is no pipe dream
Several years ago, I forwarded research findings from my former home in the state of Connecticut to the Idaho Department of Fish & Game regarding a situation where a new source of cold water saved a branch of the Farmington River from lethal summer temperatures. A newly-built dam provided the cold water from its 100-foot depths.
Great, year-round fishing resulted.
Connecticut closely monitored the downstream flow and saw little loss of temperature for 20 miles! At that point, the water hit a large body of heated water created by an old mill dam and warmed.
My friends at Connecticut fish and game (I raised trout for them in another life) thought that the cool waters might have made it another 10 miles downstream.
A recently completed siphon in Washington state has worked and has provided more hard research data and cost estimates.
A year-round trout fishery is feasible and would pay huge dividends for anglers and local businesses alike.