A new report offers reasons behind the Boise River's high water levels, which are expected to last for another week after rainfall and as temperatures rise next week.
The Natural Resources Conservation Service, a division of the U.S. Department of Agriculture, has released the new water supply outlook report, which attributed the rise in water levels to March snowmelt.
The NRCS wrote:
Mountain temperatures reached 70-75 F for several consecutive days and valley temperatures reached into the low 90s F in Boise. Using long-term valley weather station data as a gauge, this heat wave was likely the hottest in April since 1875. With the snowpack ripe, this heat created record high melt rates of an inch/day in April.
Heavy snowmelt was followed by colder temperatures and heavier-than-expected rainfall, with the river reaching a height of 10.86 feet as of this morning; flood level is considered 10.1 feet. The USGS has a webcam for viewing the river here.