Rend Lake Water Level
Rend Lake is at 403.12 ft today (Oct 31), 1.88 ft below its 405 ft full pool, down 0.21 ft this week.
Illinois · Big Muddy River
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Water level history
About Rend Lake
Rend Lake is a reservoir on the Big Muddy River in Illinois, operated by U.S. Army Corps of Engineers. Its full summer pool sits at 405 ft above sea level. Live water levels come from the U.S. Army Corps of Engineers (CWMS) and update hourly.
Understanding Rend Lake's water level
Rend Lake has no gates on top. The dam crosses the Big Muddy River 103.7 river miles above its mouth on the Mississippi, about three miles northwest of Benton, and its level is governed by fixed concrete. A notch 31 feet wide and 5 feet deep, with its crest at 405 feet, sets full pool: anything above that line spills into the Big Muddy on its own. Above the notch sits a 435 foot wide ogee spillway with a crest at 410 feet, the top of the flood control pool, and beyond that an 800 foot auxiliary spillway built as a dip in the highway over the east abutment at 415 feet. Below the notch the only releases are small flows through two 4 by 6 foot conduits, kept up to protect dissolved oxygen in the river downstream. That design explains most of what the gauge does. The Corps cannot pull the lake down ahead of a storm or hold water back in a drought, so the level simply rises with rain and falls with evaporation and water supply withdrawals.
Congress authorized the project in the Flood Control Act of October 23, 1962, as a lake for flood control, area redevelopment, water supply, fish and wildlife, and recreation. The St. Louis District started the subimpoundment dams in 1965, began the main dam in May 1968 and started filling on October 24, 1970. The main dam, an earthfill embankment 10,600 feet long and 54 feet high, was finished December 15, 1971, and the lake first reached normal pool on March 12, 1973. At about 19,000 acres the Corps calls it the second largest artificial lake in Illinois, yet it averages only 8 to 10 feet deep with a maximum of 35. It is also the main drinking water source for the Big Muddy region: the Illinois State Water Survey says the Rend Lake Conservancy District serves nearly 300,000 people across seven counties through 38 wholesale customers and more than 1,300 retail ones. On the shore, the 3,300 acre Wayne Fitzgerrell State Recreation Area, leased to the state by the Corps and dedicated in 1975, is named for the Sesser legislator who pushed for the lake.
Because nothing regulates the top of the pool, big rain years show up quickly. The Corps lists the record high as 413.83 feet, set in 1995. The April 2025 flood came close: the lake crested at 413.67 feet on April 6, 2025, the second highest level on record, and every boat ramp was closed along with the dam west shelter and parts of the Rend Lake bike trail. The gauge panel on this page covers only about 2020 onward, so its high of 413.12 feet in 2025 sits below both of those figures. Dry spells pull the lake the other way. In mid January 2026 it stood near 403.77 feet, which the Corps called near the top five lows, and a marina worker described the water as 6 to 8 feet below where it had nearly reached the parking lot the spring before, with boaters knocking propellers off late in the season. Those spring swings matter for fish too. A habitat grant summary notes that dramatically varying spring water levels make Rend poor for largemouth bass reproduction, so bass are stocked every year.
Rend Lake — frequently asked
What is Rend Lake's full pool level?
405 feet. That is the crest of the spillway notch and the top of the conservation pool, so any water above it flows out into the Big Muddy River without anyone opening a gate. The flood control pool runs from 405 up to 410 feet, the crest of the main ogee spillway, and the Corps lists about 302,000 acre-feet of storage at the top of that flood pool.
What is the record high at Rend Lake?
413.83 feet, set in 1995, according to the Corps. The closest challenger came in April 2025, when the lake crested at 413.67 feet on April 6, the second highest level ever recorded. At that crest all boat ramps were closed, along with the dam west shelter and sections of the bike trail. The page's own gauge panel starts around 2020, which is why its high reads lower at 413.12 feet.
Why is Rend Lake so low?
Usually because it has not rained enough. Rend has an uncontrolled spillway, so once the lake drops below the 405 foot notch the only water leaving is evaporation, water supply withdrawals and a small low flow release kept up for the river downstream. In January 2026 it fell to about 403.77 feet after a dry winter, close to the top five lows, and the Corps told boaters to stay near the deeper center of the lake.
Does the Corps draw Rend Lake down in winter?
No scheduled winter drawdown appears in the Corps records reviewed for this page. The St. Louis District's 1976 environmental statement describes normal pool held at 405 feet, so the annual rule curve is a straight line at that elevation. It adds that spring levels tend to run slightly higher than fall levels. Any drop below full pool comes from weather and water use, not from releases.
Who gets drinking water from Rend Lake?
The Rend Lake Conservancy District treats the water and sells it across southern Illinois. The Illinois State Water Survey calls the lake the largest drinking water source in the Big Muddy region, serving nearly 300,000 people in seven counties through 38 wholesale customers such as cities and water districts, plus more than 1,300 retail customers. Some of those wholesale buyers pass water on to towns outside the region.
When was Rend Lake built?
Congress authorized it in 1962. Work on the subimpoundment dams began in June 1965, the main dam was started in May 1968, and filling began on October 24, 1970. The Corps finished the main dam on December 15, 1971, and the lake reached normal pool for the first time on March 12, 1973. Wayne Fitzgerrell State Recreation Area on the shore was dedicated two years later, in 1975.
Is Rend Lake good for crappie?
It is the lake's signature fishery, though the big fish took management. A 4 pound 8 ounce black crappie caught there in 1977 set a state record, but by the early 2000s surveys showed few large fish. Illinois DNR added limits on April 1, 2002, and by 2009 biologist Mike Hooe reported a record number of crappie over 12 inches. Check current regulations before keeping fish.
Other lakes near Rend Lake
- Lake ShelbyvilleIL
- Carlyle LakeIL
- Lake BarkleyKY/TN
- Barren River LakeKY
- Blue Springs LakeMO
- Bull Shoals LakeAR/MO
See current levels for all 3 Illinois lakes and reservoirs →
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