Opinion: Climate change and Boulder’s shrinking water supply

I’m not a professional water supply engineer.

But I’ve learned enough over my decades of involvement in our city government to be very concerned about our future ability to keep providing adequate water for existing residents and businesses, much less the significant amounts of additional development being approved.

Boulder’s water comes from three sources:

The city-owned watershed is on the east side of the Continental Divide, from South Arapahoe Peak to Niwot Ridge. It feeds many small reservoirs, and then comes via pipeline from above the Peak-to-Peak Highway to the Betasso treatment plant on Sugarloaf Road.

We also own water coming down Middle Boulder Creek, stored in Barker Reservoir near Nederland, and delivered via the Boulder Canyon gravity pipeline past the Boulder Canyon hydroelectric plant to Betasso.

About a third comes from our shares of the Colorado-Big Thompson Project (managed by the Northern Colorado Water Conservancy District), piped from the Colorado River through the Continental Divide, down to Carter Lake near Loveland, and then to Boulder Reservoir, where it is treated. According to city staff, we use more Colorado River water in dry years than wet.

A few data points I’ve seen regarding climate change: We are in a 1,200-year drought. Over half the contiguous U.S. was in drought at the beginning of May, per government climate officials. This year’s Colorado snowpack is way below average; some reports have it at two-thirds of historic norms. Reservoirs upstream on the Colorado River are being drained to keep enough water in Lake Powell and Lake Mead to run the hydro generators. The final NOAA forecast for the season predicts the amount of water to reach Lake Powell this year at about 60% of average.

Our warmer and drier climate affects not just the amount of water, but the timing of its arrival at Boulder’s reservoirs.

Early runoff means water is not stored in the snowpack as long, so our reservoirs must absorb water earlier and so hold it longer, creating concerns about capacity as well as issues with exchanges we do with other water rights holders.

And of course, with less water overall, our ability to manage it becomes even more difficult.

A potentially bigger concern is our Colorado River water. The legal structure for owning this water is based on the 1922 Colorado River Compact. This agreement, formulated during a period of above-average flows, gives the Lower Basin states (California, Arizona and Nevada) first rights on 7.5 million acre feet per year (maf/yr) on a 10-year running average.

The Upper Basin states (Colorado, Wyoming, Utah and New Mexico) get whatever remains, except for a share owed to Mexico (initially 1.5 maf/yr, but reduced now to something less, per my understanding.) An acre-foot of water covers one acre with water one foot deep.

This may seem like a bad deal for the Upper Basin, and it is. But as Patricia Rettig noted in her excellent May 5 Camera commentary, some say that “renegotiation is politically impossible.” Data on the usage by the Upper Basin states is hard to get, but one paper I read has that total at slightly below 5 maf/yr in 2020.

The problem is that the guaranteed 7.5 maf/yr for the Lower Basin plus Mexico’s share plus current Upper Basin consumption is more water than the Colorado River has.

That means the Upper Basin must cut its usage, plain and simple. Per a 1948 agreement, Colorado gets 51.75% of the Upper Basin’s share.

Things gets worse for Boulder because of “pre-compact rights.” These are water rights that preexisted the Colorado River Compact. Another paper I read indicated that users in the Upper Basin states own at least 2.2 maf/yr of these rights; Colorado users own about half of that.

Plus, there are conditional rights that predate the compact, but were not being used when the compact was created. And then there are claims by Indigenous people for additional rights, reducing available yield even more.

So more than half of what, in theory, is left for the Upper Basin states’ water users could go to these precompact water rights.

So, there won’t be much left for our shares of Northern District water (which serves multiple municipal and agricultural users, and is already down to about 70% of original yield), because the district was created in 1937, well after the compact. Thus, it’s “junior” to all these other entities.

So, when all this hits the proverbial fan, the only question is — what’s left, if any, and who gets cut off?

Popular Posts

Opinion: Opportunity for the new Boulder City Council

Congratulations to the four new Boulder City Council members! You have a great opportunity to make a contribution to the Boulder community, but it will take a lot of work to do it responsibly; the learning curve is pretty steep. Here are some suggestions for you (and other Council members) that may help improve the process. Read the Charter. It is the document that governs how you, city staff, and board and commission members operate, and how you relate to each other. It defines the limits of your and their power, and can only be amended by a citizen vote. You don’t have to remember every word. But just knowing what’s there makes you more self reliant and less at the mercy of others’ opinions. For example, relative to the recent meeting discussion over diversity, the council does  not  have the power to suspend the rules as to when the mayor is selected. Charter Section 14 specifies, “The mayor shall be chosen by the council from its own number, upon the convening of t...
Read more

Opinion: Is this the end of Boulder as we know it?

Much of what has made Boulder such a great place to live has been the work of people half a century ago. These people recognized what I call the “ ratchet effect ,” that bad development decisions cannot be undone, so policies needed to be put in place to prevent, or at least limit, the damage that a growth-at-all-costs majority of the council could do. These policies include charter limits, like the Blue Line that prevents city water for development from being supplied above a certain altitude, the 55-foot height limit that has prevented high-rise development from cutting off our views, and the open space referendum process that allows a 60-day window for citizens to challenge disposals of open space. Other constraints include the Boulder Valley Comprehensive Plan’s requirement for Planning Board agreement for land-use changes in the area inside the city limits (Area I) and additional agreement by the county commissioners and county Planning Commission for urban development further...
Read more

Policy Documents: Impact Fees and Adequate Public Facilities

I am writing this to correct some of the apparent inaccuracies put forward at the 10/14 CC/PB study session about charging growth for its costs. I do not claim to be an expert in the field, but I have studied it long enough and consulted with enough supposed experts and legal types to understand most of the basics. In addition, I have found that the experts don’t necessarily know everything and won’t necessarily put forward the most appropriate solutions. The fundamental rule, both legal and equitable, is that growth should pay to address its impacts so as to maintain existing levels of service (LOS) for existing residents and businesses. But growth cannot be required to improve levels of service. LOS is measured in all sorts of ways depending on the facility and/or service being measured. For transportation, it could be total VMT, travel time, intersection waits, access to transit, etc. For schools, it might be square footage per pupil, etc. For water, it could be water righ...
Read more