TRUCKEE  (AP) — Some of the lowest season flows in the Truckee River in four decades are raising concerns about Nevada’s lingering drought.

The water trickling down from the melting mountain snowpack apparently reached its peak this past week, both sooner and smaller than normal.

Federal Water Master Chad Blanchard said it’s the third lowest peak for runoff since detailed records were kept starting about 40 years ago. The lowest were in 1977 and 1988.

“It’s pretty ugly,” he told the Reno Gazette-Journal (http://tinyurl.com/coy37lr).

The second dry winter in a row produced only about half the normal snowpack.

Blanchard said there’s no immediate concern for kayakers and fishermen because releases from Lake Tahoe and the Truckee River system’s other reservoirs should allow normal summer river flows to be maintained. But those flows likely will arrive earlier in the season as well.

Likewise, the same reservoir storage will guarantee normal water deliveries across the Reno-Sparks area through the summer — but the season could prove far more challenging for folks depending on water from rivers without reservoir storage, including the Carson River.

Lake Tahoe’s level may only rise three-tenths of a foot by June instead of the originally projected half-foot, Blanchard said. Tahoe could dip to near its natural rim by fall, cutting off the flow of water into the Truckee River.

Although the snowfall in the winter of 2011-2012 also was well below normal, much of the snow and rain fell late in the season. The opposite occurred this past winter with all the snow and rain coming early and shutting off in January.

January through March was the driest on record for the three-month period dating back more than a century in Tahoe City.

All those months of dryness produced poor conditions for runoff. Much of the moisture present in the snowpack is going directly from the snow into the atmosphere, a process similar to evaporation known as sublimation, Blanchard said. And much of the water melting from the snowpack is soaking into a dry ground rather than making it to rivers and streams.

“It’s caused a very inefficient runoff,” Blanchard said. “The snow is not responding very well right now. It shows how much a dry spring will affect the runoff from an existing snowpack.”