Water Woes XL-Back To The Future*
- Mark L. Johnson
- Jun 28
- 2 min read
The Arizona Department of Water Resources (ADWR) has recently floated (pardon the pun) the Supply Driven Concept as a potential solution for the Colorado River Water Supply quagmire. This was discussed at the recent Arizona Reconsultation Committee (ARC) meeting on June 17, 2025 and the following information related to the Supply Driven Concept was gleaned from the meeting presentation materials.
Supply Driven Concept
Lees Ferry is located along the Colorado River approximately 15 miles downstream of Glen Canyon Dam (Lake Powell). See map (right). The Colorado River Compact (1922) established Lees Ferry as the dividing line between the Upper and Lower Colorado River Basins with each getting an allocation of 7.5 million acre-feet per year (MAF). In 1944, Mexico was allocated another 1.5 MAF, bringing the total Colorado River allocation to 16.5 MAF.
There is a United States Geological Survey (USGS) river flow gauge located at Lees Ferry that has been in continual service since 1921. The United States Bureau of Reclamation (USBR) adjusts the Colorado River flow readings at Lees Ferry to account for water depletions (usage) in the upper basin, diversions into and out of the upper basin, and evaporative losses from upper basin reservoirs to obtain the "natural flow" at Lees Ferry**.
The following graph shows the natural flow at Lees Ferry from 1906 to 2024. The 25-year (12.4 MAF), 37-year (13.0 MAF) and 119-year (14.6 MAF) averages are highlighted. All of these averages are less than the aforementioned total Colorado River allocation of 16.5 MAF! This data well demonstrates that the Colorado River has never yielded the 16.5 MAF allocation and the amount of natural flow that is actually available is getting lower over time.
Arizona has correctly concluded that the Colorado River is over-allocated and is now trying to convince the rest of the Upper & Lower Basin states to allocate Colorado River water based on a fixed percentage of the preceding three-year average of the natural flow at Lees Ferry. This in lieu of using reservoir levels and associated shortage criteria. See graphic below. Apparently there is now interest from all the parties in the concept.
We will see what happens in the months ahead but the Cut 20 Plan (see below) is a more straightforward solution.
Cut 20 Plan
Tortolita Alliance (TA) sent USBR a letter (9/1/22) [Colorado River System-Cut 20] recommending that all Colorado River water supply contracts/allocations be cut by 20% (3.5/16.5) across the board (Cut 20 Plan) because the data is clear that the Colorado River was over-allocated by 3.5 MAF at the outset. This is supported by the Supply Driven Concept data presented above. The Supply Driven Concept approaches the Cut 20 Plan but it still involves variables and details that will require yet more negotiation.
Just like Marty McFly, it's time to Go Back To The Future* and take the drastic yet simple action and Cut 20, i.e. reallocate the Colorado River water supply at 13.0 MAF by cutting all Colorado River water supply contracts/allocations by 20% across the board. It is time to stop allocating water that does not exist.
*Back To The Future (1985), Universal Pictures, Robert Zemeckis (Director)-used for educational purposes only.