Delta Marsh covers 190 square kilometres on the southern shores of Lake Manitoba.
The $3.5-million project aims to keep destructive fish from entering the marsh by putting up screens at strategic points.
Common carp do not overwinter in the marsh, but return in the spring and summer and disrupt the ecosystem by uprooting vegetation and stirring up silt.
This stops sunlight from reaching other aquatic life and eventually makes the marsh stagnant and unable to filter out pollutants.
Manitoba Conservation Minister Gord Mackintosh says restoring Delta Marsh will ensure the survival of healthy fish, water fowl and clean beaches.
Ducks Unlimited is contributing $3 million of the project's total cost and will supervise the undertaking.