Feature Article July 18, 2001
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The problem with water quality is us - Part II
by Gray Merriam, professional ecologist, and Aileen Merriam, Kennebec Lake StewardBodies of water receiving too much nutrient become eutrophic which just means overfed. Being overfed first changes the kinds of plants that grow in the water, then the little organisms that are the food for the small fish, and this in turn changes what kind of game fishes will live there. When overfeeding is really serious, some types of algae can take over from all the other plants, growing so much that they produce a layer of dead plants on the bottom. These dead plants decay, using up most of the oxygen that is dissolved in the water. Sometimes, when water is severely overfed, many fish die from lack of oxygen.
Reversing the overfeeding of a lake or river is very difficult and often impossible. Once so many nutrients are in a body of water, they tend to get recycled and stay there. Reducing the inflow does not reverse the changes, so dont let your lake slip into the overfed category. Encourage your neighbours to look after, and if necessary, rebuild their septic systems.
What else adds nutrients to the water and lowers its quality? The second most important cause of nutrient inflow is dumping fill and disturbing soil near water. The real problem here is soil with no plants growing in it. Plant stems and leaves slow down flow of water over the surface. Plant roots stop soil from washing into the water and also take up water containing dissolved nutrients. The plants keep the nutrients and evaporate the water through their leaves. Both nutrient inflow and soil erosion are prevented. All shorelines should have a strip of heavy plant cover to do these jobs for our water. We also should try to prevent denuding of road margins along ditches and lake shores and creek banks. Denuded or disturbed soil should not be along any waterways, however small.
Nor should lawns be along waterways or lakeshores. Whether fertilized or not, lawns let much more of the rainfall run off directly into the lake instead of soaking into the ground as it does in the leaf litter under more natural vegetation. Fertilized lawns add even more nutrients; phosphorus fertilizer runs off and nitrogen fertilizer dissolves in rain, soaks down through the soil and then enters the lake or river. Lawns should be separated from shorelines by a strip of vegetation which is allowed to accumulate leaf litter on the ground and has a dense root mass.
Cows in or near water also can contribute nutrients and possibly some other things to our waters. Industrial farming greatly increases the amount of nutrient which may be added to water. Even with high-tech liquid manure barns, if the liquid manure is sprayed onto the land, damaging amounts of nitrogen can be spread to surrounding waters. Nitrogen from sprayed liquid manure becomes volatile as ammonia in the air and can travel several kilometres before entering water and causing eutrophication. If crops do not take up all the manure quickly, even more nutrients will enter the waterways from the soil.
Where we live, water quality is one of our most important natural resources. Degrading water quality damages our living conditions and threatens the areas economic future. Low water quality is preventable; lets do it.
