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Lake Tips: Valuable Resources
Think of a Lake You Visit
Lakes are significant to plants, wildlife and people. Lakes are critical because they provide habitat for fish spawning and growth. Plants that grow in and around lakes provide a source of food for many animals and nesting sites for birds. These plants also act as natural filters for nutrients and sediments, and stabilize the lake shore to prevent erosion.
Lakes also have economic, recreational and aesthetic value. Lakes provide flood protection, as well as water for drinking, irrigating agricultural crops, navigation, and the power to generate electricity. The quality that lakes add to everyday life is immeasurable. What other experience could be as peaceful as an early morning spent on a high mountain lake, or as joyful as a family gathering in the summer on a lake shore? Preserving and protecting lakes NOW is paramount for future generations to use and enjoy the lakes.
The Lake/Watershed Link
Because of the close connection between the lake and its watershed, the lake will be affected by the natural characteristics of the watershed and the human activities taking place there. Climate, soil, geography, the relative size of the lake compared to its watershed, the slope of the land, and how the land is used are all factors that will affect the quality of the lake.
For example, letís say you could identify the following characteristics of your watershed: several growing plants and grasses that provide vegetative covering for the land, a large lake with a comparatively small landscape (large lake-to-watershed ratio), soils that donít erode easily, gentle sloping land, and light rainfall. You might expect to find a higher quality lake in such a watershed. It would be higher quality compared to one that has a small lake surrounded by land that is stripped of trees and shrubs with highly erodible soils, steep slopes and heavy rainfall. However, things usually are not so obvious in the real world. Each lake and its watershed includes many variables that interact to either pollute or protect the quality of the lake.
The Lake Ecosystem
These processes, in addition to the lake and watershed relationship, will determine how much plant and animal life a lake will support. The biological productivity of a lake is referred to as the lakeís trophic condition or trophic status.
The trophic condition can range from least productive (oligatrophic) to moderately productive (eutrophic). Even without human input to a lake watershed, lakes will "age" naturally by becoming more productiveĖa process known as eutrophication. Human activity can speed up the aging process of a lake by tens or even hundreds of years. This human-induced, accelerated eutrophication is known as cultural eutrophication.
Threats to Lakes
What are the effects of pollutants from these sources? An overabundance of nutrients can cause algal blooms and excessive aquatic plant growth, and eventually can deplete oxygen supplies in lakes, causing fish kills. Organic wastes also can cause a lack of oxygen needed by fish for survival. Sediment loads from land erosion can fill in lakes and destroy habitats for plants and animals, as well as clog fish gills and smother fish eggs. Organic chemicals and metals such as mercury can contaminate fish and shellfish, making them unacceptable for humans to eat.
Copyright © 2005 North Dakota Department of Health