The Lower Mississippi River Water Trail

St Louis

Historic Flood Crests

Historic Flood Crests from floods along the Lower Mississippi include:

(1) 49.58 ft on 08/01/1993

(2) 43.23 ft on 04/28/1973

(3) 42.00 ft on 04/01/1785 (P)

(4) 41.89 ft on 05/22/1995

(5) 41.32 ft on 06/27/1844

(6) 40.52 ft on 06/04/2013

(7) 40.30 ft on 07/02/1947

(8) 40.28 ft on 07/21/1951

(9) 39.27 ft on 12/07/1982

(10) 39.20 ft on 05/04/1983


Low Water Records

(1) -6.20 ft on 01/16/1940

(2) -5.80 ft on 01/26/1963

(3) -5.60 ft on 01/01/1964

(4) -5.50 ft on 12/12/1937

(5) -5.32 ft on 12/26/1989


Dredging might become necessary SLG 5.0 to -7.0

When the river drops below 4 on the SLG these levels, paddler beware: commercial barges may need to reduce tonnage, and dredging may be necessary to maintain a 9 foot deep channel for navigation. You may encounter dredges straddling the river in places you would normally find open free-flowing channels. Tows might by pulled up to the bank above and below sensitive locations (such as shoals) and work boats might be making waves as they speed back and forth between dredge and dormitory boats. For up to date channel conditions from the USACE-St. Louis District visit:


For more information go to USGS Water Data:

Go to the USGS Water Data site for more information about river flow (discharge in CFS), suspended sediment concentration in milligrams per liter, and suspended sediment discharge in tons per day, go to:


Using this gage you can compare some interesting periods of time in the river history, such as the recent high water - low water sequence in 2011-2012. At the end of April 2011 the river peaked near 35SLG, but by the end of Dec, 2012, it was below -4SLG, a difference of almost 40 feet! In the same time period the discharge went from around 600,000 CFS to below 60,000 CFS, a ten-fold change. The daily suspended sediment concentration went from near 2,000 milligrams per liter to around 25 milligrams per liter (which means from gravy thick muddy water to almost clear green tea-like water). The daily suspended sediment discharge dropped from 2.75 million tons of sediment per day down to around 5,000 tons of sediment per day.


The river at St. Louis has a drainage area of 697,000 square miles, which means everything upstream including the Missouri, the Upper Mississippi and the Illinois. This is a huge landmass, bigger than most European countries. Located at Latitude 38°37'44.4", Longitude 90°10'47.2" the St. Louis gage is 379.58 feet above sea level.


Middle Mississippi Start Place #1:

The Upper Mississippi


Maple Island Access Ramp, Melvin Price Lock & Dam, National Great Rivers Museum: Paddlers can start (or continue) their big river adventure by putting in at the last public ramp on the Upper Miss, the Maple Island Access Ramp. Fishermen flock to this area almost as thick as the white pelicans and bald eagles (in season) for the great fishing. Big fish get thrown up from the depths by the turbulence from the water flowing through the gates at the last Lock & Dam on the Upper Miss. Known affectionately by locals as “Mel Price,” this Dam is also the newest dam on the Upper Miss, with unique features like two lock chambers and a control tower that resembles one you might see at an airport. Guided tours available from the National Great Rivers Museum. Be sure to visit this museum (LBD Illinois shore). See below for description. For the Maple Island ramp and your short journey to the confluence, you can use the Melvin Price L&D gage. (Important Note: At the confluence switch to the St. Louis Gage. We’ll use the St. Louis gage for the Chain of Rocks, the St. Louis Harbor, and everything else downstream to Chester, and not make a switch until approaching the Chester gage).


Melvin Price L&D River Gage:


Low Water = 0 to 6 MPG

Medium Water = 7 to 15 MPG

High Water = 15 to 20 MPG

Flood Stage = 21 MPG and above

(MPG = Melvin Price Gage)


* Note: MPG 18 Near this height, Mel Price Lock and Dam will go to "open river" conditions, lifting all gates out of the river.


Water flowing around Maple Island according to Melvin Price L&D River Gage:

You can plan your route below the lock and dam and avoid all traffic by going behind Maple Island using the below table. In general, if the river is above 10MPG you can paddle behind all but the topmost island. If the river is above 12 MPG you will find all passages open, and you should be able to safely paddle anywhere around or behind islands. At flood stage 21 all but the tops end of all the islands will be underwater, and adventurous paddlers will find the best bird watching in the area by leaving the water channels and paddling directly into flooded forests. Not only a sublime entrance into the peaceful world of nature, but you will be able to witness life cycles and habits of birds no land birder would ever have the opportunity to view. (Note: Maple Island Ramp bottoms out in a bowl of mud below 8MPG.)


0 MPG No flow anywhere behind islands

6 MPG access begins to open up on 2nd (main) island, but you might scrape your vessel on rocks. Water slowly flowing through top notch only.

10 MPG - Gentle flow behind 2nd, 3rd & 4th Islands and below; safe paddling in most places, rocks still exposed on edges of all dikes

11 MPG topmost channel opens, wing dams and dikes starting to go completely under

12 MPG dikes completely under, slow flow top end, good flow elsewhere

13-17 MPG strong flow throughout, some minor boils & turbulence

18 MPG river bank full, watch for swirling eddies along entrances in between the islands

>21 MPG Flood Stage