Mission Statement: Lake Assessment Section
To promote the protection of Maine's lakes through research, collection and management of sound scientific data, identification of threats to lake ecosystems and dissemination of information to those concerned with lake water quality.
The “Lakes Assessment" Program at DEP includes monitoring and assessment, special studies and research, water quality diagnostic work, and lake restoration. We share data and consult with other agencies, university programs, and the public. The program also partially funds volunteer monitoring, education and outreach, and technical assistance for local watershed projects.
There are also other important DEP programs which directly affect lakes, such as Shoreland Zoning, Watershed Management, Natural Resources Protection Act (NRPA) permitting and enforcement, and the Invasive Species Program.
Lake monitoring
Much of the lake monitoring in the state is done to assess "trophic state" or the productivity of the water. Our 30 year record includes data on over 1000 of our 5785 lakes, including parameters such as transparency, conductivity, alkalinity, total phosphorus and chlorophyll-a. These, along with extensive data sets from the University of Maine and clarity readings from volunteers, have produced one of the most comprehensive lake data sets in the country. Much of these data are available through the PEARL website.
DEP regular monitoring includes annual Baseline Sampling Program and special projects of one or more years’ duration. Each year between August 10 and September 10, we visit over 100 lakes and take a number of types of data. The timing coincides with the period when lakes usually show their worst water quality: lowest dissolved oxygen, lowest transparency and highest algae and phosphorus levels. Besides these measures, we sample for conductivity, alkalinity and acid neutralizing capacity (ANC), true and apparent color, and a variety of cations and anions. Over the last 5 years, we have collected biological samples for zooplankton, pytoplankton and sedimented diatoms as part of ongoing bioassessment projects.
We also work with the Volunteer Lake Monitoring Program (VLMP), which has over 400 volunteers working on more than 350 lakes each year, and train a limited number of volunteers each year to do advanced monitoring on their lake, especially if it is associated with a regional or multi-year project, or for Town Comprehensive Planning.
These data allow us to give some recent information to our monitors and the public. It also allows regional and statewide studies into lakes questions ass varied as the relationship between watershed conditions and lake vulnerability to phosphorus loading or the link between lake water quality and economics. Sampling during other times of year is done in response to specific data needs such as setting appropriate water quality goals for watershed management or responding to reports of algae problems by local residents.
Assessment activities include water quality trend detection, data management and quality assurance and analyzing our data record to understand how our lakes work.
Trend detection
We now have enough transparency data on about 160 lakes to determine if there are obvious trends of improving or declining water quality for these lakes. In conjunction with more detailed analyses, trend detection can help alert us to lakes which may still have good, but declining, water quality. Lakes change slowly, and thus show a “lag time” in response to changes in their watersheds. A lake with a positive water quality trend could be on the verge of reversing that due to development or other changes that took place a few years or a decade ago. Sorting out the reasons for water quality trend is a lake-specific task. The Lake Assessment Section continues to explore analysis issues such as the minimum amount of data needed for reliable predictive usefulness, how short term trends relate to longer term, natural fluctuations, and the potential for other types of data to be incorporated into our analyses.
Data Management
Information is only useful if it is high quality. Keeping track of over 400,000 pieces of water quality data, plus thousands of other related data points, is a huge task. All this information must be available at a moment’s notice, and as free of errors as we can make it. We have develop a detailed set to Standard Operating Procedures and Quality Assurance Project Plan which guide both data acquisition (monitoring) and handling (data management). Our staff cooperates with the VLMP to do periodic quality assurance and re-training visits with our monitors and error-checks the data we receive from them. 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 duplicate-sample 10% of our field data and scrutinize the laboratory quality assurance information annually to ensure we get high quality data.
Providing information
Practically every day, our staff receive requests from prospective lake property buyers, town officials, students, and others about the water quality of a particular lake. We also have to field questions about people’s observations and concerns: everything from algae blooms to pollen on the water and even freshwater jellyfish. Some of these require field reconnaissance or examination sample in our lab. We also have to provide extensive regional analyses to EPA on the conditions of our lakes (“305(b) “ reports) every two years.
Special Studies and Research
DEP is not a “research” agency, but we do have questions which only “applied” research can answer. Examples of such questions include:
We use our extensive data, coupled with new information specifically acquired for the purpose, to determine things like the sensitivity of lakes to dissolved oxygen loss, the effect of natural color on algae growth, and the tendency of lakes to thermally stratify during the summer. Some phenomena, such as regional patterns of lake types, can only be studied using years of data from many lakes over broad regions. These studies can help us estimate how sensitive a particular lake may be to oxygen loss or its potential to form nuisance algae blooms under changing conditions. For example, “Water Quality Categories”, which help determine the capacity of a lake to accept new phosphorus from it watershed, are derived using our historical data. Designating “Priority Watersheds” also rely in part on these data.
We also get requests from people on topics as diverse as water level management to why shoreline vegetation should be kept intact. Most recently, the topic of aquatic plant growth and the potential for infestations of invasive plants has become a major part of these requests under our Invasive Species Program.
Our research projects are focused on how our lakes and their watersheds function. We often cooperate with the University of Maine and others to pursue these projects.
Areas of recent work include:
* Relationship of lake water quality to economics in Maine
* Potential for lakes to develop low oxygen conditions which threaten fisheries
* Relationship between watershed characteristics and lake water quality
* Potential of biological monitoring in evaluating lake conditions
* Effects of shoreline development on littoral (near shore) habitat
* Regional and physical classification of lakes
* Factors influencing vulnerability of lake to Invasive species.
Water Quality Diagnostic Studies
We are charged with doing studies on all lakes listed as being “water quality limited” (the 303(d) list). Statewide, there are approximately 35 lakes that do not meet water quality standards due to excessive amounts of total phosphorus. These are lakes which have significant water quality problems and which are not likely to improve under the current conditions of land use and management. The lake diagnostics, so called “TMDL” studies, detail the type of problem, sources contributing to the condition, goals to restore water quality. They also contain recommendations for actions which will achieve these goals.
We have developed a cooperative study approach, employing local agencies, volunteers, and staff of the Maine Association of Conservation Districts, as well as the county districts themselves.
Lake Restoration
Although DEP has done over 15 water quality restoration projects of varying complexity since the mid 1970’s, the realization that these projects are both extraordinarily expensive and sometimes of limited benefit has led us to de-emphasize restoration in favor of more cost-effective assessment and protection activities. Restoration projects have typically involved lakes that have nuisance levels of algae growth. These projects have dealt with phosphorus (P) as the nutrient which drives the excessive growth. A number of techniques have been used to reduce phosphorus inputs to lakes. These techniques deal with sources as varied as diversion of treated wastewater from the lake to internal loading reductions using aluminum treatments (nutrient inactivation). Increasingly we have concentrated on reducing sources of phosphorus and sediment in runoff by using “Best Management Practices”, especially as part of the TMDL process.
“Restoration “ can be a misleading term, as lakes are rarely returned to the condition they were in before humans radically changed their landscape and water chemistry. Rather, we usually strive to bring the lake back to an “acceptable” level of water quality and to persuade watershed residents to take the long-term measures to maintain that improved condition. Increasingly, we work on lakes that have not been significantly degraded, by promoting assessment and watershed management projects through our program and the Division of Watershed Management.
You can contact the Lake Assessment Section at (207)287-3901. For questions about the content of this page, contact Roy Bouchard.
The Lakes Assessment Program