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Climate and Drought


Irrigation and the Union Colony

Click the Fluent Water Facts below to learn more about Colorado's history.

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Turning Colorado Green

Driving across Colorado today, we encounter lush green lawns, thriving cities, and acres of fertile fields. This is not Colorado’s natural landscape – much of it has been made possible through human ingenuity. Most green fields and lawns would not be possible without irrigation. The Union Colony, which established the town of Greeley, also laid the groundwork for Colorado’s modern irrigation and water law systems.

Water Brings Life to the Plains

In 1870, settlers arrived on the plains of northeastern Colorado with plans to found an agricultural town. The members of this group, known as the Union Colony, built shelter first, then turned to their greatest challenge. The success of the colony would depend on their ability to dig ditches that could carry water to their fields.

Irrigated agriculture in northeastern Colorado was very uncommon at the time. Most irrigated fields lay close to a river, but the Union Colony was miles away.

Building the canals was not easy. The first canal was intended to irrigate 5,000 acres, but it was only able to water 200 acres in June 1870. Construction of the next canal nearly caused the colony to go under. It was intended to irrigate 2,000 acres of planted seeds, but its supplies were insufficient for the hot summer of 1871 and most of the crops died. Nevertheless, the canal was eventually completed – 36 miles long and 32 feet wide, an engineering marvel. Within three years, the land was so productive that people stopped worrying about growing enough food to feed themselves, and instead worried how they would find markets for all their crops.

Imitating the Union Colony’s Success

Other towns learned from the Union Colony’s successes and engineered their own irrigation ditches. Greeley pioneers also helped develop irrigation systems for Fort Collins, Colorado Springs, Longmont, and Sterling.

Irrigated agriculture in Colorado is possible through extensive networks of canals and ditches, like those engineered by the Union Colony, as well as other water systems. Today, approximately 86% of Colorado’s water is used for agriculture. Learn more about agriculture in Headwaters magazine.

First in Time, First in Right?

In the dry summer of 1874, the Cache la Poudre River did not have enough water to supply both Fort Collins and Greeley. Fort Collins’ ditches were further upstream, but Greeley’s ditches had been built first. Greeley appealed for the water under the doctrine of prior appropriation – those who claimed the water first should have first priority in times of drought. Both sides recognized the need for some sort of regulation, and agreed to split the Cache la Poudre.

In 1878, construction of new canals prompted a statewide irrigation convention to codify Colorado’s water laws.   About 50 men representing 29 ditch companies and agricultural districts in the South Platte Valley met to discuss how to determine priorities, record water rights, and measure streams. Their work served as a template for legislation enacted by the Colorado General Assembly in 1879. These laws set nationwide precedent. They established Colorado’s prior appropriation doctrine for water law, known as “first in time, first in right.” They also established a court system to adjudicate water rights, and created water commissioners to divide streams according to court-decreed priorities. Colorado now had a legal framework to divide its water in times of need.

Early Water Law

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The First Water Law of the Land

The San Luis People’s Ditch has the oldest continuously operating water right in Colorado, dating from 1852. But its right doesn’t come from Colorado’s prior appropriation doctrine. Today Colorado’s water law is commonly summed up as “first in time, first in right” – the first person to claim the water has the first right to use it in times of shortage. This was not always the law of the land. Nor was the system of riparian rights, common to the Eastern United States, where owners of land adjacent to streams have the right to use the water. Settlers who came to Colorado in the mid-1800s based their water rights on the Mexican system, including the practice of community water distribution through acequias.

Sharing Community Water

An acequia (pronounced “ah-sek-e-ah”) is a water-sharing network based on equitable allocation, regardless of priority. Users build a network of canals and ditches to water their land. Water is granted to users based on the amount of water available, and is divided based on needs and fairness. Farmers can earn water rights through land ownership or farming operations. Each member of the acequia receives one vote in deciding its management. All users are required to contribute to the maintenance of the ditch. The stable settlement of the dry lands of the San Luis Valley required these shared duties of maintenance and equitable use.

Colorado Water Law and Acequias

Acequias were upheld in early Colorado water laws of 1866 and 1872. These early laws recognized a preference for water in agricultural use, rather than industrial and milling use. Consequently, acequias prioritized agricultural use over non-agricultural use in farming season, irrespective of water right decree dates.

In 1889, a set of water decrees established priorities among acequia ditches in the Culebra watershed. Although acequia water-sharing practices continued, rights were increasingly understood and exercised with reference to their priority dates.

Today, many acequias in the San Luis Valley continue to follow traditional practices and customs. Water is still viewed as an asset, tied to the landscape and the community economy it creates. Many acequias function as informal civic associations, rather than formally associated ditch companies. This commitment to older traditions preserves the social fabric of the community and contributes to sustainable agricultural practices.

Ancestral Puebloan Water

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Harvesting Water at Mesa Verde

Mesa Verde may be Colorado’s most famous prehistoric site, and its inhabitants, the Ancestral Puebloans, understood the need to store and manage water. People first settled in Mesa Verde around 550 A.D, eager to grow maize in the area’s rich soil. Maize was an insurance policy against famine, but it required water throughout the summer.

Mesa Verde receives about 18 inches of rainfall annually. Its canyons supply flowing water only during storms or spring runoff. People could supplement this with water from small springs or from shallow, hand-dug wells. But the ingenious Ancestral Puebloans engineered larger-scale solutions to their water problems.

Engineering Marvels

Around 750 A.D., the Ancestral Puebloans built a reservoir in Morefield Canyon by digging a shallow pond in the canyon bottom. When rain fell, it flowed down the canyon floor and filled the pond. Just like reservoirs today, this reservoir needed constant maintenance. Runoff carried silt and sand into the pond, limiting its water storage capacity. The Puebloans regularly dredged the reservoir, using sticks, antlers, stones, and baskets. Dredging required both energy and organization.

The Ancestral Puebloans also built two reservoirs on the mesa top. These did not have the advantage of a natural channel to collect the water, as canyon bottoms do. Modern engineers probably wouldn't attempt such a project. But the Puebloans must have recognized that human foot traffic could compact the silt and clay soils that, when puddled with rainfall, would float up to form an impervious surface, allowing nearly 100% runoff. A half-acre of compacted area could create enough runoff for a successful water harvest.

Drought Brings Dramatic Change

By 1100 A.D., the Ancestral Puebloans had stopped using Morefield Canyon reservoir and one of the mesa top reservoirs. The years from 1135 to 1180 were especially dry, and women needed to trek 500 feet down into a canyon for water from a spring. The Puebloans moved away from the mesa tops and into the famous cliff dwellings, relying on groundwater from springs, seeps, and small hand-dug wells.

Around 1275 A.D., another drought hit, and by 1300 A.D. Mesa Verde was deserted. Its people probably moved into the northern Rio Grande basin, near present-day Santa Fe and Taos.

The Ancestral Puebloans proved that survival was possible in Colorado’s dry southwest. Water was the key to success. But collecting enough water required considerable engineering, careful maintenance, and community effort.

Further Reading

Wright Water Engineers has conducted research on Ancestral Puebloan water sites throughout the Four Corners region.   Read reports of their findings at   http://wrightpaleo.com/wordpress/publications/.

To learn more about Mesa Verde National Park, visit www.nps.gov/meve.

Citizen's Guide to Colorado's Water Heritage

Citizen's Guide to Colorado's Water Heritage

This book draws together the expertise of six prominent historians and scholars from throughout Colorado and the West to explore how water shaped Colorado culture, history and identity. Discover Native American, Hispano and Anglo contributions to our water heritage. Important background reading for those interested in water resource issues, as well as a valuable teaching aid for the classroom.

Read more: Citizen's Guide to Colorado's Water Heritage

Citizen's Guide to Colorado's Environmental Era

Citizen's Guide to Colorado's Environmental Era

This guide extends the history timeline to recent years-what we have labeled "the environmental era." Essays from six prominent historians, authors and environmentalists discuss how the environmental movement has shaped Colorado's culture, communities and landscapes.

Read more: Citizen's Guide to Colorado's Environmental Era


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WEco Climate Resources

Guide to Colorado Climate Change presents a range of contemporary climate change information written by experts. Take a look.

Water 101 Sheets are one-page references available for download and distribution. Explore the basics of drought, and wildfire or read various water conservation tips through a series of fact sheets. Interested in additional resources? Find them herefact_sheetsClimate Workshop
Participants tour the National Ice Core Lab, hear how researchers study climate and what that means locally. Learn more.

Connecting the Drops Radio

Listen to a radio feature on climate change's effects on Colorado farmers, spring runoff, and irrigation.

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