Idaho’s snowpack is pegged at 80-100% of normal in most of the state, USDA’s Natural Resources Conservation Service said in a March 1 report.

But to maintain that level, at least normal storm activity is needed through March, NRCS said.

Above-normal rain and snow would be better everywhere and would especially benefit the Boise, Upper Snake and Southern Snake river basins.

Big Wood and Big Lost basins in the central mountains have good snowpack after two straight abnormally dry years. They need a wet spring to ensure adequate irrigation supplies due to low reservoir levels.

Hydrologists are encouraged by the recent arrival of more active weather, in contrast to the high pressure that kept conditions dry during much of January and February. They will watch how long this lasts and how far it extends into the southern region, where irrigated agriculture dominates.

NRCS said April and May rainfall and temperature patterns will strongly influence runoff efficiency.

Normal seasonal peak snowpack is still within reach for Little Wood, Lost, Salmon and Clearwater river basins as well as the state’s northern panhandle, said Daniel Tappa, hydrologist and data collection officer for the NRCS Snow Survey in Idaho.

“However, the ship has likely sailed on normal peak snowpack for our lower-elevation, southernmost basins, since these areas typically see peak snowpack in early March,” he said. Owyhee and Bruneau are examples.

NRCS said streamflow forecasts uniformly decreased since the Feb. 1 report. They call for below-normal flows for the Upper Snake, Southern Snake, Big Wood, Boise, Payette and Weiser basins.

Tappa said snow telemetry sites did not show widespread melting through February and into early March.

But runoff timing is hard to predict because most of the measurement sites are in protected terrain like heavily forested areas or have a northerly aspect, he said. There is much less data for south- and west-facing areas where snow may melt earlier.

Soil moisture is “a little bit of a mixed-bag picture,” Tappa said. It looks above normal through the central region and into the Upper Snake Basin to the east. Heavy precipitation in the fall helped, “but we could be in the beginning phase of some water from snowpack melting, and percolating into soil. That could be part of the signal, too.”

He said soil moisture is welcome, but there is concern runoff will be lower than anticipated. For example, some drought-shallowed groundwater tables need a boost.

“We need to fill some of that first before we get very efficient runoff into these river systems,” Tappa said.

In the Owyhee River Basin in parts of Oregon, Idaho and Nevada, “we have cause for hope in that we have a significant amount of snow and snow-water-equivalent out there now,” said Clancy Flynn, who manages Nyssa, Ore.-based Owyhee Irrigation District. “It’s stayed cold enough that it’s still there. If it warms up quickly with a little rain, we could see a year that is significantly better than worst-case scenario.”