Mermentau River at Mermentau, LA

The last 7 days and the forecast

NWS forecast issued Mon, Oct 12, 10:10 AM. Forecasts change as rain falls and as upstream water arrives.

Flood stages

What floods at each level

From the National Weather Service, highest first.

• 16 ftBetween 16 and 17 ft, flood waters reach the gauge over the mermentau river.
• 15.1 ftBetween 15.1 and 16.0 ft, flood waters reach the base of the southern pacific railroad bridge east of mermentau across an unnamed tributary.
• 14.3 ftThe river is at its flood of record. Widespread major to catastrophic flooding will occur.
• 13.4 ftThe river is near its 100 year flood level. Most of the community of mermentau is inundated with flood waters.
• 13.3 ftWater reaches the roadway of the of U.S. 90 bridge east of Mermentau.
• 10 ftWidespread flooding over a large area from Interstate 10 to Lake Arthur with numerous homes and roads flooded. The community of Morse will be inundated with water. Much of Estherwood will be inundated due to backwater flooding from Bayou Plaquemine. Areas around Gueydan will be inundated with water due to backwater flooding from Bayou Que de Tortue. Communities of Klondike and Lowery will experience flooding as well.
• 9.5 ftWidespread major flooding will occur with residential flooding in and around mermentau to the lake arthur area. Numerous roads are inundated across a large area including u.S. 90, la 3166, la 1126, and la 92.
• 9 ftSome residential flooding in and around mermentau will occur. U.S. 90 west of mermentau is closed. Operations at the shipyards are affected. Roads in the mermentau cove area are flooded and impassable. Some residences are subject to flooding along the river near lake arthur.
• 8.5 ftSome residential flooding in mermentau will occur. Operations at Gulf Island shipyard can be affected. U.S. Highway 90 west of mermentau is flooded and subject to being closed.
• 6.2 ftThe water reaches the roadway of the 13th Street bridge in the southern portion of mermentau.
• 6 ftFlooding of the shipyard begins. Portions of castex landing, la 3166, become flooded and impassable.
• 5.5 ftA few recreational camps and residences are subject to flooding.
• 4 ftMinor lowland flooding near the river will occur.

Highest crests on record

1. 14.5 ft — August 7, 1940
2. 10.68 ft — August 18, 2016
3. 10.56 ft — January 15, 2013
4. 9.47 ft — December 10, 1972
5. 9.05 ft — April 25, 1977

Recent crests: 4.34 ft (October 1, 2022) · 7.48 ft (May 22, 2021) · 5.9 ft (October 15, 2020) · 5.46 ft (August 31, 2020) · 6.23 ft (May 14, 2019)

Up and down the river, and nearby

• UpstreamBayou Nezpique at Basile, LA
• Bayou Plaquemine Brule at Estherwood, LA
• Bayou Queue De Tortue at Riceville, LA
• Bayou Des Cannes west of Iota, LA
• Bayou Plaquemine Brule at Crowley, LA
• Bayou Mallet at HWY 91 north of Iota, LA
• Bayou Des Cannes near Eunice, LA
• Calcasieu River near Kinder, LA