Seasonal Changes

What is the FM River water quality rating? The FM River water quality rating is based on the results of water quality monitoring in the FM metro area and regulatory limits for the different parameters. The FM River rating scale is informal and is intended to be used as an aid in understanding local water quality issues. Click here to learn about the rating scales for the individual parameters.

What are the seasonal ratings for water quality and why is that rating given? The overall rating for Red River water varies from Fair to Good over the course of the year. Why? Because parameters like water temperature, dissolved oxygen, suspended sediment, turbidity, transparency, and the potential for the transformation of ammonia to ammonia gas (toxic to fish) vary with the seasons. These variations make the difference between a Good or Fair rating. Only under extreme circumstances would parameter levels be an impediment to recreation or be harmful to river life. Here is a summary of the seasonal changes.

• Winter - The river water quality is Good overall in the winter. Suspended sediment associated with runoff is low (so the water looks cleaner and the transparency is higher). The low temperatures result in a low potential to generate toxic ammonia gas and a higher capacity to hold dissolved oxygen.

• Spring - During the spring, the water is in transition from the Good rating of the winter resulting from near-freezing water temperatures and low runoff to the Fair rating of the summer resulting from elevated temperatures and higher suspended-sediment content.

• Summer - The water quality of the river is Fair overall in the summer. The rating results from a higher potential for the production of ammonia gas (toxic to aquatic life) and the warm water's lower capacity to hold oxygen. Also runoff from multiple storm events and bank erosion can carry sediment to the river that makes the water muddy and reduces its transparency.

• Fall - During the fall, the water is in transition between the Fair rating of the summer associated with high water temperature and runoff to the Good condition of the winter associated with lower water temperatures and low runoff. During the fall, the capacity of the water to hold oxygen increases and the potential to generate ammonia gas decreases. The suspended load in the river decreases, and the water becomes cleaner and clearer.