Even as the spring heat wave that’s thawed California’s record Sierra Nevada snowpack comes to a close, communities across the Central Valley and the state’s northeastern mountains are continuing to prepare for potentially dangerous flooding.

Already, near-overflowing rivers triggered the closure of much of Yosemite National Park on Friday. The Yosemite Valley, home to many of the famous cliffs and waterfalls in the park, was expected to reopen for day use only this morning before a full opening Monday morning, when a flood watch for the area was set to expire.

Indefinite flood warnings were also in effect for areas near rushing rivers in parts of Fresno, Kings and Tulare counties, where some 60,000 acres of farmland are under about 3 feet of water brought by last month’s powerful atmospheric river storms.

The high temperatures, breaking 80 degrees at many snowy peaks, were expected to subside by Monday. But that won’t put an end to flood concerns triggered by anticipation of the “Big Melt.”

“The rate of melting may not be as significant, but it will continue,” said Scott Roe, a meteorologist with the National Weather Service office in Sacramento. “There will be high flows in waterways for the foreseeable future.”

Huge swaths of the Lake Tahoe area, as well as Lassen and Plumas to the north and Mono County to south, are under a flood watch, one level below a warning.

One of the rivers at the highest risk of overflowing, the Merced River, was expected to crest its banks in Yosemite early this morning and potentially again on Monday, according to the National Oceanic and Atmospheric Administration

The river wasn’t forecast to reach above 11 feet, but if it hits 12 feet at the Pohono Bridge, it would flood the main roads in and out of Yosemite Valley.

But the more significant flood danger is in the Tulare Basin of the Central Valley, where the long-dry Tulare Lake — once the largest freshwater lake west of the Mississippi River — has been replenished after reservoirs failed to contain this winter’s rains.

That flooded agricultural communities and farmland but returned natural habitat to the flood plain, a boon for native fish and wildlife that have struggled after years of drought.

“This is throwing them a big lifeline,” said Jon Rosenfield, a biologist with conservation advocacy group San Francisco Bay Keeper.

In Kings County, residents in low-lying areas near the rising rivers have been placing sandbags on their properties and moving items to higher ground to prepare. With cooler weather expected, some have breathed a sigh of relief, said Kings County Supervisor Doug Verboon

“There is no immediate concern, and I believe the cold weather next week is going to really help us out,” Verboon said. “Right now, the anxiety has been reduced and I think we’re looking pretty good.”

California’s state climatologist said last week that the state’s communities won’t likely see imminent flooding from the week’s heat wave as upstream reservoirs can accommodate the inflow of melting snow.

But with so much water coursing through rivers that flow out toward the Pacific Ocean and feed Tulare Lake, officials have warned that a breach in a levee could cause flooding, regardless of temperatures.

The Kings River is off limits due to swift-moving water as more water has been released upstream from the Pine Flat Reservoir to make way for melting snow, Verboon said.

Officials from the State Office of Emergency Services said they are working with local authorities in the Tulare Lake Basin area to prepare for more flooding.

They’ve been mapping out the locations of wastewater treatment plants, hospitals, prisons and other sensitive areas, and are planning with local fire departments for places to set up shelters or position rescue crews.

Rosenfield, the biologist, said that as catastrophic weather events are likely to become more frequent amid a warming climate, the state may also need to reconsider how it manages its water resources.

“The message nature is trying to give us,” he said, “is we really need to learn to live within the limits of where we live and where we plant.”

The Associated Press contributed to this report.