SACRAMENTO (KCBS) – Heavy rains and snow this past winter has left rivers flowing higher than average and reservoirs near capacity.

READ MORE: Firefighters Working to Save Giant Sequoias Forced to Flee Advancing Flames

The California Department of Water Resources says that river flows range from about 20-percent above average in the Sacramento River near Shasta, to double the average flows in the San Joaquin and Kings Rivers.

David Rizzardo, the department’s chief of snow surveys and water supply forecasting said the heat wave is causing even more runoff.

• ALSO READ: Heat Wave Sets New Record Highs In 9 Bay Area Cities

“This heat wave we’re getting is certainly taking its toll, and the rivers are coming down very fast, and the reservoirs are having to pass along some of that flow further downstream into the valley,” Rizzardo told KCBS.

READ MORE: San Mateo Deputies Arrest Man Suspected in Stabbing Attack With Wood Stake

Rizzardo warned this is not the summer to swim in the rivers. “It’s nothing to play around with, that’s for sure,” he said.

And high in the Sierra Nevada, there is still quite a bit of snow that’s ready to melt.

Rizzardo said that at the highest elevations, there is still a couple feet of snow that’s ready to melt, and some roads and passes are still not accessible as the summer recreation season starts.

The runoff could continue well into July and possibly even August.

MORE NEWS: UPDATE: Southbound Hwy 17 Lanes Cleared After Woman Jumps Off Pedestrian Bridge

Rizzardo says there’s always risk of flooding in conditions such as these. But as of now, the reservoirs are prepared and have made room for higher than average inflows.