A nearby lake should be avoided by swimmers.
Alberta Health Services (AHS) says blue-green algae blooms are affecting the water quality at Heritage Lake.
Not all the lake is contaminated with the cyanobacteria, but people are being advised to avoid swimming or wading in areas where it's visible.
AHS is also warning the public of feeding whole fish or fish trimmings from the lake to pets.
Blue-green algae can cause skin irritation, sore throat, red eyes, swollen lips, fever, nausea, vomiting and diarrhea.
Heritage Lake is less than a kilometre west of Morinville.