Great South Bay at West Sayville (IN MLLW)

Highest listed crest 16.75 ftFlood stage 3.1 ft10 crests since 1938

The Great South Bay at West Sayville (IN MLLW) crested at major flood stage 10 times among the 10 crests the National Weather Service lists from 1938 to 2012. The highest, 16.75 ft on September 21, 1938, was major flooding, 13.65 feet above flood stage.

The gauge

Highest listed crest: 16.75 ft; September 21, 1938
Flood stage: 3.1 ft; Major flooding from 4.1 ft
Crests at major: 10; 9th of 160 gauges in New York
Most recent flood crest: October 29, 2012; 14.31 ft, major flooding
Location: Suffolk County; Near Patchogue (4.8 mi), Lake Grove (9.6 mi), Babylon (12.4 mi)
Identifiers: NWS SAYN6; USGS 01306402

Flood stages

The thresholds the National Weather Service uses for this gauge today, and how many listed crests reached each.

Flood categories, Great South Bay at West Sayville (IN MLLW)

Flood stage (minor)	3.1	0	—	Minimal or no property damage, but possibly some public threat
Moderate flood stage	3.6	0	—	Some inundation of structures and roads near the stream
Major flood stage	4.1	10	Oct 29, 2012	Extensive inundation of structures and roads

Every listed crest

10 crests from 1938 to 2012. Filled: at or above flood stage. Hover a crest for its date and stage.

Crests at or above flood stage, by decade

These are the crests the local National Weather Service office lists for the gauge: the highest on record and recent crests. Lesser floods between them may be missing, so counts by decade are a floor.
Categories use today's flood stages. Levees, dams and channel changes since a crest can make old and new stages not directly comparable.

Highest crests

Highest listed crests, Great South Bay at West Sayville (IN MLLW)

1	Sep 21, 1938	16.75	+13.65	Major	—
2	Aug 31, 1954	14.76	+11.66	Major	—
3	Oct 29, 2012	14.31	+11.21	Major	—
4	Dec 11, 1992	14.29	+11.19	Major	—
5	Feb 7, 1978	13.60	+10.50	Major	—
6	Nov 25, 1950	13.05	+9.95	Major	—
7	Nov 12, 1968	12.95	+9.85	Major	—
8	Oct 19, 1996	12.70	+9.60	Major	—
9	Oct 25, 1980	12.68	+9.58	Major	—
10	Feb 19, 1972	12.41	+9.31	Major	—

Other gauges in Suffolk County

Flood gauges in Suffolk County

Old Field (IN MLLW)	9.2	10.12 ft, Oct 29, 2012	0
Great South Bay at Lindenhurst (IN MLLW)	3.1	7.73 ft, Oct 29, 2012	2
Great South Bay at Watch Hill (IN MLLW)	3.2	7.73 ft, Oct 29, 2012	1
Moriches Bay at Moriches Bay (IN MLLW)	4.3	7.73 ft, Oct 29, 2012	1
Orient (IN MLLW)	4.8	10.12 ft, Oct 29, 2012	2
Riverhead (IN MLLW)	5.7	10.12 ft, Oct 29, 2012	2
Shelter Island (IN MLLW)	5.1	7.73 ft, Oct 29, 2012	1
Shinnecock Bay at Ponquogue (IN MLLW)	4.9	7.73 ft, Oct 29, 2012	1

Suffolk County: every hazard · River floods across the country · New York

NOAA National Water Prediction Service, gauge SAYN6, retrieved October 30, 2026. Stages in feet on the gauge's own datum, not elevation. Crests are as the National Weather Service lists them; preliminary values may be revised.