The Portland Water District, in its third annual State of the Lake Report released last week, declares the water quality of Sebago Lake “excellent.”

Seven thousand copies were mailed to area residents and interested parties, and additional reports may be picked up at the Portland Water District Ecology Center in Standish at Routes 237 and 35.

The report said that Sebago Lake represents many things to many people, beyond being a source of drinking water for the Greater Portland area. A popular vacation destination for well over 100 years, the lake has year-round residents along its shores in the towns of Casco, Frye Island, Naples, Raymond, Sebago, Standish and Windham. Fishing, snowmobiling, hiking, swimming, diving, canoeing and kayaking are just some of the activities enjoyed in, on, and around Maine’s deepest lake, the report said.

The report is the result of an effort by the District to keep the lake neighbors up-to-date on issues that affect the water source, and the ecological steps necessary to protect that source.

Some of the threats to the water in Sebago Lake, it says, are invasive plants, pollution, fertilizer and insecticide runoff, fuel spills and other forms of abuse that can spoil the lake. The District’s report used several indicators to examine the current health of the water.

One section of the report reads, “If we allow Sebago Lake to deteriorate, we would lose a vital resource that could never be fully restored to its current beauty and purity. No one in a partnership gets everything their own way. An ideal drinking-water lake has no recreation on it and no development around it. Enforcing some moderate rules protects multiple uses and preserves a precious resource for future generations.”

The “State of the Lake” goes on to report on water quality, fisheries, land development, lake level, invasives and boat launch.

Below are summaries from the report:

Water quality: Excellent. With a trillion gallons of cold, clean water, the lake is a valuable source of drinking water for about 200,000 area residents in 11 Maine towns.

Fisheries: Sebago Lake is home to one of only four Maine populations of landlocked, indigenous Atlantic salmon. The salmon show a steady improvement in growth over the last three years. There are also lake trout, and that population appears to have stabilized over the last few years as well. The presence of northern pike has been proven by catches of the non-native, predatory fish in the lake. This species of fish will adversely affect fishery recovery efforts if it becomes self-sustaining.

Land development: The report says, “The Erosion and Sedimentation Control Law requires sediment control measures to be in place before work begins at a construction site. Beginning July 1, 2005, all chronically eroding sites in watersheds most-at-risk must be stabilized. Examples of chronic erosion problems include camp roads that wash out each spring, culverts with erosion at the inlet or outlet, and ditches showing major rills and gullies.”

Lake level: The demands on the lake from competing interests, like paper manufacturing and electricity production, as well as ecological interests, have necessitated allowable levels of water controlled by various dams. The level of the lake has historically been managed over an average 5-foot fluctuation range.

“The plan in place calls for maintaining the lake level within varying levels between May 1 and November 1. Low levels are needed during high storm periods to offset erosion. ‘Low water’ years are an attempt to model the historical lake level regime and build up shorelines that may have eroded during higher water years,” said the report.

Invasives: Non-native milfoils have been spread to Sebago Lake. These plants can choke shallow water areas and ruin native habitation and lake recreation. The District employs a summer boat launch inspector in Standish to prevent these plants from entering or leaving the water of the lake. The Department of Environmental Protection is also taking aggressive actions wipe out milfoils in all Maine lakes.

Boat launch: Thousands of boats enter Sebago Lake each year from a variety of access points. The District monitors this boat activity and has employed attendants at launch sites to educate the users about protecting and preserving the quality of the lake water.

For information about the report or other water quality issues, contact the Portland Water District at 774-5961, extension 3306, or email to sebagolake@pwd.org