The Truckee River is flowing through Reno and Sparks at a high rate, but the volume of water is not coming from spring run-off yet. 

"We're accumulating. We're not melting much yet," Chad Blanchard, U.S. District Court Water Master said.

The water is coming from upstream reservoirs.

"We're having to pass quite a bit of water through the reservoirs," Blanchard said. "We cannot store yet at Prosser, Stampede and Boca because of flood control."

Those reservoirs are used for flood control and for storage of water supply.  Boca is about 75 percent full and Stampede is about 80 percent full, and with snowpack exceeding 200 percent of average, more space is needed.

"We don't want a lot of water," Blanchard said. "We need to pass water through right now and store more later."

The Water Master cannot allow river flows to exceed 6,000 cubic feet per second, so the amount of water drained from the reservoirs takes some balance.

"If we exceed 6,000 cfs, in the river, we have to cut back on the releases," Blanchard said. "So, we have to try to get out water when we can, when there's room in the river."

Lake Tahoe was more than six inches below its natural rim in mid-October.  Throughout the winter, it has risen more than feet and the snowmelt has not even started.  A rise of 18 more inches will completely fill the lake. 

"But we could still have three more feet come," Blanchard said. "So, we're trying to pass water now and trying to really limit the rate of rise on the lake."

Once the snow has completely melted, Lake Tahoe will reach its limit, rising more than 6.5 feet since October.

"This will be the largest physical rise on Lake Tahoe, ever," Blanchard said.

The rate of rise depends on the snowmelt. Blanchard says on a typical warm day, about two inches of water will melt out of the snowpack.  How much that affects the lake and reservoir levels varies, depending on how far the snow is spread out, and the elevation.

"It's just a matter of how much surface area is covered when we start getting those warm days when we get up to the maximum melt," Blanchard said.

Water is flowing through the Tahoe City Dam at 1,000 cfs, and while water is also being released from the other reservoirs, Blanchard expects all of them to be completely full by the end of the spring run-off.