Wetlands in the Farmington Bay Area, Davis County, Utah: An evaluation of Threats Posed by Ground-Water Development and Drought
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Resource ID
8378
Resource Type
Document
Availability
Public
UGS Program
Wetlands
Title
Wetlands in the Farmington Bay Area, Davis County, Utah: An evaluation of Threats Posed by Ground-Water Development and Drought
Author
Charles E. Bishop, Mike Lowe, Janae Wallace, Richard L. Emerson, and J. Scott Horn
Publisher
Utah Geological Survey
Date
-
Publication Identification
Report of Investigation 264
Country
USA
Keywords
wetland, farmington bay, great salt lake, ground-water, development, drought, monitoring, assessment, EPA, core element, water quality, hydrology, UGS, Utah Geological Survey
Document Type
Report
Original Filename
WTLND0070.pdf
Geotechnical Database
Not Included
Abstract / Description
ABSTRACT
The east shore area of Great Salt Lake in Davis County,
which contains the Farmington Bay wetlands, is in a formerly
rural area along the southeastern margin of Great Salt
Lake that is now largely urban and continues to undergo population
growth. Most of the development in the Farmington
Bay area uses municipal water sources, principally wells
completed in the east shore aquifer system, and some agricultural
wells continue to be used for irrigation and stock
watering. This population growth and concomitant increases
in municipal ground-water pumping could significantly
decrease the amount of ground water discharged from the
principal aquifer system (where most wells are completed) to
the shallow unconfined aquifer system.
The shallow unconfined aquifer overlies confining beds
above the principal aquifer system in the western part of the
east shore area, and provides water to springs and approximately
18,630 acres (7540 hm2) of wetlands in ground-water
discharge areas. Decreased recharge to the shallow unconfined
aquifer from the principal aquifer due to increased
ground-water pumping could reduce water supply to these
springs and wetlands. Also, water supply to the springs and
wetlands is affected by climatic conditions and Great Salt
Lake levels. Drought conditions during 1999-2004 reduced
the amount of recharge to ground-water aquifers across the
state, negatively impacting the Farmington Bay area wetlands.
In 2005, the elevation of Great Salt Lake declined to
near its historic lowstand reached in 1963, allowing some
parts of the Farmington Bay wetlands to dewater.
To evaluate the potential impacts of drought and
increased development on the Farmington Bay area wetlands,
we used existing data to estimate a water budget for
the wetlands area. To determine the potential impacts posed
by increased ground-water development and further drought,
we used two regional, three-dimensional, steady-state and
transient MODFLOW models for the east shore area of Great
Salt Lake to evaluate water-budget changes for the wetland
areas. The modeling suggests that subsurface inflow into the
wetland areas would be most affected by decreased subsurface
inflow due to long-term (20-year) drought conditions,
but subsurface inflow would also decrease due to increased
municipal and industrial well withdrawals over the same
time period. Therefore, the worst-case scenario for the wetlands
would be a combination of both conditions. As a conservative
goal, the Farmington Bay wetlands area should be
managed to maintain its current budget of water, which is
estimated to include at least 16,000 acre-feet per year (20
hm3/yr) of recharge as subsurface inflow.
This study indicates that wetlands in the Farmington Bay
area are endangered. The threats posed are from drought and
increased development due to population growth, which
could dramatically affect the amount of water the wetland
area receives. To reduce the potential for degradation of the
Farmington Bay wetlands, restrictions could be placed on the
areas of development, such as allowing development only in
upland environments or placing a non-development buffer
around the wetland areas. Wastewater from sewers could,
where possible, be reused or discharged to the environment
upgradient of the wetlands. Enactment of water conservation
practices would also be beneficial for the wetland environments.
Marker lat / long: 40.944475, -111.975849 (WGS84)