Lake Water Quality

Ecology has monitored rivers and streams since before 1959 and, thanks largely to federal grants, we were able to monitor lakes from 1989 through 1999. During that period, we collected data from more than 180 lakes, with help from about 250 volunteers. In 2000, we were unable to obtain funding and we had to discontinue active management, though we continued to support the volunteer monitoring portion of the program for one last year. There is a brief description of the achievements and funding history of the lake monitoring program at this link. At present, there is no state-wide monitoring or assessment of lake water quality in Washington.

The Lake Water Quality Assessment Program

In 1989, the Department of Ecology received a grant from the federal Clean Lakes Program to monitor lakes in Washington. From 1989 through 1997 we typically monitored about 60 lakes annually, depending on the availability of volunteers. Ecology staff visited each lake in the spring or early summer and again in late summer while volunteers collected data every two weeks.

Parameters sampled included temperature, pH, conductivity, and dissolved oxygen profiles, chlorophyll, total nitrogen and total phosphorus. At selected lakes we also monitored hardness, turbidity, total suspended solids, and fecal coliform bacteria. Volunteers monitored surface temperature and Secchi disk depth and provided general information and observations about their lake. Volunteers also kept an eye out for Eurasian milfoil and zebra mussels.

To Get The Data: To get the data for individual lakes monitored in 1994 through 1997, find the lake of interest in this table, which lists all lakes and years monitored, with links to those data available on-line. Data collected prior to 1994, volunteer data collected since 1997, and annual reports are available from Maggie Bell-McKinnon (; phone (360) 407-6124). All reports (including associated data) are also available online in pdf format.

Lake-Specific Studies

In 1998, the Department of Ecology revised regulations regarding lake water quality. Lakes are unique water bodies--chemical, physical, and biological properties are lake-specific. Current regulations allow for standards based on geographic regions called ecoregions or standards may be determined for individual lakes. In 1998, we modified our program to try to address these regulations. Our goal was to propose water quality criteria (generally a phosphorus criterion) for each of twenty lakes annually.

In 1998 and 1999, instead of collecting the parameters listed above at all lakes twice a year, we conducted more intensive sampling at about 20 lakes each year. We collected chemical samples and measurements monthly during four summer months and added assessments of certain biological, habitat, and watershed characteristics. In addition, a public survey was distributed to assess, among other things, uses of the lake. Each lake was assessed, in part, on the quality of the water as it related to uses such as swimming, fishing, aesthetics, etc.

To Get The Data: Data and recommendations for individual lakes where we conducted lake-specific studies are available in PDF format. Reports (including associated data) are also available online in pdf format.

Other information about Washington's lakes:

Additional information about our lakes are available on these Ecology pages:

Other sites with information about lakes: