Industrial History: 1973 Rend Lake Dam on big Muddy River near Benton, IL

(Satellite, 295 photos)

This is one of those topics for which I can't believe I don't have any notes. So it is time to get them started.

USACE, St. Louis District posted two images with the comment:

Rend Dam is owned and operated by the St. Louis District and is located in Benton, Illinois on the Big Muddy River. Rend Dam creates Rend Lake, which helps reduce flood risk, supply water to nearby communities, provides habitats for fish and wildlife, and provides recreational opportunities. To learn more about Rend Dam and plan your visit, go to https://www.mvs.usace.army.mil/Miss.../Recreation/Rend-Lake/.
Rend Lake Project Office/ Visitor Center

The spillway in the photo is a small fraction of the length of the dam.

(Satellite)

Dale Stafford, May 2023

Like California, this dam was built for water supply. (Most big reservoir dams in the Midwest are funded for flood control.)

"For decades the land surrounding Rend Lake was plagued by lack of water - despite plentiful rainfall, and its location between two of the nation's great rivers, the Mississippi and Ohio....The land's impermeable clays were incapable of soaking in rain, making ground water scarce. By the 1950's the onset of an economically devastating three-year drought, took its toll on the region. As a result, plans to construct a large water supply lake began to take form, one that would be the solution to the area's problems, and evolve into the project that would become Rend Lake.... It supplies over 15 million gallons of water per day to 300,000 persons in over 60 communities." [USACE_history]

Dale Stafford, Sep 2022

I have not found a length for the spillway or dam, but judging from Google Maps, the dam is about 2 miles (3km) long, and the spillway is about 450' (140m) long. The spillway "notch" is about 30' (9m).

USACE_brochure

Given that the lake has reached a height of 413.83', I assume that 405' is the height of the bottom of the notch and 410' is the height of the top of the notch, which is the height of the main spillway. That means during the May 1995 flood, the water was almost 4' (1.2m) deep over the crest. That would have been getting kinda close to the top of the dam.