The U.S. Geological Survey (USGS) and the jurisdictions in the Johnson Creek watershed are working together to provide hydrologic data for the Johnson Creek Basin. Real-time surface-water and ground-water data, and historic data and analyses, are critical to understanding the hydrology of the basin.
A cooperative study of the Johnson Creek basin was initiated in 1988 between the U.S. Geological Survey (USGS) and the City of Portland Bureau of Environmental Services. It was expanded in subsequent years to include Clackamas and Multnomah Counties and the cities of Gresham and Milwaukie. This multi-year data collection project continues to respond to the needs for hydrologic data and analyses, providing answers regarding surface-water, water quality, and ground-water in the basin.
Flooding in Johnson Creek results from direct surface runoff and increased ground-water discharge and poses problems in residential, commercial, and public areas. Commercial and residential development in the basin has likely affected both the high-flow and low-flow hydrologic conditions in the basin. Johnson Creek is one of the region's last free-flowing urban streams and has received Federal listing for native fish. Water-quality standards will be established by the Oregon Department of Environmental Quality over the next several years, and will result in Total Maximum Daily Load allocations for temperature, bacteria, and pesticides.
Further data collection and study in the future will help determine the effect of land use changes on the magnitude of streamflow and water quality.