Water-Primrose reproduces rapidly, forming dense mats on the surface of the water. These mats can interfere with boat traffic and other recreational activities, as well as, reduce oxygen and light levels in the water column altering food and habitat for wildlife. They can also slow or completely halt water flow and cause sediment accumulations.

Water-Primrose is an aquatic invasive plant on the state of Michigan’s watch list. It is important to prevent, detect, and quickly control watch list species because if left unchecked they can spread rapidly with many negative impacts to the environment and economy.

Water Primrose was discovered in Macomb county in 2023. That same year the lake St. Clair CISMA surveyed 340 acres of Lake St. Clair Shoreline, aiding in early detection and rapid response efforts for this watch list species. In 2024 the CISMA treated 1.3 acres of water primrose along the shoreline of lake St. Clair. In 2024 our survey efforts for water primrose also grew considerably, totaling 2661 acres surveyed.