CHEYENNE, Wyo. (AP) — Fremont County residents and disaster response officials are making preparations for spring flooding during what could be the biggest runoff from the mountain snowpack in decades.

The Wind and Little Wind river watersheds have a high potential for flooding because of record snowpack that has accumulated in the surrounding Wind River Mountains, forecasts say. The cities of Hudson, Lander and Riverton are "under the gun this year," said Jim Fahey, a National Weather Service hydrologist.

"It may be an exceptionally long spring to say it mildly," county Emergency Management Coordinator Kathi Metzler said.

Spring flooding usually alternates year to year between the Wind and Little Wind rivers, she said.

"This time, because of the way the snow lays and stuff, it looks like we may end up with both rivers high at the same time depending on how it melts," she said.

This year's runoff could rival 1963 when flooding caused severe damage in Lander, city emergency management coordinator Nick Hudson said.

"So we've been doing some pre-stage planning and trying to get things set to up to where, whether we have the kind of flows that are expected or not, we still should be able to hopefully protect critical infrastructure and provide for public safety," Hudson said.

The city is preparing special flood barriers and diversions along the Middle Fork of the Popo Agie River, which runs through Lander.

Parts of Fremont County already saw flooding in February when unusually warm temperatures caused low-level snow cover to melt rapidly. Most of the snow is at higher elevations in the Wind River Mountains and has yet to start melting.

"People got a little bit of a taste of it then as far as what needs to happen and what the potential is," Hudson said.

Residents along rivers and streams are placing new sandbags to reinforce previous efforts to protect homes and property, officials say.

Elsewhere in Wyoming, the Upper Green River Basin also was expected to have a high potential for flooding, while sections of the Snake, Shoshone and Sweetwater river basins can expect moderate to high flooding.

Many of the areas most threatened within those four watersheds are lightly populated.

The Upper North Platte, Laramie, Little Snake, Powder and Tongue river basins have a low potential for snowmelt flooding.