The water drawn from the taps of two-thirds of Oregonian comes from our state's rivers, streams and lakes. The residents of Portland, Eugene, Sweet Home, Mill City, West Lynn, Baker City, Beaverton and a host of other communities across the state depend on surface waters for their drinking water.
Many of these public drinking water supplies come from watersheds located either completely or partly in federal forestlands. If these forests are intact, they play the role of natural reservoirs, absorbing, storing, filtering, and gradually releasing water to forest streams. This protects the purity of the water and consistency of its flows.
Logging, roadbuilding, and other development damages the forest's ability to produce clean water. In heavily logged forests, water runs off more quickly carrying with it soil and debris that can foul water filtration systems further downstream. The volume of runoff also increases, reducing the amount of water available during the dry summer months when water demand is higher and supplies are lower. Cutting trees also reduces the amount of water that an old-growth conifer forest gathers from fog. This source is significant--accounting for as much as one-third of all precipitation in Portland's Bull Run watershed. And once wide swaths of tree are cut, large land areas lose their shade cover, resulting in more evaporation from the soil, further reducing water flows.
And it becomes a bad deal for consumers. Not only is the quality of the water worse, but added treatment and filtration is required, increasing the costs.
Water from two of the state's watersheds, greater Portland's Bull Run and Baker City's Elkhorn's Front, doesn't require filtration and requires little treatment largely because it originates in protected watersheds.