Water Quality

Viewing a secchi disk as part of water quality monitoringLong-term water quality monitoring of the Squam Lakes contributes to our understanding of ecosystem health while promoting improved stewardship among watershed residents. Summer sampling on the Squam Lakes began in 1978 in cooperation with the University of New Hampshire’s Lakes Lay Monitoring Program; increased winter sampling began in 2017. Both programs provide valuable opportunities for ecological monitoring and continuing education throughout the Squam Lakes watershed.

Overall, the average summer seasonal water quality testing indicates that the Squam Lakes are well within the limits for a ‘pristine lake’ designation. However, certain areas of the lakes are displaying more productive conditions (more algae and weeds) during certain years, and some areas are approaching less pristine conditions at a faster rate than natural processes should dictate. A snapshot of annual conditions can be found in the 2018 Watershed Report, and a more comprehensive description of watershed conditions can be found in the 2019 Watershed Management Plan.

Get Involved!

The SLA’s rich history of water quality data is the result of decades of work by dedicated volunteers. The SLA relies on these volunteers to conduct water quality sampling throughout the year. Anyone can become a valuable part of our monitoring program! Current volunteers can find additional resources here.

Summer monitoring    (May-August)

Once per week, volunteers conduct water quality sampling at 16 sites across Big Squam and Little Squam (shown here). One measurement includes water transparency, or clarity, using a secchi disk. Though water clarity depths vary throughout the sampling season, secchi disk measurements of over 5 meters generally reflect pristine water quality. Algal blooms and suspended sediments are two factors that can impact water clarity. Every other week, volunteers also collect an integrated water sample. The sample is later tested for chlorophyll, phosphorus and color. Click here to learn more about becoming a Summer Water Quality Monitoring Volunteer!

Winter monitoring      (January-April)

Twice per month, LRCC members lead water quality sampling at 11 sites across Big Squam and Little Squam (shown here). This is the newest monitoring program, so motivated volunteers are desired! Measurements include dissolved oxygen, conductance and temperature and an integrated water sample. The sample is later tested for chlorophyll, phosphorus and color.

Email SLA at info@squamlakes.org about volunteering or questions about water quality on Squam.


Learn more

Water Quality Monitor Position Description

Learn more about the Squam through this basic limnology information sheet.

Yearly analysis of water quality in the Squam Lakes in the Squam Watershed Report

2013 Water Quality Reports from UNH

2012 Water Quality Report from UNH

1975 Water Quality study from Harvard University


Map of Squam water monitoring sites