WSP05845

• File Number: 8507
• Description: Rio Grande Project
• State: CO
• Basin: Rio Grande
• Date: 7/1/1997
• Title: Water Management Study: Upper Rio Grande Basin part 2
• Water Supply Pro - Doc Type: Report/Study

Water Management Study: Upper Rio Grande Basin

the ecosystem. The same observation applies to groups who have engaged in
other resource-manipulation activities, including but not limited to
urbanization, forest management, grazing, and road construction.

Failure to account for the ecosystem effects of individual resource-
management activities has important implications for the competition for
scarce water and related resources. In particular, it alters the supply of
individual resources and increases the scale and scope of the spillover effects
from each resource use. An extensive body of research shows that making
resource-management decisions focusing on a single resource, such as water
flows, can have wide-ranging and persistent effects throughout the
ecosystem (Doppelt et al. 1993; Pacific Rivers Council 1996). These effects
on the ecosystem can, in time, have feedback impacts on the resource itself,
by altering the quantity and quality of the water, for example. They also are
likely to impose wide-ranging and persistent costs on specific individuals and
groups, and on the local, regional, and national economies.

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Diverting a little water from the river for a short period of time might have
little effect on the ecosystem and, hence, on the full set of goods and services
humans derive from it. Diverting all the water for a long time, however, has
had profound impacts on the ecosystem, especially when linked to correlated
activities, such as draining of wetlands, altering of the hydrograph, and
channelizing of the river bed,

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The following statements, taken from the Bosque Biological Management
Plan for the Middle Rio Grande (Crawford et al. 1993a) illustrate the
impacts of past and current management activities on the ecosystem:

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. Hydrology is the primary factor influencing Middle Rio Grande aquatic
habitat. ... Historically, the Middle Rio Grande has maintained
periods of high, flooding flows and low, dessicating flows. ... Native
aquatic species have adapted to survive these conditions until high
flows reestablish habitat continuity and availability. Human influence
often exacerbates the impacts of natural disturbances. The introduction
of a water regulation infrastructure in the Middle Rio Grande has
increased the potential for longer and more frequent periods of low flow
and habitat fragmentation. The extent of channel dessication due, in
part, to water regulation has been identified as a causative factor in the
decline and extirpation of several Middle Rio Grande fish species
[citations omitted].

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