Most of the information used to produce this analysis is publicly available for free on OpenET and on the state of Colorado’s Division of Water Resources website. These numbers are estimates, based on our best understanding of how to figure the amount of diverted water used by a crop, supplemented by interviews with several experts. Figures for the acreage of irrigated parcels, water rights information, what is being grown on the parcels, if they use flood or sprinkler irrigation and the amount of water diverted by each ditch are from the Colorado Division of Water Resources Decision Support Systems publicly available database. 

It is sometimes hard to know who all the water users are on a ditch. This information is often not public. In the case of the Crystal, it is common local knowledge who most of the biggest water users on a ditch are.  

OpenET is a relatively new, state-of-the-art online platform for mapping evapotranspiration (ET) at the scale of individual fields using satellites. Evapotranspiration is a measure of the amount of water used by crops, also called consumptive use. Historically, much of the public’s and water managers’ understanding of water use has been based on the amount diverted from a stream, not on how much water is actually being used by crops and therefore leaving the local system. By measuring the evaporation from the land into the atmosphere, OpenET fills an important data gap in water management across the western U.S. OpenET is now being used by water management agencies, including by contractors for the Upper Colorado River Commission’s System Conservation Program. Aspen Journalism used the EEMetric model from OpenET since experts told us this model works best in the Upper Colorado River basin and is the model used by the UCRC.

OpenET works best on parcels that are at least 30 meters x 30 meters or .22 acres, like most of the agricultural parcels examined here. It is less accurate for towns and cities, which include smaller parcels, like the residential lawns and gardens that are watered from the Carbondale, Weaver & Leonhardy, Rockford and Bowles & Holland ditches. Therefore, for these ditches mainly used for residential outdoor watering, it is difficult to determine precisely how much of the water diverted is actually used. However, since much of the land under these ditches is hardscape (houses, roads, sidewalks, buildings) and not irrigated land, it is safe to assume they use less than the ditches that primarily serve agricultural land.

The consumptive use numbers from OpenET are a measure of all the moisture consumed by a crop, including from precipitation as well as irrigation. Since the amount of precipitation consumed by the crops could not be determined, as plants do not use 100% of the water that falls from the sky, Aspen Journalism did not include precipitation in these calculations. OpenET scientists told us they are still figuring out how to accurately account for precipitation. Therefore, the amount of water used by the crops from the ditches is probably actually lower than what is reflected in our numbers. 

Aspen Journalism added 5% to the consumptive use numbers to account for the water consumed through evaporation as the water runs through the ditch. 

According to Division 5 Engineer James Heath, published diversion records contain data collected by DWR staff and/or supplied by water users. Water commissioners verify that the diversion complies with the decreed rate and uses, and that the diversion is being placed to beneficial use without waste.

Water commissioners use a phone app to record their observed records at measuring devices just downstream from the headgate, through which they can also upload those records to the state database. Irrigators use their own methods to collect their data and typically will email their records to water commissioners at the end of the irrigation season. 

Heath said the diversion records are the best information available as to the historical operations of ditches.

Some irrigators declined to speak with Aspen Journalism, would not speak on the record or did not respond to attempts to contact them. Thank you to those who were generous with their time and access, providing deeper insights into their operations and opportunities for photos.