The National Weather Service in Anchorage reports that a Flood Advisory For A Glacier-Dammed Lake Outburst in effect until 2:30 p.m. Thursday for Snow River to Kenai Lake and down the Kenai River to Skilak Lake. Forecasters say that flooding caused by a glacier-dammed lake outburst continues.
Water will flow over Primrose Road (leading to Primrose Campground), likely becoming impassable to small vehicles and affecting campground access. Garages along Primrose Road may begin to flood. Water levels are expected to steadily rise tonight through Sunday and peak sometime Sunday night or Monday morning.
Sterling Highway Residences from Milepost 48 to 50 could see water in their yards. Cooper Landing boat launch “fish walk” could become submerged. Potential flooding of Quartz Creek boat ramp and adjacent campsites. Water levels in these areas are expected to crest Monday night or Tuesday.
Additionally, based on rising Snow River water levels and downstream water temperature, forecasters believe the Snow Glacier Dammed Lake began to release. Water levels on Snow River just upstream of Kenai Lake have risen 1.5 feet since 30 August. The hydrographic trend continues to rise steeply in the absence of relative precipitation.
The National Weather Service says that Snow Glacier Dammed Lake releases every other year; the last release was in October 2020.
The current water level on the Snow River is above 11 ft, gage datum, and is expected to rise an additional 2-3 feet with a crest near 13 ft early Monday. At this time Snow River water levels are expected to exceed bankfull, but below flood stage (16 ft, gage datum). Residents near the Snow River and the Kenai Lake confluence and Kenai Lake outlet should monitor local conditions and prepare for rising water levels.
The current water level on the Kenai River at Cooper Landing is above 11 ft, gage datum, and may be starting to rise. At this time, a peak 4-5 ft higher than present water level is expected. The forecast models suggest that by late Sunday, Kenai Lake outlet will reach Minor flood stage (13 ft, gage datum) and rise another 1 to 3 feet before the flood peak crests early Tuesday. Water level recession from flood stage should continue through the middle of the week before dropping below bank.
The flood wave is expected to dissipate by lake effects with only minor water level rises below Skilak Lake and no flood impacts.
Precautions include being aware of your surroundings and don’t drive on flooded roads.
NOTE: inherent uncertainty in initial glacier lake volume will result in varying crest height and timing (click this link for more information – http://www.weather.gov/safety/flood).