The Colorado River has again dominated headlines with a six-state letter sent to the Bureau of Reclamation on Jan. 30. That letter was in response to Reclamation’s public scoping process for a Supplemental Environmental Impact Statement (SEIS) that intends to supplement the 2007 Interim Guidelines (part of the Law of the River). We thought it would be helpful to delve into the basics of this federal process – so here’s your explainer – using several other explainers of our own!
What is a SEIS?
Reclamation intends to modify the operating guidelines for Glen Canyon and Hoover Dams, which hold back Lake Powell and Lake Mead, respectively. Any such actions modifying the current operating guidelines must comply with the National Environmental Policy Act (NEPA). This will require a Supplemental Environmental Impact Statement (SEIS) – supplemental to the Environmental Impact Statement (EIS) in place under the 2007 Interim Guidelines.
This process is distinct and different from the NEPA compliance process that Reclamation will begin for an EIS related to new operating guidelines that will go into place after 2026. That will be a separate process.
Why is this SEIS necessary?
The Colorado River Basin relies on runoff from the snowpack in the Rocky Mountains and Upper Colorado River Basin. The Colorado River Basin has been experiencing more than two decades of drought, and the past couple years have seen some of the lowest runoff. These conditions have been exacerbated by aridification due to climate change.
Revisions to the 2007 Guidelines are necessary to protect all who depend on the Colorado River – more than 40 million people, 5.5 million acres of irrigated farmland, 30 Basin tribes, environmental resources across seven states and parts of Mexico.
What did the six-states participating in this letter (Arizona, Colorado, Nevada, New Mexico, Utah and Wyoming) suggest as part of this SEIS process?
The letter outlined a Consensus-Based Modeling Alternative. It’s first helpful to understand the term “modeling.” You can learn more about current modeling efforts here.
The proposed modeling alternative includes:
- Adjustments to shortage reductions under the 2007 Interim Guidelines and contributions required under the Drought Contingency Plan— this includes moving into Tier 3 shortage at Lake Mead elevation 1050’ (as of the Feb. 2 CAWCD Board meeting, this level was reported below that – at 1046’)
- Accounting for more than 1.5 million acre-feet of evaporative losses within the Lower Colorado River Basin
- Additional reductions at Lake Mead elevation 1030’ and 1020’
- Actions outlined within the Upper Basin State’s Drought Response Operations Agreement
Does this mean operating conditions will change right away?
This modeling alternative is not a formal agreement and does not change current operating conditions (currently, the Lower Colorado River Basin is in a Tier 2a shortage). Rather it provides an alternative framework for Reclamation to analyze in its SEIS process. Reclamation is expected to release its draft SEIS in March 2023 and a final SEIS in late spring. A record of decision could come in summer 2023 that would allow for implementation in 2024.
How can I learn more?
As more information come available we will continue to post in the River Updates section of our Know Your Water News site.