Opening of Gunnison Tunnel The Gunnison Tunnel was opened in September 1909, bringing valuable water from the Gunnison River, through the Uncompahgre Valley, and to users in Mesa County and adjoining Western Slope areas. The tunnel's dedication was attended by President William Howard Taft and other luminaries. At the time of its dedication, the tunnel was the longest irrigation tunnel in the world at 5.8 miles in length. The tunnel is now a National Historic Civil Engineering Landmark. USA https://www.nps.gov/nr/testing/ReclamationDamsAndWaterProjects/Gunnison_Tunnel.html National Parks Service webpage yes yes