Flood — Kennebec, Maine

2023-05-01 to 2023-05-06 · near Augusta, Kennebec, Maine

Event narrative

The Kennebec River came out of banks and on May 1 and caused significant flooding to several businesses between Augusta and Gardiner. The discharge measured at the USGS river gage in Sydney, just upstream of Augusta, had a 10 year peak flow of 113,000 cfs, which is tied as the third highest streamflow with June 1, 1984 and exceeded only by the flood of 1987 and 1936. The river crested at 20.3 feet in Augusta and 16.8 feet in Hallowell, just shy of the 18 foot stage for major flood level. The flooding was the result of a basin average of 4.5 inches, most of which ran off from nearly saturated ground conditions.

The most significant impacts occurred in Gardiner along the confluence of the Cobbosseecontee Stream and the Kennebec River, both of which were running at flood levels. The overflow resulted in flooding of parking lots and basements between Water Street and Arcade Street and businesses south of Bridge Street and Main Avenue. Flood waters were reported of 2 to 3 feet deep in parking lots. Flooding was prevalent along Front Street in Augusta and Hallowell where basement flooding occurred along several businesses and apartment complexes, including a US Postal Service building. Over a dozen vehicles flooded after waters submerged parking lots. The impacts were most notable on the west bank of the Kennebec River with minimal impacts on the east bank.

Wider weather episode

A broad area of low pressure across the Great Lakes region stalled out well to the west of the region early on Sunday, April 30th. A secondary area of low pressure developed and moved up the Eastern Seaboard and tracked across interior New England from Sunday, April 30th through Monday, May 1st. Widespread heavy rainfall occurred, and flooding was enhanced for this weather event due to the seasonal timing of the rains with spring soils being high in moisture and vegetation still being dormant. These two factors lead to increased run-off. Rain started across southern and coastal areas early on Sunday April 30th, with the heaviest rainfall Sunday night into early Monday morning. The rainfall on Sunday produced limited flooding, but set the stage for what was to come by swelling rivers and filling ditches ahead of the heavier rain. Heavy rain started around 3 AM and continued through 10 AM Monday with rainfall rates between 1 to 1.5 inches an hour. This caused flooding to rapidly develop, resulting in widespread flash flooding. The rainfall ended by midday on Monday May 1st. Runoff spilled into tributary rivers and major rivers that led to ongoing flooding for the next several days with most rivers cresting late on Monday May 1st or on May 2nd. Public infrastructure impacts were widespread for the event with over $4.2 million in damage. Oxford and Androscoggin Counties reported the most monetary damage to roads for the event.

Another aspect of the system was a period of strong gusty winds Sunday night that started along the coastline and extended inland causing localized power outages and tree damage. Wind gusts of 50 mph were recorded at the Portland Jetport, and gusts to near 50 mph were also recorded inland. Strongest wind gusts up to 65 mph were reported across the Mid-coast region. Power outages were reported due to a few downed trees and numerous snapped tree limbs.

View location on OpenStreetMap → (44.3313, -69.7590)

Source: NOAA Storm Events Database, event_id 1102177. Narrative written by the NWS forecast office that issued the report.