Aspen Journalism A fly fisherman on the Blue River in Silverthorne on Nov. 28, 2020, which is designateda "gold medal" status based on the size and abundance of trout. A downstream ranch is proposing adding phosphorus to the river in an effort to improve fish habitat. John Herrick/Aspen Journalism A private ranch is seeking Colorado environmental regulators’ permission to inject the Blue River with phosphorus — a chemical regulated as a pollutant — as part of an experiment that could help improve trout habitat at a popular high-country fishing destination. Kremmling-based Blue Valley Ranch, owned by the billionaire philanthropist Paul Tudor Jones II, proposes beginning the project as soon as next summer on an 8-mile stretch of the river running through its 25,000-acre ranch, which is located on both sides of the river between Green Mountain Reservoir and Colorado River.