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Environment

• Water Quality, Eurasian Milfoil, Shorelines, Fishing, Flora & Fauna, Wetlands

Overview

Lac Mahon is a small, shallow, warm lake with wetlands and wildlife diversity. There is much natural shoreline, which is a sensitive habitat, and a particularly sensitive period is from May 1 to August 30, the nesting period for loons and other water birds.

• Depth chart, Online depth chart

Since sunlight can reach the bottom for much of the lake, plants can and do grow there. The natural state of a healthy shallow lake is to have abundant aquatic plants, providing important wildlife habitat and resting areas for migrating waterfowl. The plants lock up nutrients so there is no dense algae growth, produce oxygen, keep sediments stable (including nutrient deposition), and are hiding places used by zooplankton, which eat algae.

Shallow lakes are vulnerable to human impact, and can become dominated by algae. To avoid excess nutrients and help keep a shallow lake healthy, 

• • Preserve aquatic plants that tie up nutrients.

  • Don't disturb lake-bottom sediments with prop wash from motor boats (see Shorelines, Boating).

  • Maintain (or restore) natural vegetation on lots and shorelines to soak up and filter runoff, and prevent soil erosion.

  • Don’t use soaps or detergents containing phosphates.

• Don’t use fertilizers or pesticides.

• Have a proper septic system (including grey-water disposal) that is in good order and pumped out regularly.

Natural eutrophication (lake aging) takes place when lakes receive nutrients and sediment from the surrounding watershed and become more fertile and shallow. Cultural eutrophication is caused when humans speed up the process by adding excess nutrients and sediment quickly.

At the 2015 AGM, Association members agreed that options be costed out for an environmental assessment of the lake and its surroundings, e.g. a wildlife and habitat survey.

The following one-page documents provide a good overview of environmental issues:

• For our lakes health and our own

• Every drop counts

• On the menu - a diet low in nitrogen and phosphorous

• Are you a healthy (boat) navigator?

• The lake blues (blue-green algae)

• Does your lake have good kidneys?

• Skeptical about your septic facilities?

• The shoreline - the lake's natural shield

  • A green world in a watery universe (aquatic plants)

  • Gardening - health insurance for our lakes (shoreline vegetation)

Links

• Lakes and watercourses - Ours to save

• Lake eutrophication

• Shallow lakes and plants vs. algae

• Shallow lakes - an important yet vulnerable habitat