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Cooper River at Charleston Harbor (IN MLLW)

National Weather Service gauge CHTS1 · South Carolina · Charleston County · 32.7750, -79.9240

Stage at this gauge is reported IN MLLW.

Flood levels

Official flood levels at this gauge: action stage begins at 6.5 ft; minor flooding begins at 7.0 ft; moderate flooding begins at 7.5 ft; major flooding begins at 8.0 ft.

Action stage6.5 ft
Minor flooding7.0 ft
Moderate flooding7.5 ft
Major flooding8.0 ft

Highest recorded crests

What the water does

National Weather Service impact statements for this gauge, in the Weather Service's own words.

7.0 ftAt 7.0 ft MLLW, minor coastal flooding typically begins. Minor flooding on roadways around Downtown Charleston occurs, possibly including Lockwood Drive, Wentworth and Barre, Fishburne and Hagood, and Morrison Drive. As the tide height approaches 7.5 ft MLLW, roads can become impassable and closed. Other impacts outside of Downtown Charleston include minor flooding of low-lying locations near area beaches including Isle of Palms, Sullivan's Island, Folly Beach, Kiawah Island, and Edisto Island.
7.5 ftAt 7.5 ft MLLW, moderate coastal flooding occurs. In Downtown Charleston, additional impacted roads include HW-17 at HW-61, Market Street, East Bay, Rutledge, and areas around MUSC. Other impacted areas include Long Point Road near Palmetto Islands County Park, locations around the Naval Complex, 12th and 15th Streets on Isle of Palms, and the road leading to Bohicket Marina on Seabrook Island. In Beaufort County, flooding will impact Hunting Island and the Sea Island Parkway near Chowan Creek Bridge.
8.0 ftAt 8.0 ft MLLW, major coastal flooding occurs. Widespread flooding occurs in Downtown Charleston with numerous roads flooded and impassable and some impact to structures. Impacts become more extensive all along the southeast South Carolina coast including erosion at area beaches, with limited or no access to docks, piers, and some islands.
8.1 ftPeak tide level reached in association with Hurricane Gracie which made landfall near Edisto Island, SC as a Category 4 hurricane on September 29th, 1959.
8.2 ftPeak tide level reached in association with an unnamed hurricane that made landfall near Ossabaw Island, GA as a Category 2 hurricane on October 15th, 1947.
8.6 ftPeak tide level reached in association with Hurricane David which made landfall near Sapelo Island, GA as a Category 1 hurricane on September 4th, 1979.
9.2 ftPeak tide level reached in association with Tropical Storm Idalia on August 30th, 2023.
9.3 ftPeak tide level reached in association with Hurricane Matthew which made landfall near McClellanville, SC as a Category 1 hurricane on October 8th, 2016.
9.9 ftPeak tide level reached in association with a strong area of low pressure on December 17th, 2023. Ranks as the highest non-tropical tide level on record.
9.9 ftPeak tide level reached in association with Tropical Storm Irma on September 11th, 2017.
10.2 ftPeak tide level reached in association with an unnamed hurricane that made landfall near Hilton Head Island, SC as a Category 2 hurricane on August 11th, 1940.
12.5 ftRecord tide level reached in association with Hurricane Hugo which made landfall at Sullivans Island, SC as a Category 4 hurricane at midnight September 22nd, 1989.

Forecast office: NWS North Charleston · River Forecast Center: Southeast River Forecast Center.

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