Colorado Water April 2005

• Year: 2005
• Title: Colorado Water
• Author: Water Center of Colorado State University
• Description: April 2005
• Publications - Doc Type: Newsletter

Understanding Ground Water
by Robert C. Ward
Director, CWRRI
The incorporation of ground water into a conjunctive man-
agement relationship with surface water has been occurring
in the Western U.S. for a number of years. Tellman (1994)
described the variety of conjunctive ground and surface water
management systems employed in the U.S. She noted, in
particular, that each state has a unique program that is under-
going development over time.
Recent events in Colorado (e.g. court cases, drought, new
legislation, and compact settlements) are spurring rapid
evolution in the way Colorado conjunctively manages surface
and ground water. Managing ground water in a
sustainable relationship with surface water, in the
real world, is multifaceted and complex. The effects
of human activities, and how these effects transmit
themselves through the hydrologic system, need to be
better understood.
In this issue several articles describe research that
improves our understanding of ground water quality
and quantity. On page 14, Dano, Poeter, and Thyne
describe the role of septic tank effluent in the degra-
dation of the Turkey Creek Basin's water quality by
investigating the flow path and chemical evolution of
the effluent after it leaves the infiltration area of one
individual sewage treatment system. The chemical
fingerprint of the effluent is similar to the surface water near
the mouth of the basin suggesting that the effluent contributes
to decreased water quality.
Hirsch further notes that ground -water depletion can have
negative consequences for streamflow, riparian vegetation,
land - surface subsidence, water quality, water temperature,
flow to wells, and the quality of life for future generations.
To understand and manage for sustainable ground -water use,
it is crucial to understand ground- water /surface -water interac-
tions and subsequent effects on biota. To obtain this under-
standing requires well- designed monitoring programs and
computer models that can accurately simulate both ground-
water and surface -water flow systems, with some additional
paradigm shifts, as outlined below.
On page 10, Miller and Durnford examine questions sur-
rounding use of the Stream Depletion Factor (SDF) method
to assess stream depletion and accretion caused by ground
water pumping and recharge. In the case studied, it is con-
cluded that the SDF maps remain a widely available refer-
ence for use at sites where there is limited data.
At the recent AWRA Water Policy Dialogue in Tucson,
Arizona, Bob Hirsch, Associate Director for Water, U.S.
Geological Survey, discussed water availability being
complicated by depletion of ground water in storage. In his
presentation (provided on page 30 of this issue of Colorado
Water) he noted that current levels of water use in many parts
of the country are dependent on withdrawing ground water at
rates that exceed average recharge. As the amount of water
in storage in aquifers decreases and the vertical distance wa-
ter must be pumped to the land surface increases, the overall
availability of ground water decreases.
On page 4, Garcia updates Colorado Water readers on
developments with the South Platte Mapping and Analysis
Program ( SPMAP) — a set of software tools being used to
establish augmentation plans for wells along the South Platte
River. SPMAP provides the type of science that Hirsch
notes, above, is needed. Development of SPMAP has been
underway for a number of years, but the true value of this
research effort became painfully obvious as the drought of
2002 unfolded. The SPMAP article provides an overview of
the history of the research and insight into recent efforts to
improve the ET estimation module.
Before closing, I must note that on page 13 Susan Hyatt,
Development Officer for the Morgan Library at CSU, reports
that the campaign to raise funds to remove mold from the
Delph Carpenter Collection in the CSU Water Archives has
reached its target. This brings the Carpenter Papers closer to
public access.
References
Tellman, Barbara. 1994. My Well v. Your Surface Water Rights:
How Western States Manage Interconnected Groundwater and
Surface Water. Issue Paper 15, Water Resources Research Center,
University of Arizona, Tucson, Arizona.
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