Lake Oswego, Oregon – Storm Water Runoff

The Challenge
Municipal water quality managers recognize the need for data that can be used to monitor and assess the impact of urbanization to the condition of natural watersheds. Storm events in conjunction with the alteration of native landscape, the building of roads, and overuse of fertilizer can contribute excess nutrients, sediment, and other pollutants to environmentally-important watersheds. Such pollutants often make their way downstream through natural watersheds and detrimentally impact the water quality of fresh water bodies.

For the City of Lake Oswego, Oregon, quantifying the effects of watershed urbanization upon Oswego Lake – an important local fresh water reservoir – is instrumental for proving the future success of up-stream pollution prevention programs.

The major challenge for Lake Oswego was planning compact and unobtrusive water quality monitoring stations that leave a small footprint and have low impact to the surrounding natural environment. In addition, delivering data in a repeatable, low-cost way was deemed necessary for the long-term success of the monitoring program.

The Solution
David Gilbey, the City of Lake Oswego's Water Quality Program Coordinator, chose two local tributaries as initial sites for a Stream Discharge Gauging Network for the City's Supplemental Environmental Program. In part, this program is designed to characterize the effect of storm water runoff through two specific watersheds. The two tributaries chosen were Springbrook Creek and Lost Dog Creek, which most influence Oswego Lake.

Hach Environmental, headquartered in Loveland, Colorado, supplied the instruments for both water quality stations. Station instrumentation consisted of a Hydrolab MS5 Multi-Parameter Water Quality Instrument, an OTT CBS Compact Bubble Sensor (level meter), and an OTT LogoSens2 Station Manager (SDI-12 Logger). Each station measures and records pH, temperature, dissolved oxygen, specific conductance, turbidity, and water level.

Recorded data is regularly accessed from a local City of Lake Oswego office via a cellular-based Internet connection that connects the water quality stations to a PC. This setup not only provides instant access to real-time water quality data but also greatly eliminates the costs of routine travel to remote sites for data collection. Solar panels were installed to provide convenient year-round power without the addition of AC power.

The Result
Springbrook and Lost Dog Creeks are now being monitored continuously to better quantify any potential watershed impacts. Data collected from these sites can be used in near real time to calculate pollutant loading and review potential illicit discharges from upstream. Lessons learned from the implementation and monitoring of these sites will aid in the improvement of data gathering and expansion of the area's pollution prevention program.