Coastal Flood in Kuskokwim Delta, Alaska

Between August 15 and 18, water levels exceeded one foot over the normal highest water line during each high tide cycle in both Kwigillingok and Kipnuk. The highest water levels were recorded by tide gauges in both of these communities on the 18th, reaching 2.6 ft above mean higher high water (MHHW) in Kwigillingok and 3.5 ft above MHHW in Kipnuk. A local measuring stake reached around 4 ft in Kipnuk.

In Kwigillingok, social media and FAA webcam imagery show water levels reached up to the boardwalk, moving boats and other property left on normally dry, low-lying areas. A large fuel tank was displaced. In Kipnuk, a local official reported that water entered the first floor of a house along the slough, a wooden shack along the riverbank was washed away, a 500 gallon fuel storage tank floated away, and portions of the public boardwalk system were damaged. An unsecured heating oil tank also spilled, releasing less than 55 gallons. Increased rates of erosion were observed as a result of the storm, which damaged the barge landing.

Two Bering Sea low pressure systems tracked into Western Alaska from August 15 through 18th bringing a period of nearly-persistent southerly winds which led to storm surge and coastal flooding along the Kuskokwim Delta coast and backed up flow along the lower Kuskokwim River. Abundant moisture drawn from the tropical West Pacific by both lows squeezed out moderate to heavy rain in Southwest Alaska, which exacerbated flooding issues along the Kuskokwim River. Flooding was most severe on August 18 as the second low began to enter the Bering Strait, bringing the strongest push of south to southwesterly onshore winds. Coastal communities experienced high water levels which inundated boardwalks, flooded subsistence structures, toppled fuel tanks, damaged ATVs and snowmobiles, and affected the foundations of homes. Along the Kuskokwim River, roads were inundated and closed and at least two houses were flooded in the community of Tuntutuliak.