Stretching Supplies in a Prior-Appropriation World

• Author: Adam Schempp
• Position: Staff Attorney and Director of the Western Water Program at the Environmental Law Institute
• Pages: 38-41

Page 38 ❧ THE ENVIRONMENTAL FORUM Copyright © 2010, Environmental Law Institute®, Washington, D.C. www.eli.org.

Reprinted by permission from The Environmental Forum®, July/August 2010

W ater always has been the lifeblood

of the western United States. But its

value is now greater than ever, and it

almost inevitably will continue to rise.

As populations increase, regional, na-

tional, and global demands for the region’s resources,

including water and products that rely on it, are also

growing. With more people come greater needs for

drinking, bathing, laundry, lawns, and parks. People

also demand groceries, energy, processed materials, ser-

vices, and recreation, most of which require water in-

puts. Additionally, the ecosystem services provided by a

healthy riparian environment, including water quality,

f‌lood protection, and water storage, depend upon suf-

f‌icient instream f‌lows. us, there are numerous de-

mands on water supplies but a lack of clear tradeof‌fs,

since humans appear to need them all.

Increasing water demands are not the only chal-

lenge. Greater uncertainty in water supply means an

ever-changing baseline for meeting those demands.

Climate change models predict an intensif‌ication of

the water cycle, producing longer droughts and more

substantial f‌loods. Rising temperatures already have

begun to cause earlier and more intense snowmelt, the

source of much of the West’s water, leaving less avail-

able for the late summer and fall if it cannot be cap-

tured. Additionally, recent data show that the average

annual f‌low of the Colorado River — a major source

for several western states — was overestimated at the

time the multi-state Colorado River Compact was

drafted, suggesting less supply in the future.

Increasing demand and uncertain, even declining,

supply necessitates f‌inding a way to do more with less

or else face very dif‌f‌icult tradeof‌fs. Generally speaking,

doing more with less water requires improving ef‌f‌icien-

cies in use and in supply management. Both approaches

require adapting policies to changing circumstances in

the short and long term, as well as aligning incentives,

f‌inancial and otherwise, with preferred practices.

A number of legal and non-legal factors contribute

to the state of water management, but the prior appro-

priation system, the predominant legal foundation for

water allocation in the West, is a critical consideration

for ef‌fective change. While adaptable, prior appropria-

tion is rule-bound, founded on the historical order of

rights and quantity of usage. An imperfect understand-

ing of the amount of water historically consumed (as

opposed to what returns to the stream), coupled with

the preeminent rule that “thou shall not injure the

rights of other water users,” has fortif‌ied established

practices behind a series of legal barriers, posing a sig-

nif‌icant obstacle to improving ef‌f‌iciency in use.

Stretching

Supplies

in a Prior-

Appropriation

World

Recent experience and most forecasts

suggest that the West will face

unprecedented water management

challenges in the coming decades. If the

objective is doing more with less, the law

should allow and indeed support that end

re s e a r c h a n d Po l i c y sT u d i e s

Adam Schempp is is a Staff Attorney

and Di rect or of the Wes tern Wa ter

Pro gram a t t he Envi ronm enta l L aw

Institute.