Long Island Sound near New London Harbor (IN MLLW)

Highest listed crest 10.58 ftFlood stage 5.0 ft5 crests since 1938

The Long Island Sound near New London Harbor (IN MLLW) crested at major flood stage 3 times among the 5 crests the National Weather Service lists from 1938 to 2012. The highest, 10.58 ft on September 21, 1938, was major flooding, 5.58 feet above flood stage. 2 other gauges on the Long Island Sound crested above flood stage within a week of it, 2 at their own highest listed crest.

The gauge

Highest listed crest: 10.58 ft; September 21, 1938
Flood stage: 5.0 ft; Major flooding from 7.8 ft
Crests at major: 3; 10th of 26 gauges in Connecticut
Most recent flood crest: October 29, 2012; 8.04 ft, major flooding
Location: New London County; Near New London (1.9 mi), Groton (2.9 mi), Norwich (12.9 mi)
Identifiers: NWS NLHC3; USGS 8461490

Flood stages

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

Flood categories, Long Island Sound near New London Harbor (IN MLLW)

Flood stage (minor)	5.0	0	—	Minimal or no property damage, but possibly some public threat
Moderate flood stage	6.0	2	Nov 25, 1950	Some inundation of structures and roads near the stream
Major flood stage	7.8	3	Oct 29, 2012	Extensive inundation of structures and roads

Every listed crest

5 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, Long Island Sound near New London Harbor (IN MLLW)

1	Sep 21, 1938	10.58	+5.58	Major	—
2	Aug 31, 1954	9.58	+4.58	Major	—
3	Oct 29, 2012	8.04	+3.04	Major	—
4	Nov 25, 1950	7.58	+2.58	Moderate	—
5	Sep 14, 1944	7.08	+2.08	Moderate	—

The worst floods along the Long Island Sound

For this gauge's highest crests, the other gauges on the Long Island Sound that crested above flood stage within a week.

September 21, 1938: 10.58 ft here, major flooding

Sands Point (IN MLLW)NY · Sep 21, 1938 · 16.75 ft · Major · its highest
New Haven (IN MLLW)CT · Sep 21, 1938 · 10.58 ft · Moderate · its highest

August 31, 1954: 9.58 ft here, major flooding

Sands Point (IN MLLW)NY · Aug 31, 1954 · 14.76 ft · Major
New Haven (IN MLLW)CT · Aug 31, 1954 · 9.58 ft · Moderate

October 29, 2012: 8.04 ft here, major flooding

Sands Point (IN MLLW)NY · Oct 29, 2012 · 14.31 ft · Major
Bridgeport Harbor (IN MLLW)CT · Oct 29, 2012 · 13.26 ft · Major · its highest

Gauges on the Long Island Sound

Flood gauges sharing the river's name, linked within 80 miles of one another.

Flood gauges on the Long Island Sound

New Haven (IN MLLW)	CT	8.7	10.58 ft, Sep 21, 1938	0
Sands Point (IN MLLW)	NY	10.0	16.75 ft, Sep 21, 1938	10
Bridgeport Harbor (IN MLLW)	CT	8.7	13.26 ft, Oct 29, 2012	3
New London Harbor (IN MLLW) this gauge	CT	5.0	10.58 ft, Sep 21, 1938	3

Other gauges in New London County

Flood gauges in New London County

Jewett City	17.5	29.00 ft, Aug 20, 1955	4
Yantic	9.0	14.88 ft, Jun 5, 1982	12

New London County: every hazard · River floods across the country · Connecticut

NOAA National Water Prediction Service, gauge NLHC3, 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.