How A Lake Ages

Damariscotta Lake began its life when the glaciers receded, about 10,000 years ago. It will end its life when it is filled with sediment from the watershed and becomes a marsh. Long before it becomes a marsh, it loses its clarity and oxygen and becomes ridden with nutrients, algae and aquatic plants. Lake conservation requires slowing the aging process by reducing the flow of sediment and nutrients into the lake from the watershed.

There have been times in the past when the rate of aging has been accelerated by logging and agriculture. However, the rate of aging may reach its peak in the future as development brings soil disturbance and vegetation loss. Damariscotta Lake is one of a group of Maine lakes most at risk for accelerated aging from development.

Some important signs of old age in a lake:

1. Increasing nutrients - The critical nutrients are nitrogen and phosphorous. Air pollution has saturated Lake Damariscotta with nitrogen, thus attention is focused now on preventing phosphorus from entering the lake from the watershed.
2. Loss of clarity - This is due to suspended sediments, microscopic plants, and other forms of algae clouding the water. Sediments come from the watershed. Algae appears when nutrients are plentiful.
3. Decreasing oxygen - This happens with the growth of plants in the water, including algae.
4. Changes in fish species - As the oxygen in the water decreases, those fish species (e.g. salmon, trout) die off, leaving only those species that can survive with low levels of oxygen.

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