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THE EFFECTS OF SOIL EROSION AND SEDIMENT DEPOSITION ON A WATER COURSE
The deposition of sediment into a waterway can significantly diminish the water quality and aquatic habitat. Sediment deposition in a waterway makes the water more turbid and does not allow as much light to penetrate the water. This causes problems for aquatic plants that need sunlight in order to perform photosynthesis. Furthermore, suspended sediments in the water have the potential of clogging the gills of aquatic organisms and covering the stream bottom. Deposition of sediment on the stream bottom can lead to the suffocation of fish eggs and benthic macro invertebrates and can cause the destruction of natural spawning substrate. Also, with an increased amount of particles in the water, dissolved oxygen levels are reduced because of higher water temperatures.
Pesticides, some metals and other toxins may sometimes cling to suspended sediments in water and increase the concentration of toxins in water with high amounts of suspended sediments. Similarly, phosphate can also enter a waterway by attaching to eroded particles. When in high levels, phosphate in the water can lead to algal blooms and lower the amount of dissolved oxygen in a waterway (NBDELG, 2000).
The main water quality and fish habitat issue facing the Mill Creek (excluding the presence of the dam) is bank erosion and sediment deposition in the creek. One site in particular that has been a cause for concern for the MCWG is where the NB Power transmission lines cross over the Mill Creek in two separate locations. The continual brush cutting and usage of all terrain vehicles along the transmission lines make these areas particularly susceptible to erosion. In the picture to the left you will notice that there is a large amount of sediment that enters the water during spring and periods of heavy precipitation (map).
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