Moffat Water Tunnel West Portal, Colorado

The Moffat Water Tunnel is a ten foot diameter water tunnel running parallel to the larger train tunnel. It was made at the same time as the train tunnel, starting in 1924, as the preliminary “Pioneer Bore”  75 feet south of the main train tunnel. Both run for more than six miles under and over the Continental Divide. The Moffat Water Tunnel has been used as a water supply tunnel for the city of Denver since 1936. The water comes through a large system of pipelines and reservoirs that collect water on the west side of the Divide, and deliver it to the populous east side, via the Moffat Tunnel. Denver Water, as the city’s main water supply company is called, operates four watersheds, three of which are on the western slope of the Divide. The Moffat Collection System has one lobe on the east side of the Divide, and another on the west side, with the Moffat Tunnel between them. By the time some of this water enters the Moffat Water Tunnel, it has crossed the Continental Divide three times, back and forth. At the east portal of the Moffat Tunnel, the water emerges as a canal that joins Boulder Creek, which flows alongside the tracks for around 15 miles, before spilling into the Gross Reservoir.