but with the amount of snow that we have behind us in the Sierra Nevada, we know it’s coming. We just don’t know how much and we don’t know how fast,” city manager Greg Gatzka said.

This year, the Sierra snowpack measured 300% above average in some parts. And with the warmer weather, the flooding is expected to go from bad to worse.

“It takes about a week for that melt to make it down to the Tulare lake area. But we already knew that. We have a two to three month maybe window period,” Gatzka says.

Corcoran is now racing to heighten and strengthen the 14-mile levee to prevent the town from drowning.

The “big melt” is expected to push water against the levee for about two full years before things drain and dry out again.

Just next to the levee is a California state prison complex which houses about 8,000 inmates. Corrections officials say they’re closely monitoring the situation and have stopped accepting transfers in the event that they need to evacuate.

California Gov. Gavin Newsom was in Corcoran this week to assess the situation and promise state support.

“Where we’re standing likely will be under water in a matter of weeks, if not months,” Newsom said in a press conference.

The city of Corcoran is desperate for emergency funding, hoping to be fortified fast enough to protect the city.

“If that levee goes, the city goes, the prison goes, the whole thing goes,” said Republican California Rep. Devon Mathis. “If it goes and it washes out, it’s going to be years before that area is, you know, production is able to take place.”