Devils Lake in northeastern North Dakota is a closed basin lake. Located at the lowest point within its basin, Devils Lake has no outlet. The result is that the lake is more prone to significant lake level variations. Lately, it has only been rising.
A USGS North Dakota Water Science Center graph shows the lake’s level has been higher in the past two decades than ever recorded.
A general trend of above average precipitation in the region has caused Devils Lake to rise rapidly over the last few decades. If the lake reaches 1,458 feet (444.4 meters) above mean sea level, it will naturally overflow into the Sheyenne River, a tributary of the Red River. The North Dakota Geological Survey has determined that the lake has probably overflowed into the Sheyenne River only twice in the last 4,000 years.
These Landsat images clearly show the lake’s dramatic change. In 1993, the lake water level was 1,422.6 feet (433.6 meters) above mean sea level. The lake reached an all-time high of 1,454.4 feet (443.3 meters) above mean sea level in June 2011. In 1993, the lake covered about 44,000 acres (17,800 hectares)—it has expanded to over 211,000 acres (85,400 hectares).
Even though it is still a few feet from its overflow level, the lake’s rapid rise is a great concern for residents of the region. If the lake does reach its overflow level, natural flooding could cause considerable damage downstream. The loss of farmland caused by the rising water has already been devastating to local farmers.
Another concern is algae blooms. The 2018 images show blue-green algae discoloring the water. In a severe algae bloom, the water can resemble spilled green paint or green pea soup.
East of Devils Lake is Stump Lake. It becomes part of Devils Lake at a water level of about 1,447 feet (441 meters) above mean sea level. By the 2011 image, a channel connects the two water bodies.
When Devils Lake reaches a level at which it overflows, 1,458 feet (444.4 meters) above mean sea level, water would spill from Stump Lake through Tolna Coulee into the Sheyenne River. The U.S. Army Corps of Engineers completed a control structure at Tolna Coulee in 2012.
The Tolna Coulee control structure is essentially a dam designed to prevent uncontrolled overflow from Stump Lake. An uncontrolled overflow could cause significant flooding damage downstream. Furthermore, water in Stump Lake has more sulfates than the water in western Devils Lake. Large volumes of water flowing uncontrolled through Tolna Coulee could cause water quality problems for communities downstream.
One flood mitigation plan might be to encourage excess water from Devils Lake to flow through its natural overflow point into the Sheyenne River before the level becomes too high. The problem with this idea is of water quality. As a closed basin lake, Devils Lake contains more sulfates than the Sheyenne River. Devils Lake water cannot simply be pumped into the river.
Because the majority of the water enters the west end of the lake, the amount of dissolved solids increases toward the east part of the lake. So even though the natural outflow point is in Stump Lake in the eastern portion of the basin, the state of North Dakota built an outlet on the west side.
This outlet can pump up to 250 cubic feet (7 cubic meters) per second into the river. It was built as an emergency outlet to mitigate the damage that could be caused by a natural spillover of the lake. However, when the Sheyenne River is high, the amount of water that can be pumped into it is limited.
Landsat imagery is one of many data sources used to help solve the problems caused by the rising levels of Devils Lake. Monitoring the changes caused by the rising waters can help mitigate damage to farmland, roads, and structures.
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