A May 22, 1990 Maine DEP internal memorandum titled "Sebago Lake Water Levels" written by Maine DEP technical staff member Jeffrey Dennis states:

"According to the water level data which you provided the recent water level management of Sebago Lake has resulted in water levels consistently 1 to 2 or more feet higher than the normal water level regime for 7 to 10 months of the year. I was happy to hear that S.D. Warren has agreed to return to their former, traditional water level management program, because continuation of the elevated water levels of recent years could significantly impact water quality."

[Editor's note: This return to historic lake levels never happened. Less than one year after Mr. Dennis wrote this memo in May 1990, Maine DEP Commissioner Dean Marriott withdrew his support for returning Sebago Lake to its natural, historic water levels. This has remained the case for the past 16 years.]

Mr. Dennis' memo continues:

"The two water quality impacts of greatest concern to us in this situation are (1) the increased potential for shoreline erosion and resultant phosphorus loading and habitat relocattion and (2) the increased potential for phosphorus contribution to the lake from marginal shoreline septic systems.

"Lake shorelines are a result of the long term cumulative effect of erosional sedimention processes. The location and character of the shoreline are a function of the water level on the lake as well as the type and distribution soil and geologic formations in the shoreline area. If a lake's water level regime remains consistent with only natural (or the equivalent) fluctuations over a long period of time, the shoreline will reach an equilibrium with that particular water level regime. This means essentially that most of the erosion which is likely to occur has already occurred and that additional significant erosion is only likely to occur if the water level regime is significantly modified, either naturally or by human manipulation. The length of time which it takes to establish this equilibrium is dependent on the nature of the shoreline's soils and parent material. A shoreline in marine clay may take a very long time to reach equilibrium and the naturally stable location of the shoreline may be a long horizontal difference from the original shoreline location. Less erodable materials will reach equilibrium quicker and result in steeper stable shorelines.

"The recent substantial increase in the average water level of Sebago Lake has exposed shoreline soils to erosional forces at a greater frequency and intensity than before, thus disturbing whatever equilibrium had been established under the previous water level regime. In portions of shoreline with the most erodable soils and greatest exposure to wave action this has no doubt resulted in substantial erosion, undercutting and destabilization of banks, failure of manmade erosion control structures (e.g. retaining walls), loss of near shore trees and their associated stabilizing root systems, suspension of finer soil particles in the water column and deposition of both coarse and fine particles in the littoral zone. Unless a very high percentage of the shoreline is either naturally resistant or artificially protected from the increased exposure to erosional forces, the resulting phosphorus loading from the eroded soil particles could be substantial. Although not all of this phosphorus is available for algal production at least some of it can be directly harvested by algae, and more will eventually become available as a result of exposure to bacteria and other metabolic processes ....

"Anything that can be done to minimize phosphorus loading to Sebago Lake, particularly something as simple as controlling water levels, should be. The other cumulative sources of phosphorus to Sebago Lake, probably our most valuable lake resource, are diverse, distributed throughout the watershed and comparatively difficult to address. It is unlikely that any other single act could benefit Sebago Lake's water quality as much as effective water level management. Such management must include an effort to minimize periods of 'abnormally' high water levels, and should be included in S.D. Warren's long term hydropower plan."