|BMP's: Best Management Practices
In northern Idaho alone, at least 42 public water systems depend on surface water, collected from forested watersheds, for their main source of domestic water. Throughout Idaho, forest lands act as collectors of pure water. Protecting the source of pure water is the responsibility of both forest landowners and loggers. Best Management Practices (BMPs) are guidelines that should be used to direct forest activities and protect water quality.
Areas of land called watersheds (photo below left) collect precipitation and funnel it through a network of stream channels to an outlet at the bottom. Logging, road construction, and other forest activities can disturb soil, cause erosion, and release sediment into a watershed outlet.
Perennial and intermittent streams and ephemeral areas (e-fem-r-wl) are often found in forested watersheds (photo below right). Ephemeral areas drain water to intermittent stream channels. These carry the water to perennial streams, which flow to the watershed outlet. Any sediment created by soil erosion during logging or road building activities can be carried by way of ephemeral, intermittent, and perennial stream channels to the watershed outlet.
Ephemeral areas generally occur above the upper reaches of intermittent streams. Since they can direct water into intermittent stream channels, care should be taken to minimize disturbing soil in these areas.
Roads, skid trails, and landings can act as man-made streams carrying sediment when improperly planned, located, or constructed. If BMPs are not followed, sediment can make its way to the watershed outlet, creating problems downstream.
Wetlands found within a watershed include seeps, springs, wallows, marshes, and bogs. Some drain into streams, others do not. When forest activities occur in or around these areas, they should receive protection. Even when dry, they can be identified by the presence of certain plants.
Tree harvesting and other forest management activities can have minimal impacts to forested watersheds if conducted with careful regard to water quality. However, poor logging practices can cause excessive erosion (photo left). Tearing up the Topsoil on the forest floor destroys its filtering action, and compacting the soil affects surface water absorption. When surface water is allowed to flow into roads and trails, they become man-made streams that increase in speed and volume as they flow downstream. They tear away the soil, destroy roads, overload streams with sediment, and damage streambanks.
Excessive runoff and sedimentation into streams can increase filtering costs for drinking water, interfere with irrigation systems, and increase flood potential (photo right). Fish eggs laid in stream gravels become buried in sediment and suffocate. Removing shade from strearnsides can raise water temperatures, which affects fish and other aquatic life. Streamside damage also affects wildlife that rely on these habitats.
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