Albany County’s spring runoff has come later than usual, but the combination of sunny days this week and storms predicted for the weekend now has forecasters expecting the Laramie River will rise enough for minor flooding early next week.
National Weather Service Jim Fahey issued a hydrologic outlook Wednesday indicating that afternoon rain showers in the mountains are likely to occur between Thursday and Sunday, causing “the Laramie River at Laramie to rise to flood flows by early next week.”
Fahey predicts a “prolonged wet period” throughout the coming week is likely to keep the North Platte, Laramie and Medicine Bow rivers “at moderate to high levels through the end of next week.”
Fahey notes there’s still “very ripe snowpack” between at elevations between 9,000 and 10,000 feet and temperatures at that elevation are likely to rise above 60 degrees this week.
Where the Laramie River meets Laramie, the U.S. Geological Survey’s gauge indicates that streamflows had already reached the “action stage” by Monday this week.
In hydrology jargon, the action stage is the point where NWS or other officials need to take some mitigation action to prepare for any flooding.
As of 1 p.m. on Wednesday, the water depth in the Laramie River was 8.42 feet at Laramie. Minor flooding begins when the water levels hit 9 feet.
The water level is projected to drop below 8 feet by mid-Saturday before rising again into the action stage by Monday.
However, even if the Laramie River does rise above 9 feet next week, mitigation work in West Laramie and in the West Side that’s been completed in recent years means the river’s unlikely to damage structures until the water level above 10 feet — a water level which requires about double the volume of water the river’s currently carrying.
Where flooding along the Greenbelt once might easily have crept up toward Optimist Park and houses on the West Side, the city’s constructed berms should withstand all but the most extreme runoffs.
On the west side of the river, the Sunny Meadows Village trailer park and The Timbers are also now better projected by earthen protections built in recent years.
Many of the normal floodplains around town are already becoming saturated with water, but there’s still plenty more land that can take on much of next week’s runoff.
Aimee Binning, Albany County’s emergency management coordinator, said she’s been in frequent contact with city officials about possible mitigation efforts that might be needed, like damming off the Greenbelt.
As water levels rise, she said she’ll keep an eye on some of the private bridges in the area lest there’s a risk of debris sweeping them away.
Most of the imminent flooding that the county’s about to face, Binning said, is really “nuisance flooding,” the kind the just forces ranch-owners to move cattle to higher ground. Ultimately, she said this year’s run-off is likely to be a boon for irrigators since Wheatland Reservoirs 2 and 3 are likely to fill for the first time in a couple years.
The Laramie Basin’s snowpack barely exceeded the median this year, but cool weather and significant precipitation at the end of May delayed the bulk of region’s spring runoff.