Devils Lake is in northeastern North Dakota, near the geographic center of 
North America. Actually, Devils Lake is a series of connected lakes, carved 
by glaciers approximately 10,000 years ago, and covering about 100,000 
acres. Over the last seven years, Devils Lake has risen 25 feet! It has 
risen so much that there's a concern if the lake water rises another dozen 
feet, it'll cross its natural basin divide and flow overland into the 
Sheyenne River. This would result in severe flooding and pollution 
problems. Unlike hurricanes, tornadoes or flash floods, which can destroy a 
town in minutes, the high waters of Devils Lake is a slow-motion disaster. 
Thus far, an area greater than the lake itself has been flooded, and in 
places, the tops of telephone poles are protruding out of the lake. Uncle 
Sam has spent about $350 million moving homes, raising roads and building 
levees.

Through the years, the water level in Devils Lake has varied considerably. 
At the end of the great droughts in the 1930s, the elevation of Devils Lake 
(in October 1940) was 1,401 feet above sea level. This was its lowest level 
in recorded history - the average depth of the lake was only two feet! The 
lake level has dramatically increased since then, but in the late 1960s and 
the early 1990s, the water level again dropped in response to persistent 
periods of dry weather. In February 1993, the lake level was only 37% of 
what it was in 1987. Currently, the lake is 1,446 above sea level, which is 
higher that it has ever been since 1867, when records were first kept.

In the early 1990s, the fear was that Devils Lake might be drying up again. 
In fact, several dry years in succession had threatened the lake's famed 
walleye fishery. However, in a few short years things have completely 
changed. In the last seven years, above normal precipitation has caused the 
lake to overflow its banks. The three main precipitation events during this 
period were the exceptionally wet spring and summer of 1993, which affected 
much of the upper Mid West and northern and central Great Plains, the heavy 
spring snowfall in 1994 and the record snowy winter of 1996-1997. During 
the early part of 1994, the lake level increased 5 feet in 6 months! 
Although for the past three winters, snowfall has been much below normal, 
there has been adequate rainfall and groundwater to keep the lake full.

In regards to the Great Lakes, the level of water in the lakes during the 
last 15 years or so has not matched the water level in Devils Lake. From 
the late 1970s through the mid 1980s, a string of above normal snowfall and 
rainfall years in the Great Lakes region filled the lakes to record levels. 
For example, the maximum water level ever recorded for each of the Great 
Lakes , with the exception of Lake Ontario, occurred in 1986. In 1997, 
water levels were within inches of the 1986 records, however, much below 
normal snowfalls since 1998, droughts in some parts of the Great Lakes 
drainage in the summers of 1998 and 1999 and above normal temperatures 
(increased evaporation) have noticeably depleted the lakes' waters. 
Snowmelt runoff into the lakes is responsible for about 40% of the annual 
water supply of the Great Lakes. Additionally, because the past few winters 
were mild across the Great Lakes region, lake ice was minimal, and 
therefore evaporation was greater than normal. Between 1998 and 1999, the 
level of Lake Michigan fell about 20 inches, but the current water level in 
the Great Lakes is not unprecedented. The level of Lake Superior, for 
instance, is now approximately 601 feet, which is only about a foot lower 
than the 1918-1998 average and about a foot above the minimum level 
recorded in 1925.

Devils Lake is one of two large closed basins in the US - the largest such 
basin is the Great Salt Lake basin. Closed basins or terminal lakes have no 
outlets where their waters can drain naturally, thus they're like plugged 
tubs. So, the response to vagaries of weather and climate change is more 
immediate than it is for open drainage systems where water is constantly 
flowing from one drainage area to another. In general, the lag period is 
greater in open systems than closed systems in response to changes in 
precipitation patterns. With a large system like the Great Lakes, which 
receives water from eight states plus the Canadian province of Ontario, 
fluctuations in water input may not be seen in the lakes themselves for up 
to a year. Lake Ontario is the smallest of the Great Lakes, in terms of 
surface area, but it's still about 5 times larger than the entire Devils 
Lake drainage area. Obviously, a smaller basin will respond faster than 
will a larger basin when subjected to excess rain or droughts.

In terminal lakes, water is lost chiefly by evaporation. The process of 
evaporation causes dissolved minerals, such as salts and sulfates, to 
become more and more concentrated, and the lake's salinity increases. With 
prolonged periods of hot, dry weather, evaporation is maximized and water 
levels can quickly drop. On the other hand, when precipitation is abundant, 
the lake level will rise, and the level will continue to rise as long as 
precipitation exceeds evaporation. But even in closed basins, short term 
climate fluctuations don't always correspond directly with lake levels. For 
example, if an aquifer is in contact with the lake bed, as it is in Devils 
Lake, water can move from the lake to the aquifer or vice versa. Now, both 
the aquifer and Devils Lake are full, and it'll take more than a short dry 
period or sub normal snow season to make the lake level substantially lower.

Unlike rivers, which eventually deliver excess water to the oceans, when 
precipitation falls within the confines of the Devils Lake basin, much of 
it runs off directly into the Lake itself (some of it is evaporated and 
some enters the water table). Only rarely, though, will the "tub" overflow. 
If the next year or two are big snow and rain years in North Dakota, and 
Devils Lake reaches a level of 1,457 feet, it'll spill into the Sheyenne 
River, about five miles away as the crow flies. Climate records have 
indicated that this has only happened four times in the last 4,000 years. 
If you live along the Atlantic or Pacific coasts, flooding is something 
that goes with the territory, but if your home is near the exact center of 
the continent, it's hard to imagine that rising waters could force you to move.

For more about this see the Great Lakes Home Page:
http://huron.lre.usace.army.mil/levels/hmpglv.html 
Devils Lake, North Dakota home page http://www.devilslakend.com/  , The 
Washington Post for September 11, 1999 (A section), and the science 
question for April 1,1997.