American Scientist

Following severe drought in the American Midwest during the 1930s, North Dakota’s largest natural lake, Devils Lake, had nearly evaporated from the face of the Earth. Today, in response to climate change, the lake covers about 815 square kilometers and continues to expand, with devastating environmental effects.

Devils Lake is where I began my career as a limnologist in 1964, studying the lake’s neotenic salamanders and chironomids, or midge flies. Back then, the lake covered about 80 square kilometers, had a maximum depth of about 3 meters and held about 130,000 acre-feet of water. The lake has since risen 13 meters, from a surface elevation of 430 meters above mean sea level to 443 meters. Estimated lake volume is now 4.1 million acre-feet, or about 32 times greater than it was in 1964, and about 370 times greater than it was in 1940 when the lake stood at a record low elevation of 427 meters.

The Devils Lake Basin is an endorheic, or closed, basin covering about 9,800 square kilometers in northeastern North Dakota. The basin is at the epicenter of an unprecedented wet period in the lake’s modern-day history going back to 1867, when the lake’s surface elevation was first measured. Basin climate has become substantially wetter since 1990, with the years 1990 through 2009 ranking as the wettest 20-year period in more than a century. The National Weather Service has referred to this trend as “the new climate” for the Devils Lake region, cautiously predicting that the current weather pattern may continue for several decades and possibly intensify. Indeed, the agency has warned that the region faces the strong possibility of an “unprecedented fourth consecutive major spring flood threat in 2012.”

Rising lake waters have flooded much of the region, engulfing hundreds of homes and farmsteads, more than 650 square kilometers of productive farmland, major highways and bridges, state parks, Native American tribal lands, historical landmarks and more than half a million trees. Submerged too is the North Dakota Biological Station, a two-story limnological facility established in 1909 to study the lake’s unusual ecology and biogeochemistry. Portions of U.S. Highway 281 are now underwater, which has forced the relocation of this principal north-south highway several kilometers to the west. Other roads and highways are either extremely hazardous or simply impassable because of encroaching floodwaters. Amtrak and the BNSF Railway may have to reroute their trains over more southern lines as rising waters threaten to wash out roadbeds and bridges. The small town of Minnewaukan, once located 13 kilometers west of the lake, is now partly underwater, and many of its 300-plus residents have been forced to abandon their homes. Only a handful of people remain in Churchs Ferry and nearby Penn, communities established more than a century ago. The city of Devils Lake, North Dakota’s eleventh largest city with about 7,000 residents, sits behind a U.S. Army Corps of Engineers levee that protects the community from storm-generated waves that reportedly reach 2 meters or more in height. Without the levee, 3 to 4 meters of water would now cover parts of the city. To date, efforts by federal, state and local governments to control flooding and protect communities exceed $1 billion, a cost that is rising as fatefully as lake waters.

Ancient Lake Minnewaukan

Devils Lake owes its existence to a continental glacier that covered much of North America during the Pleistocene Epoch. Carving a basin as it advanced over the landscape, the glacier deposited excavated materials along its leading edges, leaving terminal moraines marking the farthest extent of glacial ice sheets. Near the end of the Pleistocene, roughly 11,000 years ago, the glacier began its retreat. As the glacier withdrew, glacial meltwaters poured into the basin, creating a vast proglacial lake dammed by morainal deposits. Native Americans called this lake Minnewaukan, meaning, among other possible interpretations, Bad Spirit Water. Recent flooding has perhaps given credence to a legend told by those Native Americans, claiming that the lake once overflowed and flooded the entire world.

Based on abandoned beaches, or strand lines, geologists estimate that the ancestral lake reached a maximum surface elevation of between 444 and 445 meters. At that elevation, the lake covered about 1,050 square kilometers, held about 5 million acre-feet of water and had a maximum depth of around 50 meters. A natural outlet called Tolna Coulee, which allowed water to flow out of the basin and prevented the lake from rising and expanding further, controlled the maximum elevation. How often the lake has overflowed is uncertain, but geologists believe it has happened at least twice over the past 4,000 years, most recently around 2,000 years ago.

During the centuries that followed the lake’s origin, climate shifts caused water levels to fluctuate between 6 and 12 meters every few hundred years. Sediment analyses by geologist Edward Callender, published in his 1968 University of North Dakota doctoral thesis, indicated that the lake might have been completely dry 6,500 years ago. After the lake last rose to its maximum elevation and began overflowing, water levels continued to fluctuate in response to alternating dry and wet periods. A persistently dry climate 500 to 600 years ago held levels at relatively low elevations for perhaps as long as 200 years. Wetter conditions followed, raising the lake to levels that prevailed until the late 1800s. Levels then began dropping precipitously, falling to the lowest-recorded elevation by 1940 before rising again.

Whether Lake Minnewaukan was completely dry at times or not, periodic drawdowns during dry conditions reduced its immense volume to numerous remnant lakes scattered across the south-central region of the basin. Nonindigenous people who settled the region beginning in the mid-1800s named the largest and most prominent of these remnants “Devils Lake,” perhaps because of the lake’s highly saline, undrinkable water, or perhaps in tribute to Sioux warriors whose canoes were often capsized in the lake’s treacherous, storm-tossed waters.

In 1964, Devils Lake consisted of three principal basins called West Bay, Main Bay and East Bay. West Bay then was essentially dry and Main Bay covered about 53 square kilometers. The Rock Island State Military Reservation separated East Bay—which covered about 27 square kilometers—from Main Bay. According to T. E. B. Pope of the U.S. Bureau of Fisheries, Main Bay and East Bay had become isolated during the 1890s after lake levels dropped about 6 meters during the previous 25 to 30 years. Besides Devils Lake, other major lakes nearby included Pelican Lake to the west and, to the east, East Devils Lake, Swan Lake, West Stump Lake and East Stump Lake, in that order.

Water Supply and Overflows

Devils Lake receives nearly all of its water from surface runoff and direct precipitation. Most surface-water runoff originates from a chain of remnant lakes located a few kilometers north of Devils Lake, although many of these smaller lakes have now merged with Devils Lake as the water levels rise. (By September 2007, for example, Devils Lake and all of the lakes to the east—including the two Stump lakes—had completely merged.) Total annual inflows ranged from near zero during the drought-stricken 1930s to nearly 400,000 acre-feet in 1993. Inflows, averaging 65,500 acre-feet annually between 1950 and 1993, rose to 317,000 acre-feet annually between 1993 and 2000, a fivefold increase. The years 1993 to 1995 contributed 24 percent of all inflow to Devils Lake between 1950 and 1995.

If Devils Lake rises approximately two additional meters and begins overflowing, as scientists predict it will, lake waters will enter the Sheyenne River. The Sheyenne, which originates 50 kilometers west of the river’s juncture with the Tolna Coulee outlet, meanders on an easterly course that lies about 15 kilometers south of the Devils Lake Basin. After turning south, the river is impounded by a Corps of Engineers dam (Bald Hill Dam) located 20 kilometers north of Valley City, a town of about 6,300 residents. The dam’s narrow reservoir (Lake Ashtabula) extends 43 kilometers upstream and contains about 71,000 acre-feet of water at full capacity. After passing through Valley City, the river joins the Red River of the North near the city of Fargo. The Red River flows northward before emptying into Canada’s Lake Winnipeg.

Like climate predictions in general, predictions about when the current lake will overflow are rife with uncertainty. For example, in a report published in 2008, the U.S. Geological Survey predicted that the probability of the lake exceeding 443 meters between years 2008 and 2015 was only 10 percent, but the lake reached that elevation in 2011. Also predicted was a 50-percent probability that the lake would not exceed an elevation of 442 meters between 2008 and 2040. In fact, the lake had reached 442 meters by June 2009. Recent computer simulations predict that the probability of the lake overflowing by 2030 is only 15 to 20 percent, even with planned man-made outlets in operation. That scenario may prove to be far too optimistic, however, given that precipitation totals during water year 2011 (October 1–September 30), which are forecast to continue, raised the lake 0.7 meters.

Hydrological Cycles and Chemistry

As a terminal lake lacking a natural outlet below an elevation of between 444 and 445 meters, Devils Lake loses water mostly to evaporation, which amounts to 86 percent of total inflow in 1986 and 73 percent in 1987. In 1988, evaporation loss exceeded total inflow by more than 200 percent, resulting in a net lake-water loss of about 100,000 acre-feet. During dry periods, lake-water salts became increasingly concentrated as lake volume diminished. Salinity was first measured in 1899 and reported thereafter as total dissolved solids (TDS). Lake volume between 1899 and 1920 decreased from about 520,000 to 272,000 acre-feet, doubling the TDS concentration from about 8,500 to 16,000 milligrams per liter (mg/L). After 1923, salinity was not measured again until 1948 when the U.S. Geological Survey obtained a TDS reading of 25,000 mg/L, the highest on record for the lake. Salinity was probably higher around 1940, however, when lake levels were the lowest on record.

Salinity has decreased significantly over the past 20 years in response to the extraordinary increase in lake volume. Although most of the remnant lakes have merged, salinities are not uniform throughout the lake system. An upward-trending salinity gradient extends southeast from Pelican Lake to East Stump Lake, a distance of nearly 80 kilometers. In 1949, the USGS recorded TDS concentrations of 2,300, 13,000, 41,000 and 106,000 mg/L along a transect beginning near Pelican Lake and ending at East Stump Lake. By 2010, after the lakes had completely merged, average TDS concentrations along the same transect ranged from 987 mg/L at the Pelican Lake site to 1,418 mg/L at Devils Lake’s Main Bay to 2,245 mg/L at the former East Stump Lake basin.

Sulfate is the predominant constituent of the lake’s total ion composition. In 1949, sulfate concentrations in Devils Lake’s Main Bay averaged 7,490 mg/L, representing 51 percent of TDS. By 2010, dilution had reduced the average concentration to 630 mg/L (range 610-651 mg/L), or 44 percent of TDS. Total sulfate levels are regulated by North Dakota’s Department of Health to protect municipal and domestic sources of drinking water. Sulfate will become an environmental issue when efforts get underway to pump water from the lake and discharge it through man-made outlets.

Garrison Diversion: A Relic

Devils Lake’s escalating salinity after 1899, coupled with shrinking water levels, ended what was once a prodigious commercial fishery. Between about 1880 and 1905, many thousands of northern pike, Esox lucius, were harvested annually and shipped by railroad to major midwestern and eastern cities. But even yellow perch, Perca flavescens, stocked in the lake as a replacement species, soon disappeared. By 1924, the lake’s only surviving fish species was the salt-tolerant brook stickleback, Culaea inconstans. Species diversity overall was greatly reduced, comprising largely organisms able to tolerate brackish waters.

Receding, increasingly saline waters had other unfortunate consequences. The Minnie H., a side-wheel steamer that carried passengers and freight between lakeside settlements and farms beginning in 1883, was retired in 1907 as shoals and other underwater hazards made steamboat travel ever more risky. Additionally, the shallow lake had become highly polluted with untreated sewage and agricultural wastes by the 1940s, allowing algae and macrophytes, aquatic plants, to proliferate. Decomposing plant material became a major source of recycled nutrients and rotting organic matter. Seemingly limitless swarms of emergent insects, principally midge flies, frequently drove lakeside residents and visitors indoors. The lake’s degraded, briny, foul-smelling condition gave it an unpleasant reputation as a body of water unfit for most aquatic life or for humans.

As part of the Congressional Flood Control Act of 1944, the Garrison Diversion Project called for diverting Missouri River water through a system of canals and intermittent canal reservoirs to irrigate drought-stricken farmlands in eastern North Dakota. The project included a permanent feeder canal into Devils Lake to “deepen, flush, and desalinate the lake for recreation.” Water diverted through the canal raised the lake from 427 meters, its lowest-recorded elevation, to 434.5 meters, which is marked as the “proposed level under Missouri diversion” in Figure 2. This would increase surface area from about 35 to 170 square kilometers, and volume from about 36,000 to 643,000 acre-feet. Assuming that 180,000 acre-feet of water with a TDS concentration of 800 mg/L or less was diverted to Devils Lake annually, the U.S. Geological Survey estimated that 10 to 12 years would be required to reduce the lake’s TDS concentration from 25,000 to 900 mg/L.

Garrison Diversion, scornfully called the “last of the Dust Bowl relics,” was extremely unpopular with environmentalists and the Canadian government. In 1973, Canada sent the U.S. State Department a diplomatic note requesting an “immediate stop” to Garrison’s construction. It declared that the project would violate the 1909 Boundary Waters Treaty by polluting rivers flowing into Canada, via the Red River and the Souris River, the latter located outside of the Devils Lake Basin. Despite formidable opposition, construction continued until the 1980s when the project was shelved due to funding and environmental constraints. Since then, nature has more than compensated for the project’s grand design for Devils Lake.

Flood Control

I returned to Devils Lake in 1975 to take aerial photos for an independent project tracking its limnological transformation. As the lake came into view, I was amazed at how large it had become since my previous visit in 1967. The lake had risen about 4 meters, doubling its surface area to about 175 square kilometers and increasing its volume fourfold to about 520,000 acre-feet. By the early 1980s, when the lake had risen another meter and covered nearly 200 square kilometers, concern was growing in the Devils Lake region about possible flooding. The Corps of Engineers, called on to help develop flood protection, proposed building a levee between the city of Devils Lake and the encroaching lake waters.

In 1984, the Corps constructed the levee, or “embankment,” as authorized under Section 205 of the Congressional Flood Control Act of 1948. The levee, consisting of gravel and clay overlain by boulders, was raised to a crest elevation of 440.5 meters, or about 5 meters above lake level. Subsequently, as the lake continued to rise, the Corps added to the levee’s height and length several times. Levee height was increased to a crest elevation of 442.1 meters in 1996, then to 444.2 meters in 1997 and finally to 445.1 meters in 2007, putting the crest elevation about 4 meters above lake level. Built in successive stages at a cost of $60 million, the levee at that point stretched for about 13 kilometers along the east, west and south sides of the city. Construction currently underway will raise crest elevation even farther, to 447.0 meters. Scheduled for completion this year, and costing $125 million, this fourth levee modification is intended to provide the city of Devils Lake with “full protection” from the lake’s overflow elevation of near 445 meters.

With levee construction underway, a plan was set in motion to build an “emergency” outlet to lower lake levels. The outlet, authorized by the North Dakota State Legislature in 2001, was essentially a channel that extended from Devils Lake near the westside town of Minnewaukan to the Sheyenne River, over a distance of about 23 kilometers. Completed in 2005 at a cost of about $30 million, the outlet was equipped with eight pumps to discharge lake water into the Sheyenne River at the rate of 100 cubic feet per second (cfs). Presumably, this relatively low discharge rate was established to prevent outflows from eroding the outlet channel and damaging the filtration system. The outlet, operated initially in August 2005, has since proved to be largely ineffective. After an 11-day trial run in 2005, the outlet was shut down for the rest of the year. In 2006, the outlet remained shut down due to high sulfate concentrations (600-800 mg/L) in discharge water that exceeded North Dakota’s water quality standard for sulfate (450 mg/L) in the Sheyenne River. In 2007, the outlet operated for 38 days, discharging only about 300 acre-feet of water. Between 2005 and 2009, the outlet removed approximately 30,000 acre-feet of lake water. Meanwhile, during the same period, the lake rose 0.75 meters, increasing lake volume by 855,000 acre-feet. In 2010, the outlet’s pumping capacity was increased to 250 cfs, which North Dakota’s State Water Commission claimed was still “insufficient.” Also in 2010, the U.S. Environmental Protection Agency relaxed the sulfate standard for the Sheyenne River, raising it to 750 mg/L to lessen or avoid water-quality violations when outlet pumps were operating. In 2011, because of pump failures possibly caused by sediment blockages, the outlet’s discharge rate was reduced to 125 cfs. Increased sedimentation may have resulted from the higher discharge rate authorized in 2010, which increased channel erosion. Between May and September 2011, the outlet had removed about 38,000 acre-feet of water, an amount that lowered the lake by an estimated 6 centimeters. Inflow to Devils Lake in 2011 totaled a record high of 595,000 acre-feet.

Three additional outlet facilities are either being planned or are presently under construction, all discharging from the lake’s east end. The first of these, the East End Outlet, is designed for a maximum discharge capacity of 350 cfs. Water will first be pumped through a buried conduit to the top of a rise, where it will then flow downhill through another buried conduit to the downstream reach of Tolna Coulee, a total distance of about 9 kilometers. The project is scheduled for completion this year at a cost of between $62 million and $90 million. Outlet number 2, the Emergency Gravity Water Transfer Channel, is a simple gravity-flow, open-channel outlet that will extend from the former West Stump Lake basin to Tolna Coulee, a distance of about 1.5 kilometers. This project, still in the planning stage and priced at about $17 million, will likely begin discharging water immediately. Discharge rates will increase to a maximum rate of about 670 cfs as the lake level approaches the natural overflow elevation of near 445 meters. Outlet number 3, the Tolna Coulee Control Structure, is designed to prevent catastrophic flooding downstream as Devils Lake begins to overflow. Functioning somewhat like a dam, this project will limit discharge rates to a maximum of 3,000 cfs during overflow. People living downstream of Devils Lake generally favor this outlet because of its flood-controlling capability, although there are some who insist that 3,000 cfs is still too much. (Flood stage at the town of Kindred, 45 river kilometers from the Sheyenne–Red River confluence, is about 3,200 cfs.) Upstream, the Devils Lake Basin Joint Water Resource Board initially opposed the outlet, claiming it would raise the lake approximately 1 meter above the natural overflow elevation. The board eventually withdrew its opposition, apparently after the Corps of Engineers provided absolute assurances that this would not happen. The project, scheduled for completion this year, will cost around $10 million.

From the beginning, the idea of discharging Devils Lake water into the Sheyenne River through manufactured outlets has been highly controversial. Opponents claim that outlets could introduce potentially harmful biota—pathogenic microorganisms, parasites and invasive species—and pollutants—agricultural pesticides, fertilizers and organic wastes—into the Sheyenne River and, ultimately, into Canadian waters via the Red River. Further, they argued, high sulfate concentrations would affect municipal water-treatment plants downstream. Worse, perhaps, outlet discharges could substantially increase the risk of flooding in the Sheyenne, Red River and Canadian watersheds.

The Canadian government, along with the State of Minnesota and nine other states that border the Great Lakes, led opposition to the westside outlet. All feared environmental damage to their waters. In a 2003 letter to various U.S. federal agencies, then U.S. Secretary of State Colin Powell discussed “unresolved environmental concerns” involving the U.S.-Canadian Boundary Waters Treaty of 1909 and the recently authorized Devils Lake outlet. Despite Powell’s concerns, and intensive lobbying and two legal challenges by opponents, the Bush administration and the U.S. Congress refused to kill the project. A nonbinding agreement eventually was negotiated between Canada and the U.S. to build the project, with Canada stipulating that the outlet be equipped with a technically advanced sand-filter to prevent harmful biota and pollutants from moving downstream. Although Canada agreed to pay the filter’s $25 million cost, North Dakota installed a less-sophisticated rock filter costing $50,000 instead, which prompted opponents to question its effectiveness.

In 2006, the Sierra Legal Defense Fund and other groups requested that the Commission for Environmental Cooperation—a watchdog organization created to monitor how well North American governments comply with environment laws—investigate the westside outlet, claiming it violated the 1909 Boundary Waters Treaty. The environmentalists cited Article IV of the treaty, which states that “boundary waters and waters flowing across the boundary shall not be polluted on either side to the injury of health or property of the other.” The commission dismissed the complaint on technical grounds, however, ruling that “it was not sufficiently clear that Article IV has the same force of law as a statute or regulation in either Canada or the United States.” Recently, in October 2011, the International Joint Commission, an independent advisory group established under the 1909 Boundary Waters Treaty, concluded after a three-year study that “the risk to downstream fish and fisheries from the parasites and pathogens of Devils Lake is low, and the potential for causing disease is minimal.”

A Thorny Dilemma

As Devils Lake approaches the size of Lake Minnewaukan, swamping human livelihoods and communities in the process, North Dakota’s Congressional delegation, its governor, and other public officials down to the level of city leaders and below find themselves on the horns of a dilemma. While thousands of people in the Devils Lake region have been gripped by an appropriate sense of desperation bordering on near-panic, their fellow North Dakotans living downstream of the lake in the Sheyenne and Red River valleys are also troubled. In a region already deluged by a wetter climate, the thought of augmenting record-breaking river flows with water discharged from Devils Lake is disturbing. Many undoubtedly remember the spring of 1997, when flood flows in the Red River essentially wiped out the city of Grand Forks, North Dakota’s third-largest city of about 53,000 residents. With peak flows measured at 137,000 cfs, and the river’s stage exceeding 54 feet—26 feet above flood stage and 4 feet higher than the all-time record posted in 1897—the river burst through protective dikes and completely inundated the city, forcing nearly 50,000 people to evacuate. Seventy-five percent of the city’s homes and more than 300 businesses were flooded, many damaged beyond repair. Fires burned uncontrollably downtown, gutting three square blocks. Damages reached $3 billion.

People living downstream of Devils Lake seemingly have the advantage in terms of political clout. Their numbers total nearly 200,000, representing almost a third of the state’s population. Most reside in the major eastern communities of Valley City, West Fargo, Fargo and Grand Forks, the latter two the homes of North Dakota State University and the University of North Dakota, respectively. Yet, as someone who grew up in North Dakota, I have no doubt that “downstreamers” sympathize wholeheartedly with those being forced from their homes, farms and historic towns in the Devils Lake region.

In defending their position, outlet critics contend that roughly half of the wetlands in the Devils Lake Basin have been drained for agriculture over the past several decades. According to the U.S. Fish and Wildlife Service, the basin’s original wetlands totaled at least 162,000 hectares (16.6 percent of the basin area), although the time frame for “original” is uncertain. Approximately half of these remain. Vast wetlands once captured and absorbed much of the runoff water from spring snowmelt and heavy summer rainstorms. In a study of the basin’s wetland depressions, both drained and undrained, the U.S. Fish and Wildlife Service reported that the depressions had a maximum water-storage capacity of 657,000 acre-feet. Water-retention rates for 2-year and 100-year-frequency runoff events were 72 percent (116,000 acre-feet) and 41 percent (435,000 acre-feet), respectively. Outlet opponents believe that efforts should first be made to restore wetlands and plug their drainages instead of building outlets. Studies indicate that restoring 60,000 acres of drained wetlands could provide storage volumes of between 156,000 and 294,000 acre-feet. But restoring wetlands could take years, probably decades to achieve. In any case, one outlet is already operating and construction of others is underway.

But what would happen if no outlets were built and the lake began overflowing through Tolna Coulee, its natural outlet? By then, the expanded lake would have consumed an additional 300 square kilometers of lakeside property, further submerging homes, farms, towns and infrastructure. For those downstream, the U.S. Geological Survey has painted an even more ominous picture: Great torrents of escaping lake water would erode the coulee floor down to elevation 441 meters—2 meters lower than the lake’s current surface elevation—releasing up to 2 million acre-feet of water uncontrollably—or about 40 percent of the lake’s entire volume. Like a tsunami, outflows of between 12,000 and 16,000 cfs would thunder down the Sheyenne River Valley for days, possibly washing out Baldhill Dam, and drowning towns and farms en route to the Red River Valley and Canada.

With the crisis unfolding, nature appears to have the upper hand, at least for now. Humans, seeking a technical fix at this late hour, may have lost control of their environment, a lesson about the importance of preemptive action to forestall or reverse an impending environmental disaster. This may be particularly true now that unpredictable climate change appears likely across the globe. Having lost the proactive advantage, those working to solve the problem at Devils Lake have been reduced to a rearguard strategy. That is a position that may become familiar to people around the world in years to come.