National Lakes Survey

The Department of Ecology sampled 30 Washington lakes during the summer of 2007 as part of a national lake water quality survey

Thirty Washington lakes were randomly chosen as part of a group of more than 900 lakes nationwide to examine and report on the ecological health, water quality, and recreational value of the Nation’s lakes.

The U.S. Environmental Protection Agency funded the National Lakes Survey, and in Washington, Department of Ecology staff conducted the water quality sampling, habitat assessments, and other data collection.

Goal of the program

The goal of the national lakes survey was to address two key questions about the quality of the Nation’s lakes, ponds, and reservoirs:

The lake survey used a probability-based sampling design which will provide statistically valid estimates of the condition of all lakes that share similar physical characteristics. Individual lake assessments were not a goal; the program was not designed to address conditions at particular lakes.

Where did we sample?

Nationally, more than 900 lakes—representing five size classes and distributed evenly across the lower 48 states—were included in the survey. The lakes were selected randomly and included natural and man-made freshwater lakes, ponds, and reservoirs that were at least 3.3 feet deep and over 10 acres in size. 

The thirty Washington lakes randomly selected for the survey ranged from 17-acre Lake Louise in Whatcom County to 7,600 acre Lake Ozette in the Olympic National Park. 

Water Quality Indicators

The following water quality indicators were sampled at each lake:

Trophic Indicators

Ecological Integrity Indicators

Recreational Indicators

The results

Data from the National Lakes Survey were compiled and analyzed by EPA and partnering agencies. The final national report is available at EPA’s National Lakes Assessment .

The Washington Department of Ecology wrote their own report analyzing the data collected from the thirty Washington lakes sampled as part of the national survey.  This report presents the statewide status of lakes in terms of good, fair, and poor condition as well as evaluating which are the most important environmental stressors affecting Washington lakes. The final state report is available at 

If you have any questions, please contact Maggie Bell-McKinnon.  

Additional information about the National Lakes Survey (external links)

Other sites with information about lakes

For more information about the National Lakes Survey and Washington's role, contact Maggie Bell-McKinnon (360-407-6124).