Irrigation in the southwestern region of Colorado has a long history dating back to stone terrace check dams created by the Anasazi, to more modern methods built by the Navajos and early Mexican American settlers.
Rapid settlement on the western slope of Colorado placed a great strain in limited water supply. This was especially true for the Montezuma Valley where irrigation water supply was insufficient for the amount of growth. Nevertheless, this did not inhibit settlement as Montezuma valley was an ideal fruit growing location with more area available area than the thinner Dolores River valley.
Fortunately, the need for irrigation supply promoted formation of companies to construct diversions from the abundant supply of water in the nearby Dolores River. Examples include The Dolores, Dolores Number Two Land and Canal, Lost Canyon, and Montezuma Ditch companies. Diversion projects included a tunnel (one mile long), "the Great Cut" (4,000 feet long), siphons, and wooden flumes. Work started in 1885 on the mile long tunnel under the Dolores divide for water diversion but stopped due to lack of fiscal support. This delay prompted James W. Hanna (speaker of the Colorado House of Representatives from 1891 to 1893) to organize the Montezuma Water Supply Company to restart the tunnel construction along with a water supply system. In order to accomplish this, Hanna secured investments and created the Cortez Land and Investment Company for irrigation pathways. J. M. Mack served as engineer and chief designer for the irrigation system. Mack was also credited with the Cortez town site layout in 1886.
The diversion tunnel was completed in 1889 and was considered one of the greatest irrigation enterprises in Colorado and the West. Due to Mack's affiliation with the Cortez town site, he (as a conflict of interest), diverted funding from other water projects to build a three-mile flume to supply the town of Cortez with domestic water.
The Montezuma Valley Water Supply Company optimistically planned to supply water to an expected population of 50,000 residents in Cortez and to irrigate 200,000 acres of land south and west of the San Juan and Dolores Divide. Water from the Dolores River was appropriated to supply this area and in 1892 the water court adjudicated 1300 second feet (cfs) of flow. This amount is still large enough to serve the valley today. Prior to this appropriation, water rights in America were determined by English Common Law or Riparian Rights. This meant that landowners bordering water could use it provided they did not diminish or alter flow. These rights were based on areas of humid climates and did not work for arid locations like southwest Colorado. It was the Doctrine of Prior Appropriation (endowing first users with permanent right to water as long as they needed it and continued using it beneficially) of water rights that made the use of Dolores River water by Montezuma Valley possible.
From the beginning, the process of supplying Montezuma valley with irrigation water suffered monetary, design, maintenance, damage, organizational, political, and other setbacks. But, due to prevalence over time, water supply to the area grew with additions of reservoirs, canals, and pipelines. Due to sloping topography to Cortez from source water (most likely a factor in Mack's layout for the town site), domestic water can be furnished by gravity alone. Today, the Water Division of Public Works serves a population of 8,776 residents. The water division treats water for the Ute Mountain Ute Tribe and the Montezuma Water District #1. Water storage consists of three tanks with a total capacity of 6 million gallons. Water is delivered utilizing an extensive distribution system with over 425,000 linear feet of pipelines, isolation valves, metering, and system control. All of this combined with a quality source provides good, clean water supply for sustainability and future growth of the City of Cortez.
The River of Sorrows: The History of the Lower Dolores River Valley. Chapter 3 - Eastern Capital and Frontier Initiative: The History of the Montezuma Valley Irrigation System. By Maureen Gerhold. As found and published on the National Park Service website, park history, online books.
Brief History of the Development of the Montezuma Valley Irrigation Co. and it's Ditch system. A summary written by W.L. Glenn, Superintendent, MVI Co. As found and published on the Colorado State University Library website.