The Harmful Effects of Unpaved Roads being a Non-Point Source of Sediment Pollution

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Fugitive dust emanating from an unpaved road is widely known as being a costly nuisance. However, many people are not aware that the same small soil/aggregate particles responsible for the dust can also be a major source of stream sedimentation. This can be detrimental to adjacent trout and salmon streams.

When heavy rains occur and flow over an unpaved road, it can dislodge the finer particles on the surface along with additional fine particles that are “pumped’ up to the surface by traffic. In worse cases, heavy rains can deeply erode the surface and base of the roads. Sediment originating from unpaved roads can be considered as a non-source pollutant.

Sediment carried off the road and surface runoff can greatly affect the productivity of a trout or salmon stream. In a healthy stream, young trout and salmon use the interstitial spaces between cobbles and boulders to hide and avoid predators. This important cover can be destroyed when sedimentation fills in the spaces. In addition, the highly-oxygenated hiding place used by young trout is also extremely important for the survival of aquatic invertebrates such as stonefly, mayfly, and caddisfly nymphs. These invertebrates supply most of the food for the young salmonids. If fine sediment clogs the spaces between streambed gravel, juvenile salmonids lose their source of cover and food.

Also, adult salmonids are very susceptible to sediment pollution since their eggs are buried within the gravelly stream bottom. These spawning nests are known as redds, which require a steady flow of clean water to supply oxygen and remove waste products. It is important these nest sites remain sediment-free since when the eggs hatch into alevins, they remain in the gravel for a relatively long while before emerging upwards through the open space in the gravel to continue their life in the stream. It has been documented that as little as a 13% increase in fine sediments can eliminate the survival of the eggs in steelhead trout and Coho salmon redds.

These examples show how sedimentation can have a major effect on the survival of the eggs and alevin. The introduction of sediment in excess of the normal natural amounts can also have numerous other adverse effects on salmonids and their habitat. For example, low levels of sediment may result in sublethal and behavioral effects such as stress, increased activity, and emigration rates; loss or reduction of foraging capability; resistance to disease and reduced growth; physical abrasion; clogging of gills; and interference with orientation in homing and migration. As a result, sediment can be fatal at high levels.

So what can be done to minimize sediments from an unpaved road? A good practice is to use an environmentally-friendly dust control or base stabilization product that can efficiently and effectively bind soils and aggregates together and does not wash off with rainwater. With this in mind, Earthbind® 100 and Earthbind® Stabilizer are good choices. Earthbind® products not only can control fugitive dust, they can at the same time help mitigate stream sedimentation during the rainy season.

Give us a call at 1-800-536-2650 today to get the products and services you need to not only better your roads, but preserve the natural water systems and wildlife nearby. Let EnviRoad help you get to the places you need to be today!