Monitoring Lakes by Satellite

Ground Truthing Landsat Satellite Images with Secchi Readings

Landsat 8 Overpass Dates for 2019

Path 12  Path 11 Path 10
Western Path Central Path Extreme Downeast Path 
5/19/2019 5/12/2019 5/21/2019
6/4/2019 5/28/2019 6/6/2019
6/20/2019 6/13/2019 6/22/2019
7/6/2019 6/29/2019 7/8/2019
7/22/2019 7/15/2019 7/24/2019
8/7/2019 7/31/2019 8/9/2019
8/23/2019 8/16/2019 8/25/2019
9/8/2019 9/1/2019 9/10/2019
9/24/2019 9/17/2019 9/26/2019
10/10/2019 10/3/2019 10/12/2019
10/26/2019 10/19/2019 10/28/2019
11/11/2019 11/4/2019 11/13/2019

Ideally, lakes are sampled within 1 day of satellite overpass, but usually data collected within 3 days are acceptable.  Please opt for the day with least cloud-cover.

Please consult the map below to determine if your lake is on Path 12, 11 or Path 10.  Please note that in some areas of the state there is overlapping of paths, so people can choose the most cloudless day given weather forecasts.

To view some of the previously collected  data, please consult this list in PDF format.
Lakes are listed in numerical order, according to the lake’s MIDAS number.
Path 12 lakes begin on page 26.  Please note:  this list is not comprehensive.

The efforts of volunteers to collect Secchi data matching flyover dates of the Landsat 8 satellite is paying off, according to DEP Biologist Linda Bacon. This technology has the potential to be able to identify algae blooms from space! Bacon says that “volunteer data will be more valuable than ever to help calibrate the satellite.”

As the Landsat 8 satellite orbits the earth it takes photos of Maine lakes and ponds (as well as other features of the earth’s surface). The satellite images could be used to help characterize the transparency for many Maine lakes (thousands!) for which we do not have current water quality data. Volunteer lake monitors can play an important role in helping to “ground truth”, or calibrate the satellite images by taking Secchi disk transparency readings on the days when the satellite passes over Maine.

Our Mission

The Mission of the Lake Stewards of Maine (LSM) is to help protect Maine lakes through widespread citizen participation in the gathering and dissemination of credible scientific information pertaining to lake health. LSM trains, certifies and provides technical support to hundreds of volunteers who monitor a wide range of indicators of water quality, assess watershed health and function, and screen lakes for invasive aquatic plants and animals. In addition to being the primary source of lake data in the State of Maine, LSM volunteers benefit their local lakes by playing key stewardship and leadership roles in their communities.


LSM is a non-profit 501(c)(3) organization committed to the collection of information pertaining to lake water quality. For 40 years, trained volunteers throughout Maine have donated their time so that we may all learn more about one of Maine’s most beautiful and important resources — our lakes.