Monitoring and Assessment of Lakes - Data

Much of the lake monitoring in the state is done to assess "trophic state" or the productivity of the water. Our 55+ year record includes data on over 1400 of our 5785 lakes, including parameters such as transparency, conductivity, alkalinity, total phosphorus and chlorophyll-a. The Maine lakes dataset is one of the most comprehensive lake data sets in the country.  Data is collected by DEP staff, volunteers working with Lake Stewards of Maine (LSM), regional organizations and institutions of higher learning.  Most of these data are available through the Lakes of Maine website.

DEP Lake Assessment monitoring includes annual late summer Baseline sampling, monitoring of lakes in Maine’s Ecological Reserves and other protected areas, long-term continuous monitoring of four reference lakes, and special projects.  Baseline sampling happens annually between August 1 and September 15, when lakes usually show their worst water quality.  We measure Secchi transparency, obtain temperature and dissolved oxygen profiles and collect samples for total phosphorus, chlorophyll-a, conductivity, alkalinity, true color, dissolved organic carbon, and a variety of cations and anions.  Examples of special projects include monitoring for MBTE, mercury, PFAS, plankton, algal toxins, and, littoral habitat and macroinvertebrates.
 
We work closely with the Lake Stewards of Maine Volunteer Lake Monitoring Program (LSM-VLMP), through which thousands of certified water quality volunteers have submitted data since 1971.  We also train a limited number of volunteers each year to do advanced monitoring on their lake, especially if it is associated with a watershed-based 10-year management plan.  This comprehensive dataset is provided to the public through LSM’s Lakes of Maine website.  It also provides the basis for regional and statewide research studies.  Assessment activities conducted by DEP include water quality trend detection, identification of lakes not meeting their statutory water quality classification of GPA, monitoring prioritizations, and statewide modelling to determine regional patterns.

Data Management

Information is only useful as it’s quality. Keeping track of over a million pieces of water quality data, plus thousands of other related data points, is a huge task. All this information must be as free of errors as we can make it. We follow detailed Standard Operating Procedures and have a program-level Quality Assurance Project Plan on file with EPA.  Our staff cooperates with LSM-VLMP to do periodic quality assurance re-certification visits with the volunteer monitors and perform error-checks on their data. As a result, the data we get from our volunteers is as reliable as data received from professionals. Even our staff has consistency checks each year, and we include careful calibration of our lab and field equipment. We obtain duplicate samples at a rate of 10% and scrutinize the laboratory quality assurance information annually to ensure we get high quality data.

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