INTRODUCTION
Montana, Idaho, Washington, and Oregon have experienced tremendous population growth in the
past 15 years, and this growth is expected to continue. To many people’s surprise, a great deal
of this growth is occurring in rural areas without centralized infrastructure, such as sewage treatment
plants. This rural growth tends to be concentrated near rivers and lakes, where increased wastewater
loads can threaten water quality. One of the biggest challenges facing state and local governments
is how to deal with the increase in wastewater while protecting the water quality that is crucial to the
natural beauty of these areas.