Why It Matters
The U.S. Army Corps of Engineers is advancing a flood-control plan for northeastern South Dakota’s Waubay Lakes system that could trigger hundreds of millions of dollars in construction spending, yet the agency’s analysis relies heavily on precipitation patterns from only the past two decades—overlooking scientific evidence of extreme natural cycles spanning centuries.
What Happened
On June 30, the Army Corps of Engineers presented a study in Webster, South Dakota, outlining potential risks from rising water levels in the Waubay-Bitter Lake system. The report cited threats to roads, homes, farmland, and public infrastructure, with one scenario projecting nearly $100 million in damage.
The Corps’ analysis drew criticism from Jay Gilbertson, manager of the East Dakota Water Development District, who questioned why the presentation emphasized roughly two decades of precipitation data when earlier federal research had reconstructed the watershed’s climate history over centuries. Gilbertson’s concern points to a fundamental tension: the current study may be treating a temporary wet cycle as a permanent condition requiring massive infrastructure investment.
The Waubay-Bitter Lake system is a closed-basin watershed—meaning water does not naturally drain to downstream rivers—unlike comparable systems such as Devils Lake in North Dakota and Great Salt Lake in Utah. Following late-1990s floods, federal and state agencies commissioned five separate investigations into the 10-lake system, employing sophisticated paleoclimate methods.
Scientific Record Spanning Centuries
Earlier research by scientists employed dendrochronology—tree-ring analysis—to reconstruct the watershed’s hydrological history. Researchers drilled living bur oaks on islands within Waubay Lake and matched their rings with 19th-century bur oak timbers salvaged from Fort Sisseton, which soldiers had established in 1864. Historical Army records noted that the fort had initially been surrounded by a chain of lakes that largely dried in subsequent years.
The tree-ring chronologies revealed an extreme drought in the mid-1700s comparable in severity to the Dust Bowl. The analysis also documented dry periods during the Dust Bowl era itself and again during the 1976 drought—demonstrating that the Waubay Lakes have cyclically contracted and expanded over centuries without human intervention.
By the Numbers
27 years ago — timing of the Northern Great Plains Water Resources Research Center’s conclusion that the Waubay Lakes probably had not spilled naturally into the Big Sioux River since the glacial age
20 years — duration of precipitation data underlying the Corps’ current study projections
Nearly $100 million — potential public infrastructure damage cited in one Corps scenario
10 lakes — number in the Waubay-Bitter Lake system studied by federal and state agencies
$3 million — cost of the proposed general investigation feasibility study, with half to be paid by non-federal sponsors
Hundreds of millions of dollars — estimated range of construction alternatives under discussion
Zoom Out
The Waubay Lakes case reflects a broader pattern in water-resource planning: short-term precipitation trends can drive billion-dollar infrastructure decisions without adequate consideration of natural variability. Similar debates have surrounded Devils Lake in North Dakota and Great Salt Lake in Utah, both of which have experienced periods of expansion and contraction independent of human action. Policymakers nationwide increasingly face the challenge of distinguishing between cyclical fluctuation and permanent change when allocating federal and state funds.
What’s Next
The Army Corps’ Planning Assistance to States study is nearing completion. The next likely step is a $3 million general investigation feasibility study, with roughly half the cost borne by non-federal sponsors—typically state and local governments. If that study proceeds, it would lay groundwork for construction alternatives ranging into the hundreds of millions of dollars. State and local authorities will bear substantial financial responsibility, making the question of historical context increasingly urgent.