International Water Resources Association
Water International, Volume 25, Number 1, Pages 3–10, March 2000
3
Sustainable Water Resources Management
Daniel P. Loucks, Member IWRA, Cornell University, Ithaca, New York, USA
Abstract: Defining and measuring sustainability is a major challenge. This article argues these limi-
tations need not stop us from trying to identify and value the possible impacts of what we are doing, or are
thinking about doing, over time periods much longer than the lives of our investments, or even of the lives
of those of us living today. Sustainability is a relative concept that must be applied in an environment
undergoing multiple changes, changes that are occurring over different temporal and spatial scales. We
depend on our water resource systems for our survival and welfare. Yet no one expects them to be re-
stored to, or survive in, their most productive pristine states in the face of increasing development pres-
sures for land in their watersheds and for water in their streams, rivers, lakes, and aquifers. A continuing
task of water resource planners and managers is to identify the multiple impacts and tradeoffs resulting
from what we who are living today may wish to do for ourselves and our immediate children and what we
can only guess our yet-to-be-born descendants may wish us to do, or not do, for them in some distant
future. This task must involve professionals from other disciplines in a context much broader than just
water management. Once these impacts and tradeoffs are identified, it is then up to the political process
to make choices when they are in conflict. All of us need to be a part of this decision-making process.
Keywords: Sustainability, water management, risk, change, technology, sustainability guidelines,
scale, training.
Introduction
Sustainable water resources management is a concept
that emphasizes the need to consider the long-term future
as well as the present. Water resource systems that are
managed to satisfy the changing demands placed on them,
now and on into the future, without system degradation,
can be called “sustainable.”
Sustainable water resource systems are those designed
and managed to fully contribute to the objectives of
society, now and in the future, while maintaining their
ecological, environmental, and hydrological integrity
(ASCE, 1998; UNESCO, 1999).
Just how can water resources management be sustain-
able when we cannot look into the future with any degree
of certainty? We do not know with certainty what all the
impacts of even our current decisions will be. We do not
know what future generations of individuals or societies
will want or value. Nevertheless, we still need to consider
what we think they will be as we develop plans, designs,
and policies for managing our water resources. If success-
ful, these plans, designs, and policies should help us sat-
isfy not only our immediate demands and desires, but those
of future generations as well.
Sustainability is intimately related to various measures
of risk and uncertainly about a future we cannot know,
but which we can surely influence. Our guesses about the
future, with certainty, will be wrong. Hence they will need
to be revised periodically. Recognizing that some man-
agement objectives will change over time, we must con-
sider the adaptability or robustness of the systems we
design and operate today to this management uncertainty
and to the inevitable changes in the quantity and quality
of the resource being managed.
Because sustainability is a function of various eco-
nomic, environmental, ecological, social, and physical
goals and objectives, water resources management must
inevitably involve multi-objective tradeoffs in a multi-
disciplinary and multi-participatory decision-making pro-
cess. I believe no single discipline, and certainly no single
profession or interest group, has the wisdom to make these
tradeoffs themselves. They can only be determined
through a political process involving all interested and
impacted stakeholders. The participants in this process
must at least attempt to take into account the likely pref-
erences of those not able to be present in this decision-
making process, namely those who will be living in the
future and who will be impacted by current resource
management decisions.
In this paper, taken from a recent report on this sub-
ject (ASCE, 1998; UNESCO, 1999), I attempt to identify
some of the major issues and challenges raised by the
concept of sustainability applied to water resources man-
agement and to review ways we can respond to the two
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