Chapter 3 of the main body of the report is titled "Sustainable Water Future." The first question that pops into my mind - What is meant by "sustainable water future"? The term sustainable is imbued with so many value judgments that it really can have no fixed meaning. In fact this was a question that the committee wrestled with pretty extensively during the final set of meetings. This point was discussed at some length in the Executive Summary, specifically mentioning that while there was some agreement among the committee as to the facts associated with the "data" considered and condensed within Phase I of the study and how they are applied in the context of sustainability, some of the harder-to-define aspects of sustainability (i.e. what is a sustainable population for the region) that rely heavily on various assumptions about shared values produced varying opinions among the committee, which will be explored further in Phase II.
As for this Chapter of the report, it starts with a discussion of a scenario-building exercise conducted by the Water Resources Research Center that attempted to determine the total population that could be supported by the known, existing water supplies available in the Tucson region, in the year 2030 (they looked at the county as a whole, not just Tucson or the Tucson Water service area). These population predictions necessarily involved numerous assumptions about availability of water sources (such as Colorado River water), per capita water usage, and future use of effluent to supplement water supplies. Because of these assumptions it is not a crystal ball - it merely considers several possible future outcomes. This exercise, along with the Tucson Water 50 year plan, forms the basis of much of what the committee looked at in this portion of the report.
The 50 year plan (also updated last year) explores various scenarios for future population growth and looks at the various management options for Tucson Water to supply that population with water and retain its Assured Water Supply (pdf document) designation. These scenarios involve permutations of maximum CAP allocation usage, increased effluent reuse (either directly or indirectly), and conservation programs to reduce per capita use. Essentially they are asking - How far will our existing supplies take us under these different scenarios? The upshot of this being, that unless we either find new supplies, make greater use of effluent, or further reduce per capita usage (or some combination of those) we will be hitting some limits with our supplies around 2020, which is not that far off. This is with a potential population in the Tucson Water service area of slightly under 1 million people (the current number is around 650,000 - I think, while total population in the region is about 1 million currently).
So, even assuming our Colorado River supplies remain intact through that time (probably a pretty safe assumption, but maybe not), this community has some tough choices to make in the near future. Oh, and I have been completely forgetting about water for the environment, which was noted by the committee as an important aspect of a sustainable water future. I'm definitely in favor of using some water to restore riparian ecosystems in the area, but I suspect that what will actually happen and what some of the more vocal proponents of water for the environment would like to see are some considerable distance from each other. Talking to some people of the "slow to no growth and much more water for the environment" persuasion I get the impression that they want to see flowing rivers in Tucson at some point in the future. I'm afraid that discussion needed to happen a long time ago, unless they're perfectly content with effluent-dependent waterways below sewage treatment facilities (that's very do-able). This is a key value judgment that needs to be made by this community with a lot of good data about economic trade-offs and realistic expectations of what can be achieved. Not an easy task by any means.
Finally, as what I perceive to be a prelude to Phase II of the study, the report discussed the issue of land use planning and the need that it be informed by realistic water supply information. This section was in some respects a re-hash of previously discussed data on water and wastewater infrastructure but put in the context of land use decision-making. It was a very matter-of-fact discussion outlining the need for greater regional cooperation on planning and discussions on community values that should be involved in future growth planning (see my previous posts on this topic here and here). Both of those ideas are essential, I believe, to a meaningful discussion during Phase II of the study. And that segues nicely to where my next post on the report will pick up - Vol. 2, Section 4 - Recommendations for Phase II of the study. I haven't looked at that section at all yet, so I'll have to see how my comments regarding Phase II sync with those of the committee.
I think that will be my final post on the report. The public comment period on the draft ended last week, so I blew that deadline, but it sounds like the final report won't be submitted to mayor and council until April so there may be additional opportunities for comment between now and then.