Lake Water Quality

Portland Water District monitors the water quality of Sebago Lake and some of the major streams and rivers that flow into the lake.

The water quality of Sebago Lake is excellent and has been stable since PWD began its current lake monitoring program in the 1970s. PWD visits the deepest spot in each bay monthly from May to October.


Tributaries Monitoring Programs

PWD monitors chemical and physical characteristics of 11 of the major streams and rivers that flow into Sebago Lake. Monthly monitoring helps us keep an eye on conditions in the watershed and the quality of the water flowing into the lake. For more information, please see the Tributary Monitoring Report and the Crooked River Monitoring Report.

PWD annually monitors the aquatic insects in the Crooked, Northwest, and Muddy Rivers. This program gives us a good picture of the long-term health of the water in these rivers. For more information, please see the Biological Monitoring Report. (We do not have a report for the 2023 season because the high water levels in the rivers were unsafe for collecting samples.)

Lake Monitoring Programs

PWD monitors Sebago Lake the deepest parts of each bay of the lake – Jordan Bay, Big Bay, and Lower Bay. Physical, chemical, and biological parameters are monitored monthly from May through October.

For more information about PWD’s lake monitoring program please see the following reports:

Lake Monitoring Report

Lower Bay Bacteria Report


For real time water quality information, please visit the Sebago Lake Monitoring Buoy page.