Field Notes: Three Weird Lakes

Jul 14, 2020

For this month’s Field Notes, Susan Knight of UW-Madison’s Trout Lake Station shares three stories about strange lakes from around the world.

I don’t need to tell you that we live in a lake-rich area, with some of the most beautiful lakes in the world. But as lovely as they all are in their own way, I wouldn’t call any of them weird.  There is Mary Lake in Winchester, which is meromictic, but that is a story for another day. Today’s topic is a trio of downright weird lakes. Two of these lakes are in the US, but the first one we will consider is Lake Nyos, in Cameroon.

For the geographically challenged like me, I will remind you that Cameroon is in western Africa, on the coast of the Atlantic, a little north of the equator. Lake Nyos is a crater lake in Cameroon about a mile wide, and 700’ deep. Lake Nyos was formed on the flank of a once-active volcano, when volcanic lava interacted explosively with groundwater about 12,000 years ago. Though the volcano is inactive now, the lake sits atop a pool of magma, and this magma is constantly releasing carbon dioxide into the water.  Like our deep lakes in the Northwoods, Lake Nyos is stratified with cooler water at the bottom and warmer water on top.  The cooler bottom water is saturated with carbon dioxide bubbling up from the magma. This cool, carbon dioxide-rich water usually stays at the bottom of the lake, with the pressure of the overlying warmer water acting like the cap on a bottle of Coke keeping the CO2-rich water safely at the bottom year round. But in 1986 something happened – maybe a landslide or a small earthquake – triggering the water at the bottom with all the dissolved CO2 to suddenly erupt up to the surface. Scientists estimate the event created a plume of water 300’ high, releasing a cubic kilometer of gas. The cloud of carbon dioxide spilled over the lip of the lake and poured down the valley, displacing all the air. Within minutes, the cloud of carbon dioxide asphyxiated 1,746 people, and 3500 livestock living within 16 miles of the lake. To make sure this catastrophe never happens again, tubes have been placed vertically in the lake to allow carbon dioxide from the bottom to harmlessly vent to the atmosphere.

The second story, about Lake Peigneur in Louisiana, is not as tragic, but it is strange. In November 1980, the lake was about 10’ deep and popular with anglers fishing for catfish.  There was a Diamond Crystal salt mine mining enormous salt domes more than a thousand feet under the lake. And where you find these salt domes, you often find oil.  So it was not surprising that while the salt was being mined from tunnels under the lake, an oil rig had started drilling a bore hole from near the lake edge.  In a serious miscalculation, the drill pierced the roof of the salt mine, 1300 feet below the surface. Once the drill punctured the roof of the mine, the salt miners could see water rushing into the cavern of the mine, and they quickly evacuated.  Water continued to rush in, expanding the hole and completely draining the lake.  11 barges, a tugboat, countless trees and a big chunk of nearby botanic garden disappeared into the growing maw. The vortex was so strong that a canal that usually drained the lake toward the Gulf of Mexico reversed course and flowed into the lake.  After a few days, the water pressure equalized, and – I really can’t believe this – they claim 9 of the barges popped back out of the hole and up to the surface. Thanks to frequent safety drills, all of the salt miners escaped. The lake is now salty, thanks to the backflow of the canal bringing Gulf of Mexico water into the lake, and the whole ecosystem has changed.

The last story is also about a disappearing lake, Mountain Lake in Virginia. Mountain Lake has a history of fluctuating water levels and is as much as 100’ deep when full. It relies on precipitation to fill, but occasional droughts cause water levels to stay low.  Adding to this problem, there are fissures in the bedrock underlying the lake and the lake fills or drains, depending on how clogged the fissures are.  The lake was looking more like its old self back in 1987, when it was the location for the movie Dirty Dancing, with Patrick Swayze and Jennifer Grey. Right now, the lake is not much more than a scuzzy puddle and the resort on the edge of the lake offers amenities other than water activities to entertain its guests.

I don’t know why all these weird stories came out of the 1980s. Let’s not take our wonderful lakes for granted, and let’s treat them with respect and care.