Water Planning for Growing Southwestern Communities - Design with the Desert: Conservation and Sustainable Development - page 271

to shortages of freshwater. Arizona, for example, has interest in seawater desalination due
to the potential to either pipe water inland or, more likely, enable exchanges to be made,
whereby more Colorado River is delivered into Central Arizona in exchange for funding
for desalinated water. No such long-term agreements are yet in place, and it may take years
for them to be formulated.
Desalting technology also has the potential to treat brackish water sources to potable
quality. Operation of the Yuma Desalting Plant is of interest to the CAP, the Metropolitan
Water District of Southern California, and the Southern Nevada Water Authority. Though
built to treat return flows from the Wellton-Mohawk Irrigation and Drainage District, the
plant could treat high-salt groundwater, as well. Economic and environmental considerations,
such as brine disposal, are key to operating this plant on a continuing basis. As in Arizona,
in New Mexico, where at least two-thirds of all groundwater is considered brackish, com-
munities are increasingly considering desalination as part of their future plans.*
Technology is a key consideration but clearly not the only consideration related to the
use of reclaimed water (highly treated wastewater) for potable use. The “Yuck Factor” is
clearly a key consideration. 13,14 While some communities have met significant resistance to
connecting reclaimed water to the potable water system, if only indirectly through recharge,
other communities have not. Orange County, California's Groundwater Replenishment
Project, and Cloudcroft, New Mexico's reclaimed water treatment both involve systems
that, albeit in different ways, mix highly treated reclaimed water into their potable water
systems. 5 Reclaimed water has long been used for outdoor watering. The purple pipes
associated with this use are common features of golf courses, school grounds, and parks.
They are also becoming part of communities plumbed with dual systems to individual
properties. Industrial uses and exchanges of effluent with farmers help to supplement
water supplies. And even where effluent is not used to supplement other supplies, effluent-
dominated riparian areas and created wetlands occur widely across the Southwest, such
as at the Tres Rios Wetlands in Arizona and the Prado Wetlands in California.
A way of gaining more water for potable needs as communities grow is through
conservation and/or diversification of individual water portfolios. Conservation, which has
been long practiced in the Southwest, reduces per capita consumption of water. Lower per
capita community water use means a given supply can be spread over more users, thereby
forestalling the need to secure additional supplies. There is significant opportunity to
water conservation, as evidenced by the conservation programs introduced in Las Vegas,
Nevada, and San Diego, California. † Although conservation is not something people
oppose, some who are concerned about the rapid pace of growth in their communities
question the value of conserving water if the conserved water is used to support growing
populations rather than ecosystems degraded by water pumping and diversions. ‡
Increased capture of rainwater or stormwater is another means of increasing the diversity
of water supplies available to a community. However, laws in several states recognize
that the hydrologic cycle prevails, and water taken from one location in the hydrologic
cycle means that there is less water for another location. Large-scale capture of rainwater
means less water flowing downstream in one form or another, and small-scale actions of
individual households can add up. Nevertheless, rainwater harvesting, whether passive
or active, is a means of substituting rainwater for pumped water delivered through a
* See, for example, Sandia National Laboratories, 10 McGavock and Cullom, 11 and Hill. 12
† See, as but one example in a series about San Diego's experience in implementing voluntary water conserva-
tion Lee and Gardner. 15
‡ For a discussion of a way of connecting concerns with the environment and conservation, see Schwarz and
Megdal. 16