May 20, 2019
Excessive runoff into the Ottawa River Basin in Canada restricted the outlet of Lake Ontario. This combined with above normal precipitation into the Lake Ontario Basin, record levels on the Great Lakes above Lake Ontario, and higher than normal flows into the lake from the Niagara River pushed the lake to well above normal levels. Over the course of May, the levels quickly approached those reached in 2017.
Source: NOAA National Weather Service Storm Events Database (event 829714). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Jefferson County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.