U.S. Senator Michael Bennet, left, works with state soil scientist B.J. Shoup from the USDA’s Natural Resources Conservation Service office in Denver
U.S. Senator Michael Bennet, left, works with state soil scientist B.J. Shoup from the USDA's Natural Resources Conservation Service office in Denver to measure snow depth and water density at a survey site atop Berthoud Pass in March. (THE DENVER POST | Scott Willoughby)

Spring runoff flowing from this year's ample snowpack is expected to swell reservoirs along the Front Range, increasing the danger of flooding but easing concerns about drought, at least in part of the state.

Snowpack in the South Platte River Basin had been at 121 percent of average, but after snow fell over the recent Mother's Day weekend, that number reached 145 percent.

The snowpack in the Upper Colorado River Basin is now at 136 percent of average.

The recorded snowpack on May 13 ranks among the 10 highest for that date in the last 35 years, according to the National Weather Service.

In the Upper Colorado River Basin, snowpack rose from 104 percent of average on May 8 to 136 percent by May 13.

Average combined reservoir storage is about 90 percent of capacity in the South Platte Basin and 57 percent of capacity in the Upper Colorado River, according to the U.S. Agriculture Department's Natural Resources Conservation Service.

Peak runoff typically occurs between now and mid-June.

"All of the antecedent conditions for another flood are here," the National Weather Service said.

Due to sediment and debris that last year's floods left in creeks, rivers and streams, the risk of further flooding in the Front Range foothills is higher than normal.

Drought conditions have continued to improve through most of Colorado, but the southeast corner of the state remains dry.

Currently, about 2 percent of the state is classified under the most "exceptional" drought conditions, compared with almost 16 percent last year, according to the U.S. Drought Monitor.