But what if the mountains don’t deliver on schedule? What if persistent cool weather holds snow on Cascade Mountain peaks weeks longer than normal? And what if spring rainfall falls short?

Skiers rejoice. But come Memorial Day weekend, drivers who tow ski boats to human-created lakes behind Western Washington dams may have to find other places to go.

“Our reservoirs are very low,” Tacoma Power spokeswoman Chris Gleason said last week. For example, the water level in Riffe Lake in Lewis County, is 50 feet below normal for this time of year. At Lake Cushman in Mason County, it’s 15 feet below normal. At Alder Lake, near Elbe in Pierce County, it’s also about 15 feet lower.

“There’s a lot of snow, but we haven’t had a lot of rain,” Gleason said.

Usually, melting snows and spring rains combine to fill the lakes before the summer recreation season, said Todd Lloyd, the utility’s power analyst.

So even though current measurements of mountain snowpack throughout Washington exceed historical levels, the delayed melting and scant recent rainfall together mimic a drought.

A SEVEN-YEAR LOW

On the Cowlitz River, which feeds Riffe Lake, the water level hasn’t been this low since the 2001 drought, Lloyd said.

That’s a troubling comparison for power managers. 2001 was a crisis year for energy supplies. During the winter of 2000-2001, too little snow fell in the mountains to fill the reservoirs behind hydroelectric dams, so power managers like Lloyd struggled to meet electrical demand.

At this point, that’s not an issue. “We’re meeting our loads right now,” he said.

The Natural Resources Conservation Service, an arm of the federal Department of Agriculture, began measuring mountain snowpack decades ago to help farmers who irrigate. Water supply specialist Scott Pattee, who’s based in Skagit County, tracks the relationship between snowpack, rivers and streams and reservoir supplies.

“April stream flow data, it’s just way, way down,” Pattee said as he prepared his monthly report for the entire state. Many of the dozens of snowpack stations he monitors have set records for accumulations at this time of year. “It’s not melting, and it should be,” he said.

‘IT’S NOT MELTING’

Experts blame the delay on lower-than-normal April temperatures. Also, total April precipitation did not measure up to historical averages.

So it’s not just Tacoma Power. Pattee’s data show many Washington reservoirs are low.

“That’s not to say they won’t fill slowly,” said Tom Fero, a senior hydrologist with the Northwest River Forecast Center, a National Weather Service agency in Portland.

Patience is key, said Jim Marron, a Natural Resources Conservation Service hydrologist, also in Portland.

“It’s a really good year for late snowpack. It is unusual from the aspect that it’s not melting. But from a water-supply standpoint, that’s not a bad thing,” he said. The late melt could reduce the effect of evaporation, leaving more water in the rivers for power production, as well as fish, later in the summer, he said.

Mountain snows usually begin to melt between March and mid-April. By the end of April, it was already two weeks late, Marron said. It’s too early to say whether this year will set any records for delayed melting. He and others at the Natural Resources Conservation Service said they won’t know until it happens.

“It probably will come at a time when they (the utilities) can best use it,” he said. “It tends to line up with demand a little better.” That way, when people seek relief from summer heat and turn up the air conditioning, utilities such as Tacoma Power will have plenty of electricity to sell, Marron said.

Meanwhile, the likelihood of spring floods is “extremely remote,” said Dana Felton, a National Weather Service meteorologist in Seattle.

On April 30, meteorologists came out with their latest 30-day outlook. The forecast: below-normal temperatures and precipitation.

“Now may be the peak of the snowpack,” Marron said. “But the way things have been going, who knows?”

Susan Gordon: 253-597-8756