When the Northern Colorado Irrigation Company opened the High Line Canal in 1883, the company promised the canal could irrigate 50,000 acres of cropland and supply water for municipal and industrial needs.
But the canal had a junior water right, causing it to go empty during drought years and angering customers to the point of making violent threats. During the 1901 drought, a sign posted at the High Line head gate said, “Any person attempting to close this gate will be filled full of lead.”
It became clear that the canal needed something to supplement its water supply. And so, 100 years ago, Antero Reservoir was born.
Antero, located on the South Fork of the South Platte River in Park County, was built to provide High Line Canal users with a reliable, continuous water supply. Its name comes from the Spanish word “first” because it has the uppermost dam on the South Platte, making it first on the river.
An extinct volcano, the Buffalo Peaks, looms over the 9,000-foot-high reservoir, creating a pristine backdrop for an area that receives very little pristine weather. Temperatures can drop to 40 below zero in the winter, and its high altitude, wind and bugs make an 80-degree summer day at Antero feel like an uncomfortable buggy 100-degree day in Denver.
Denver Water acquired Antero and the High Line Canal in 1924 and later opened the reservoir site to boating, camping and fishing.
The reservoir, which holds a maximum 20,000 acre-feet of water, is shallow compared to other reservoirs. In fact, during the 2002 drought, Antero lost so much water that Denver Water had to drain it and move its water to other storage facilities to prevent evaporation loss. It took another five years for the reservoir to reopen. 
Still, the shallow lake is a prime habitat for rainbow, brown, brook, splake and cutthroat trout. When Denver Water reopened the reservoir after the 2002 drought, a Lakewood man caught the heaviest cutbow trout on state record, a 28.5-inch-long fish that weighed 18 pounds, 8 ounces.
Antero may be a century old, but it remains an important part of Denver Water’s system, as well as a gem to recreationists across the state.