Mermentau River At Mermentau water level

Name: Mermentau River At Mermentau water level (U.S. Geological Survey)
Creator: U.S. Geological Survey
License: https://www.usgs.gov/information-policies-and-instructions/copyrights-and-credits

River gauge, Louisiana, United States

Directions

Normal for mid-October

Water level

1.94ft Steady over the last 24 hours

Measured Oct 19, 2026, 11:15 PM CDT (15 min ago)

Flow: 410 cfs

History

7 days

Water level Normal range (10–90 %) Forecast Minor flood stage

The forecast expects the river to rise to 2.10 ft by Tuesday, October 20 at 07:00 PM. Issued Monday, October 19 at 07:38 AM by NOAA National Weather Service.

What this means

The gauge at Mermentau River At Mermentau reads 1.94 ft, a normal level for mid-October.

The median for mid-October is 2.16 ft, based on 20 years of readings, so the river stage is 0.21 ft below typical. It is 2.06 ft below the flood stage of 4.00 ft.

It has barely moved over the past 24 hours. The forecast expects the river to rise to 2.10 ft by Tuesday, October 20 at 07:00 PM. Over the past 30 days it has moved between 1.41 ft and 2.11 ft.

Compared with 20 years of daily readings for this time of year. How to read levels

Key numbers

Median for this date: 2.16 ft0.21 ft below the median for this date
Normal for this date: 0.95 ft – 3.18 ft8 years in 10 fall in this range (20 years of records)
Highest on record: 14.50 ftAugust 7, 1940
Forecast peak: 2.10 ftTuesday, October 20 at 07:00 PM

What the stage means on the water

A normal level is usually prime time for floating and wade fishing, as long as the weather holds upstream.

The National Weather Service puts flood stage for this gauge at 4.00 ft, still 2.06 ft away.

What happens at each level

16.00 ft: Between 16 and 17 ft, flood waters reach the gauge over the mermentau river.
15.10 ft: Between 15.1 and 16.0 ft, flood waters reach the base of the southern pacific railroad bridge east of mermentau across an unnamed tributary.
14.30 ft: The river is at its flood of record. Widespread major to catastrophic flooding will occur.
13.40 ft: The river is near its 100 year flood level. Most of the community of mermentau is inundated with flood waters.
13.30 ft: Water reaches the roadway of the of U.S. 90 bridge east of Mermentau.
10.00 ft: Widespread 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.
9.50 ft: Widespread 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.
9.00 ft: Some 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.
8.50 ft: Some 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.
6.20 ft: The water reaches the roadway of the 13th Street bridge in the southern portion of mermentau.
6.00 ft: Flooding of the shipyard begins. Portions of castex landing, la 3166, become flooded and impassable.
5.50 ft: A few recreational camps and residences are subject to flooding.
1.94 ft: Right now

Impact statements from the U.S. National Weather Service.

Highest crests on record

Chance of at least minor flooding in October to December: 9 %.

Rank	Level	Date
1	14.50 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
6	8.96 ft	May 18, 2004
7	8.66 ft	June 2, 1941
8	8.61 ft	May 6, 2017
9	8.56 ft	May 20, 1980
10	8.54 ft	April 18, 1967

Weather at the gauge

The forecast is not available right now.

Sunrise 07:16 AM Sunset 06:35 PM Daylight 11 hr, 19 min First quarter 65%

Map

Nearby gauges

Gauge	Level	Compared with normal	24 hours	Distance
Bayou Plaquemine Brule @ EsterwoodRiver gauge	7.51 ft	Below flood stage	+0.05 ft	8 mi
Bayou Queue De Tortue @ RicevilleRiver gauge	4.72 ft	Below flood stage	±0	9 mi
Bayou Des Cannes west of IotaRiver gauge	11.16 ft	Below flood stage	−0.01 ft	10 mi
Bayou Mallet at Hwy 91 north of IotaRiver gauge, Bayou Mallet	1.75 ft	Very low	−0.07 ft	15 mi
Bayou Lacassine near Lake ArthurRiver gauge, Bayou Lacassine	10.09 ft	Very high	+0.06 ft	19 mi
Bayou Nezpique near BasileRiver gauge, Bayou Nezpique	1.73 ft	Low	−0.01 ft	20 mi
Bayou Des Cannes near EuniceRiver gauge, Bayou Des Cannes	0.08 ft	Very low	−0.01 ft	21 mi
Calcasieu River near KinderRiver gauge, Calcasieu River	1.49 ft	Very low	−0.12 ft	29 mi

Questions and answers

What is flood stage for Mermentau River At Mermentau?

The official flood stage is 4.00 ft. The level is currently 2.06 ft below it.

What is a normal level for Mermentau River At Mermentau in mid-October?

The median for mid-October is 2.16 ft. In 8 years out of 10 the reading falls between 0.95 ft and 3.18 ft, based on 20 years of records.

Is gage height the same as water depth?

No. Gage height is measured from a fixed reference point chosen by the agency, so a reading of 10 ft does not mean the river is 10 ft deep.

What is the water level of Mermentau River At Mermentau today?

On Oct 19, 2026, 11:15 PM CDT, the water level was 1.94 ft. Steady over the last 24 hours.

Is Mermentau River At Mermentau rising or falling?

Steady over the last 24 hours.

Is the level of Mermentau River At Mermentau normal?

Normal for mid-October. Compared with 20 years of daily readings for this time of year.

What is the highest water level ever recorded at Mermentau River At Mermentau?

The highest level on record is 14.50 ft on August 7, 1940.

For specialists

Station codes, datum, parameters, data quality and downloads

Operator: U.S. Geological Survey
Station code: usgs:08012150 (Agency page)
Coordinates: 30.19000, -92.59056 (WGS84)
Vertical datum: NAVD88
Update interval: every 15 minutes
Licence: Public domain. Data: U.S. Geological Survey (USGS), provisional data subject to revision

Published series

Parameter	Last value	Time (UTC)	Quality
Water level	1.94 ft	2026-10-20 04:15	Provisional
Flow	410 cfs	2026-10-20 04:15	Provisional

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How to cite

U.S. Geological Survey: Mermentau River At Mermentau (usgs:08012150). Accessed October 20, 2026 via Nivelmap, https://nivelmap.com/en/united-states/louisiana/mermentau-river-at-mermentau

How we check values

Each reading is stored as published. We hold back values that jump faster than physically plausible and show the measurement time with every value.

Readings are provisional, can be delayed or wrong and are not a flood warning. Read the disclaimer