groundwater sample sites at Lake Spokane.  Picture courtesy of USGS.

Spring 2015 USGS ground water well sampling locations upstream,
 along, and just downstream from the Suncrest Community.

Water Quality Monitoring on Lake Spokane at Suncrest


Lake Spokane nutrient study at Suncrest

The United States Geological Survey (USGS) partnered with Ecology and students and faculty from Eastern Washington University to study the groundwater and aquatic plants upstream, along, and downstream of the Suncrest community in Stevens County. The purpose of the study was to determine if on-site septic systems contribute nutrients to Lake Spokane.

A USGS report, titled “Preliminary characterization of nitrogen and phosphorus in groundwater discharging to Lake Spokane, northeastern Washington, using stable nitrogen isotopes” is available on the USGS website.

The results show:

Update The Spokane River Forum, the Stevens County Conservation District, and Ecology are hosting a public meeting on May 24, 2016 from 6 to 8 pm at the Lakeside Middle School (map). At this meeting, Andrew Gendaszek from the USGS will present the study results and answer questions. Other Lake Spokane water quality topics will also be presented.

What happens next?

The study results show phosphorus and nitrogen make it to the lake, but we do not know how much enters the lake and if the concentrations and amounts change throughout the year. In addition, the results show there may be a nutrient source downstream of Tum Tum. The Stevens County Conservation District is partnering with the USGS on an additional study to learn more about nutrients in groundwater entering the lake. If you would like to know more about this additional study contact the Stevens County Conservation District at 509-685-0937 ext 3, or email Charlie Kessler at

Study Information

Scientists looked at nitrogen content in groundwater and aquatic plants along the shoreline near existing homes then compared them to samples taken from areas without homes. Scientists gathered data from:

Nitrogen from on-site septic systems has a unique chemical signature that can be detected in groundwater and plant tissue. Finding this type of nitrogen in plants and groundwater indicates that on-site septic systems are contributing nutrients through groundwater to the lake.

Too many nutrients like nitrogen and phosphorus in the Spokane River and Lake Spokane deplete dissolved oxygen that fish and other aquatic life need to survive. Excess nutrients can also cause toxic algae blooms that are harmful to human and animal health.

Study timeline


Timeline for the Lake Spokane Water Quality Monitoring at Suncrest study


Focusing on Suncrest

Studying the lake near the Suncrest community to determine if there is a nutrient contribution is part of a larger plan to improve the lake’s health. The Spokane River dissolved oxygen water quality improvement plan requires reducing all sources of nutrients like phosphorus and nitrogen from a variety of sources.

This study builds on a broader study conducted by Spokane County, which recommends further investigation of densely populated areas that rely on on-site septic systems for wastewater treatment.

The Suncrest community is the most densely populated cluster of on-site septic systems along the lake, with more than 1,300.

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Karin Baldwin

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Last updated May 2016