The Trinity turned "purple" on Friday through Fort Worth's Trinity Park in honor of the TCU Horned Frogs football team.
A honorary proclamation by Mayor Mike Moncrief is also renaming the river "Horned Frog River."
"TCU football has made the entire city of Fort Worth extremely proud of its efforts this season," said Mayor Mike Moncrief. "While we know there is one huge game to go on Saturday, the city of Fort Worth, in conjunction with Tarrant Regional Water District and Streams and Valleys, wanted to show our support of the Frogs in a big way."
Workers used a food-coloring type of dye to turn the water purple and it will stay that color until the Frogs' season is over.
The Horned Frogs have already captured a share of the Mountain West Championship and are now in pursuit of a BCS bowl.