All lakes ultimately exist through a delicate process of intake and outtake. If these systems become unbalanced – whether naturally or through human intervention – the result is the ultimate disappearance of that lake. This process is not too noticeable in a human timescale, as it happens over generations.
Oxbow lakes forms in river valleys and can be very susceptible to disappearance. Since oxbow lakes are the direct result of the flow of a river, meander rivers and streams can cause the reads and peat to intrude upon the edges of the lake. As these intrusions continue, the systems begin to form a wetland. As the wetland continues to dry, trees will intrude, sealing the fate of that area of the lake.
Irrigation is a prime example of human-initiated lake disappearance. Many lakes are fed by watershed and drainage systems. When these rivers and streams are diverted for agricultural purposes, they can affect lake systems thousands of miles away. Walker Lake in Nevada is an example of such an irrigation effect. The decreased water levels caused by upstream diversion have increased the salinity of the lake. The increased salinity can be toxic to fish and algae populations if it gets too high.
As global warming creeps into every aspect of our lives, researchers are beginning to find a connection between the disappearance of lakes and the thawing permafrost. As the permafrost levels decrease, these predominantly arctic lakes are beginning to drain into the newly thawed soil. In some instances, the rapid thawing also causes ages-old methane bubbles to release from the soil. These significant climate changes affect not only the lake, but the atmosphere and geography of the surrounding areas.
Lakes are an ecosystem of constant fluctuation. Their creation and continued existence rely upon the land surrounding them. Their purpose and existence are as varied as our individual experiences with them. The next time you’re out on a lake, stop to consider the incredible forces that brought these natural wonders to your senses.