The era of dams, it has been widely declared, is
dead. So what comes next? In Common Waters, Diverging
Streams, William Blomquist, Edella Schlager and Tanya
Heikkila argue that the future may lie with “conjunctive
management,” or coordinating the use and storage of surface water
with water in underground aquifers. When surface water is
plentiful, excess water can be stored underground, for use later
when surface water is not so plentiful. The concept offers one of
the most promising means for increasing reliability, and, by
providing water users with “banked” groundwater for dry years, it
can help protect natural stream flows.
This is not just a
theoretical concept: Blomquist, Schlager and Heikkila focus on
Colorado, Arizona and California, where conjunctive use has been
practiced for decades. Each state has widely differing strategies
and goals for conjunctive management. In Colorado, for example, the
practice is most frequently used to maintain flows in surface
streams, both to meet water obligations to downstream states and to
protect endangered species habitat. In Arizona, it has become an
integral part of the state’s groundwater management act and
helps developers shore up the 100-year “assured supplies” required
for their housing projects. The authors examine the legal
frameworks that make conjunctive management work, those that
don’t, and the evolving effort to fine-tune the concept.
After decades of pedal-to-the-metal groundwater “mining”
in the West, write the authors, “this rapidly developing region,
which finds it nearly impossible to build additional above-ground
water storage facilities, also rests atop a cavernous amount of
underground storage capacity … If ever need met opportunity, it
has happened in the case of conjunctive management in the West.”
This article appeared in the print edition of the magazine with the headline The best thing since dams: pouring water underground.
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