Mention one physical characteristic of stormwater runoff that can be monitored.

Turbidity is an important physical characteristic of stormwater runoff that can be monitored. It refers to the cloudiness or haziness of water caused by the presence of suspended solids, such as sediments, organic matter, and pollutants. Monitoring turbidity is vital because high levels can indicate water quality issues, including the potential for harm to aquatic ecosystems. Elevated turbidity can interfere with the growth of aquatic plants, negatively affect fish and other wildlife, and diminish the ability of water to support aquatic life by reducing light penetration.

While the other options, such as temperature, phosphorus content, and volume of runoff, are also relevant for monitoring water quality and management, turbidity directly assesses the clarity of runoff, providing immediate insights into its potential impacts and the effectiveness of stormwater management practices.