Soil erosion
Soil erosion is the #1 source of pollution to surface water in Maine. Each year rainstorms and snowmelt wash tons of dirt off the land around Maine.
How could something so ‘natural’ be so bad? Soil erosion is natural after all. However, when we change the landscape from forest to yards, streets, farm fields, shopping centers and roads, we accelerate soil erosion.
- In the USA, soil is eroding at about seventeen times the rate at which it forms.
Erosion results in: (1) higher project costs, (2) damage to aquatic habitat, (3) reduced water quality, (4) elimination of trout and salmon fisheries, (5) lower shorefront property values, (6) higher property taxes, and (6) loss of business and jobs. Soil is a valuable resource on the land, but when washed into streams, lakes, and estuaries it is Maine's biggest water quality problem
We have all seen a stream in our neighborhood turn cloudy or brown after a rainstorm. This cloudy water makes it difficult for fish to see and feed properly. The particles act as sandpaper against a fish’s gills causing damage and making breathing difficult.
Many fish and aquatic insects lay their eggs in gravel beds. The sediments that are deposited in the stream cover up these areas, sometimes even entombing young fish and eggs.
The sediment may also destroy a stream’s natural ‘riffle and pool’ pattern and can make a stream shallower. When streams become wider and more shallow, flooding problems can increase. The shallow water is heated more efficiently by the sun, causing water temperatures to rise and then cold water fish, such as trout, are replaced by warm water fish.
Sediments cause problems for boating by increasing the chances of propellers, rudders and keels running aground or hitting underwater hazards. Swimmers are also affected. Silted swimming areas are undesirable and can be dangerous if deep holes are filled with loose sediment.
Sediments cloud the water and cover plant leaves, reducing sunlight penetration and inhibiting photosynthesis (plant food production). Sediment accumulations also harm duck populations by filling in their wetland habitats.
To add to all these problem, eroded soil particles are more than just soil particles. They carry hitchhiking pollutants like oil, fertilizers, pesticides and bacteria. Toxic materials can contaminate small organisms. When fish and waterfowl eat the contaminated organisms, the toxins accumulate in their bodies and cause illnesses, birth defects and death. In lakes, one particular hitchhiker can be devastating – phosphorous. With our changes to the landscape, we increase the amount of phosphorus running off the land. Phosphorus helps plants to grow, but in lakes it causes algal blooms, reducing water quality. (Picture of algal bloom in a lake; reports of algal blooms).
If you want Maine’s lakes to be blue, and the streams clear and healthy,
then we need your help.
We need you to help stop soil erosion.
The first step is to stop soil from moving in the first place. Keep soil undercover - covered by grass, shrubs and trees so the rain doesn’t have a chance to get at it and move it. Keep exposed areas on construction sites, driveways and parking areas to a minimum. And when areas must be exposed, mulch the areas every night, so that the soil is never left uncovered. Be sure to finish projects and seed the areas within 2 weeks.
If you can't keep the soil undercover, try to catch the soil before it reaches a stream or lake. If the volume of water isn’t great, divert the water running off driveways, roads and gardens into a stable vegetated area where the dirt can get trapped. The best idea is to plant a ribbon of trees and shrubs, referred to as a vegetated buffer, downslope of places like your home to capture soil and pollutants before they reach a stream or lake.
If you are not sure if there is any soil erosion happening in your neighborhood or aren’t sure where the worst sites are, try a rainy day survey. Go out during a rainstorm and look for brown water and trace it back to the soil erosion site. And it isn't just new projects -- you may find chronic sites where the ground has been eroding for years. Work with the local landowner by bringing the problem to his or her attention.
It may be one of our best-kept secrets, but the secret is out – soil is water quality enemy #1. Stop soil erosion for clean Maine waters.
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