PROJECT ALERT NOTICE (NY) Record and Major Flooding in New York

Date: Fri, 01 Nov 2019 14:52:27 EDT

Summary: Record and Major flooding in parts of the Southern Adirondacks and northern Mohawk Valley October 31-November 1.

Record and Major flooding occurred in parts of the Southern Adirondacks
and northern Mohawk Valley October 31-November 1 as a result of
3-5+ inches of rainfall last night. Record peaks were recorded along
the Sacandaga River near Hope, NY (01321000); West Canada Creek at
Kast Bridge, NY (01346000); and Mohawk River near Little Falls, NY
(01347000) in 107 years, 99 years, and 95 years of record, respectively.
Major flooding was also reported in parts of the Lake Champlain Basin
along the East Branch Ausable River at Au Sable Forks, NY (04275000).
About 30 USGS streamgages exceeded NWS Flood stages across central and
eastern parts of New York State.

Streams are receding in many locations, however, several areas are
forecast to remain above NWS Flood stage through Saturday, particularly
along West Canada Creek and the Mohawk River downstream of Hinckley
Reservoir and Delta Dam, and along the Sacandaga River and Upper
Hudson River.

A total of 10 USGS crews (20 staff members) from the Troy, Ithaca,
and Potsdam, NY offices are making numerous high-flow discharge
measurements today for rating calibrations and extensions, and
flood documentation. One USGS streamgage was damaged, although the
back-up sensor continued to operate, a few streamgages experienced
minor orifice damages, and one stream gage was partly inundated.

The approximate annual exceedence probability is 0.5% (>200-yr flood)
for Sacandaga River near Hope, NY (01321000) and West Canada Creek
at Kast Bridge, NY (01346000). The approximate annual exceedence
probability is 4% (25-yr flood) for several streamgages along the
Upper Hudson, Mohawk, and East Branch Ausable Rivers. Widespread
rainfall of 2-4 inches across eastern New York October 16-17
resulted in wet antecedent conditions and elevated streamflows
that contributed to the magnitude of flooding.

This is the last Project Alert for this high-flow event.