Water Quality Monitoring

A Water Quality Baseline Inventory of the park was initiated in September of 1995. Sites sampled in this inventory included the Lewis and Clark River, 2 permanent streams, 1 ephemeral stream, 2 ephemeral ponds and 1 slough.  All sites were sampled 3 times per month throughout the year. In the case of the ephemeral sites sampling ended when they dried up and began again in the fall when the water returned.

Water quality samples included readings and measurements for temperature, conductivity, salinity, turbidity, pH, alkalinity and dissolved oxygen. Stream flow measurements were taken in the streams and springs. Nutrient and ion analyses were performed by an outside contractor three times during the inventory period.

In November of 1998, the Baseline Inventory ended, and the Long-Term Monitoring Inventory began. The sites chosen for long term monitoring were based on results of the Baseline Survey. A sampling schedule was set up for each individual site with most of the sites being monitored every other month. Colewort Creek was added in 2006 after the South Slough property was included in the park. In February of 2020, the Yeon pond at the Sunset Beach Education Center was also added. This monitoring program is ongoing at the present time. Sites currently being monitored include the Lewis and Clark River, Skipanon River, Colewort Creek, Alder Creek, Megler Creek, the Historic Spring, Clay Pit Pond and the Yeon Pond.

Good water quality is crucial for salmon and other aquatic life. The North Coast and Cascades Network (NCCN) Inventory & Monitoring Program helps Lewis and Clark National Historical Park monitor the health of our rivers and streams. Learn more about this program and read about our findings on the NCCN Water Quality Monitoring Website.

In 2016, the North Coast Watershed Association began a temperature monitoring program to observe watersheds’ summertime high temperatures in their service area. Water temperature is an important factor for the health of all species in the watershed and a limiting factor for survival of salmon. Learn more about this program and review the temperature data on the North Coast Watershed Association Website.