Gunnison River Basin (Montrose)
Division 4 includes the Gunnison River basin, San Miguel River basin, lower reaches of the Dolores River basin, and the Little Dolores River basin. Our staff administers water rights for water users, consults on water court cases, measures water flow, inspects dams to determine safe water storage levels, and maintains gaging stations and water records within these basins. Most streams within Division 4 are considered "over-appropriated", meaning that enough water does not exist during part of the year to satisfy all decreed uses. The Aspinall Unit of the Colorado River Storage Project is located in the Gunnison basin. Aspinall Unit dams include Crystal, Morrow Point, and Blue Mesa. Blue Mesa Dam impounds the largest reservoir in the State at a capacity of 940,800 acre-feet. These reservoirs are critical in protecting Colorado’s ability to fully develop its apportionment of water under the Colorado River Compact by providing stored water for use in-state and to help ensure that the upper basin states can meet their flow obligations at Lee Ferry, Arizona; thus reducing the potential for a call from the lower basin states.
Important Links
The Division of Water Resources (DWR) has focused on measurement rules in recognition of the importance of measuring both surface water and groundwater diversions. We are now conducting a formal effort to develop measurement rules in Division 4. Measuring surface water and groundwater diversions is important in Colorado to allow for accurate administration of water rights, establish a valuable record of use for water rights, and provide useful information for operating decisions.
Colorado water law requires that water diversions have a proper diversion structure and measuring device where necessary. Measurement Rules will give guidance, structure, and certainty to the Division Engineer’s implementation of that statutory requirement, which is critical in areas that are experiencing more demand, intrastate administration, and the need to protect Colorado interests related to the Colorado River Compact.
DWR held a series of stakeholder meetings from April 30th, 2025 to May 7th, 2025 discussing the proposed Measurement Rules. A recording from the May 1st, 2025 Meeting held in Gunnison is now available on DWR's Youtube Channel.
Please submit all comments on the draft rules through the Division 4 Measurement Rules Comments Form by May 31st, 2025. If you wish to submit your own redline version of the rules, please email it to both marie.sullivan@state.co.us and jason.ullmann@state.co.us.
Use the Subject Search below to locate documents of interest related to the rulemaking, such as draft and redline rules and stakeholder meeting agendas.
All parties can keep informed about this rulemaking through DWR's notification list tool. From the website top navigation, select Public Information, and Notification Lists. Once on the notification lists page, you will be able to login and manage your notification lists and/or register for the notification list Division 4 Measurement Rulemaking Stakeholders, to receive emails concerning this rulemaking process from our office.