The Amazing Growing Lake

Devils Lake in North Dakota, a glacial depression which is slowly filling up with water:

The lake itself is not shocking. In fact, to eyes like mine, seeing it for the first time, it looks unremarkable, benign even—flat, blue, shallow around the edges. What's unnerving are the signs that the land beneath was dry not long ago. Every few miles along the highway, a cross-street leads straight into the blue, the yellow center lines almost beckoning drivers to follow and submerge. In the town of Minnewaukan, just past D Avenue, Main Street itself disappears into the water.

Around the corner, the playground in front of the local school awaits the water without defense. The football field across the street is already gone, transformed into a wetland with little mounds of grass where marsh birds nest. A wire cage still stands where the baseball diamond was, but on a Saturday afternoon in April, the only people near it are a man and a woman in rubber boots—fishing......

The problem is that it has not stopped. Unlike with a river flood, this water does not naturally recede after a week or a month. It has nowhere to go: The lakebed is the result of a glacier that melted roughly 10,000 years ago, and its only natural outlet is at 1,458 feet above sea level. Since August 1992, the lake has risen more than 29 feet. That would be a remarkable increase in nearly any body of water, but in the context of North Dakota's famously flat topography it is extraordinary; here, the rising lake spreads across the land like water spilled on a table. At the lake's current size, a one-foot rise consumes more than 15,000 acres of surrounding land. In 19 years it has grown from roughly 69 square miles to 285, an area about the size of Fort Worth, Texas.

In recent years the lake has become so massive that it has begun a sort of self-perpetuation through its influence on the local weather. The body of water adds so much moisture to the lower atmosphere that it may well be increasing the amount of precipitation the area receives. And on summer nights in Minnewaukan you hardly need the A/C anymore. Nice for sleeping, perhaps, but the cooler air means less evaporation, more standing lake.