Monitoring and Assessment of Lakes
Special Studies and Research
DEP is not a “research” agency, but we do have questions which only focused studies can answer. Our research projects are focused on how our lakes and their watersheds function and we often cooperate with the University of Maine, Colby College and others to pursue these projects. 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.
We also get requests from people on topics as diverse as water level management to whether algae blooms are a health concern. Recently, the topic of aquatic plant growth, and nuisance infestations of invasive plants has become a major part of these requests under our Invasive Species Program.
Some areas of current work:
- Biomanipulation Studies- Can we combat nuisance algae blooms by reducing the number of fish that eat macroscopic zooplankton? Very high densities of fish such as white perch reduce the numbers of large zooplankton such as Daphnia that graze on algae. If we can favor higher zooplankton populations by removing some of these fish, we may be able to get some control of algae blooms while we also work to reduce the phosphorus sources that cause the problem. This is part of a multi-year project on East Pond with the University of Maine, partly funded by the US EPA.
- Diatoms and Water Quality- How can we use diatoms (algae) information from the deep sediment of lakes to tell us what the water quality of a lake is? Diatoms have an easily preserved outer shell and many species are known to be good indicators of the nutrient and acidity status of lakes. The answer could allow us to employ a single sampling of a lake to improve interpretation of summertime sampling, infer the status of a lake from one sample if that’s all we have to go on, and even look back in time through historic sediments to see what a lake was like before humans modified it. We have collected hundreds of these samples and in cooperation with other New England states and EPA, we are developing a model to determine lake phosphorus status.
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Ecological Reserve Aquatic Baseline Project- What is the status of aquatic resources in Maine’s Ecological Reserves lakes and ponds? The Ecological Reserves system was established in 2000 on 16 blocks of public lands administered by the Dept. of Conservation to provide opportunities for baseline monitoring and long-term research on representative ecosystems in Maine. With a few exceptions,
relatively little has been done statewide to document aquatic diversity compared to terrestrial systems and these gem public lands offer an opportunity to work in places that will be protected for the future. The DEP Lake assessment Program goals in the Reserves are to:
- Establish baseline information on the reserves that contain major freshwater systems.
- Develop/adapt efficient, robust field techniques
- Document characteristics of undisturbed habitat
- Take representative samples/measurements
- Provide basis for research, more in-depth community work, highlight knowledge gaps
In 2005-08, DEP has done baseline inventories on 31 Reserve lakes and acquired multiple year’s water quality data on dozens more. Future work may also include ponds with intact watersheds that are manages similarly to reserves, such as Baxter State Park.
Other areas we have begun working on include methods to evaluate the effects of water level fluctuations on lake habitat, monitoring algae-derived toxins in oming lakes, indications of the effects of alewife stocking on zooplankton populations in lakes, and evaluating the effects of ultrasound algae control units on non-target organisms.
Water Quality Diagnostic Studies
- 303 (d) List - There are several lakes that do not meet water quality standards, mostly due to excessive amounts of total phosphorus. The DEP are charged with doing studies on ll lakes listed as being “water quality limited” or “impaired” (the 303(d) list reported to EPA every 2 years).
- TMDL Studies - 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 also cooperate with other groups such as the University of Maine, Colby College who do special studies on lakes of interest.
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