Pagosa Springs
The Pagosa Springs Town Park and Centennial Park lie along the San Juan River. They are connected by the San Juan Riverwalk.
Here is the town website. Phone is 970-264-4151. Thank you to Becky Herman for letting me know about this riverside trail where she likes to go birding when its free of snow.
San Juan Riverwalk 1.9 miles described on AllTrails.