Shadehill Reservoir Water Level
Shadehill Reservoir is at 2,264.95 ft today (Oct 31), 7.05 ft below its 2,272 ft full pool, down 0.19 ft this week.
South Dakota · Grand River
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Water level history
About Shadehill Reservoir
Shadehill Reservoir is a reservoir on the Grand River in South Dakota, operated by U.S. Bureau of Reclamation. Its full summer pool sits at 2272 ft above sea level. Live water levels come from the U.S. Army Corps of Engineers (CWMS) and update hourly.
Understanding Shadehill Reservoir's water level
Shadehill Dam sits on the Grand River about twelve miles south of Lemmon, just below the point where the North and South Forks meet, and it catches runoff from roughly 3,120 square miles of prairie. The Bureau of Reclamation built it as the Shadehill Unit of the Pick-Sloan Missouri Basin Program, authorized by the Flood Control Act of 1944. Work began on April 19, 1949, the reservoir first impounded water on July 1, 1950, and the dam was accepted as complete on August 15, 1951. Before it was finished, an April 1950 flood on the Grand River eroded part of the right abutment near the diversion channel. The reservoir would have flooded the Seim bridge, so the county moved it, and the Seim cemetery was relocated as well. Shadehill was meant to irrigate farms, but its water is high in sodium; a 1948 report put sodium near 75 percent with dissolved solids of 1,000 to 2,000 ppm, and Reclamation postponed the distribution works. In 1963 landowners voted 24 to 21 against forming an irrigation district, and today river maintenance releases cover what irrigation demand remains.
The number that matters is 2,272 feet. That is the top of the conservation pool, holding about 120,172 acre-feet, and it is also the crest of an ungated morning glory spillway, a 13.5 foot concrete conduit rated at 5,700 cubic feet per second. Everything above it, up to 2,302 feet, is flood space that drains on its own, with an unlined emergency spillway to Flat Creek behind that. Reclamation runs a steady winter release of about 50 cubic feet per second until ice clears the channel, to avoid ice jams at crossings, then fills the lake in spring, holds it near full through summer and positions it again in fall. The band from 2,260 to 2,272 feet was once flood storage and was returned to conservation use in 1972, but it is still drawn down somewhat ahead of spring runoff. Because the spillway is uncontrolled, a big March snowmelt shows up quickly as a rise above 2,272 and water pouring down the glory hole.
Shadehill swings with the prairie weather. The highest level on record is 2,297.90 feet on April 10, 1952, barely a year after completion. In March 2019, inflow peaked at 15,418 cubic feet per second, the lake reached 2,283.98 feet on March 29, and the spillway was passing about 4,000 cubic feet per second to the Grand River. In 2011 the Corps of Engineers had Reclamation hold Shadehill in fill and spill mode from June into August to relieve Missouri River flooding. The other extreme came in water year 2024, when evaporation outran inflow and net inflow for the year was negative, about minus 19,600 acre-feet. Several months set record lows for inflow in 73 years of data, and the lake slid to 2,263.03 feet by September 30, 2024. South Dakota Game, Fish and Parks manages the fishery and the Shadehill, Llewelyn Johns and Hugh Glass Lakeside areas. In its 2023 netting channel catfish were the most abundant species, while walleye were scarcer than average and were restocked with about 302,000 fingerlings and 389,000 fry.
Shadehill Reservoir — frequently asked
What is Shadehill Reservoir's full pool?
2,272 feet, the top of the conservation pool, where the lake holds about 120,172 acre-feet. The figure is also the crest of the ungated morning glory spillway, so any rise above 2,272 feet starts spilling to the Grand River on its own. Exclusive flood storage stretches above that to 2,302 feet, with another 230,004 acre-feet of room.
What is the record high at Shadehill Reservoir?
2,297.90 feet on April 10, 1952, with about 318,438 acre-feet in storage, about 26 feet over the spillway crest. The highest level in recent decades came in March 2019, when snowmelt pushed daily inflow to 15,418 cubic feet per second and the lake peaked at 2,283.98 feet on March 29. March 2019 inflow was the second highest for that month in 68 years of records. The gauge on this page only covers recent years, so the high it shows, about 2,271.9 feet in 2023, is a recent mark rather than the record.
Why is Shadehill Reservoir low?
Shadehill depends almost entirely on plains runoff from the Grand River forks, and in dry years evaporation can exceed what flows in. Water year 2024 was the clearest example: net inflow was negative, about minus 19,600 acre-feet, several months set record lows for inflow, and the lake dropped from 2,271.19 feet to 2,263.03 feet, nearly nine feet below full pool.
Why does Shadehill spill without anyone opening gates?
The service spillway is an uncontrolled morning glory, or glory hole, inlet with its crest at 2,272 feet, the top of the conservation pool. Water above that level drops into a 13.5 foot concrete conduit designed for 5,700 cubic feet per second. The gated outlet works add about 600 cubic feet per second. An unlined emergency spillway rated at 127,000 cubic feet per second discharges into Flat Creek.
Why isn't Shadehill water used for much irrigation?
Grand River water is high in sodium. A 1948 study found sodium near 75 percent and dissolved solids of 1,000 to 2,000 ppm, and test plots after 1951 showed exchangeable sodium building in irrigated soil. Reclamation postponed distribution works, landowners rejected an irrigation district 24 to 21 in 1963, and only about 3,064 acres were ever developed under contract. Current irrigation demand is met by river releases.
Where was the Hugh Glass monument at Shadehill?
Poet John Neihardt and rancher Otto Weinkauf placed a concrete obelisk honoring Hugh Glass in 1923, a century after Glass was mauled by a grizzly near the Grand River forks. It was later moved for the dam and stood on Reclamation land along the reservoir until October 2023, when the Neihardt family took it to Bancroft, Nebraska. A separate state marker from the 1960s remains.
How is the fishing at Shadehill Reservoir?
In Game, Fish and Parks netting in 2023, channel catfish dominated at 18.8 per gill net, with about 70 percent of adults over 16 inches. Walleye catch fell to 2.5 per net from 5.6 the year before, with fish from 7 to 23 inches, and the state stocked about 302,000 small fingerlings and 389,000 fry that year. Crappie were few but ran 10 to 13 inches.
Other lakes near Shadehill Reservoir
See current levels for all 6 South Dakota lakes and reservoirs →
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