202 R. W. Buddemeier et al.
the quantity and quality of local ground and surface water resources and their
interactions, and on the effects of pumping on water quality and on streamflow
into the Quivira National Wildlife Refuge.
Northern Stafford County. This region, a focus of intensive study between 1992
and 1996 (Young et al. 1996), extends from the initial sub crop of the Permian
fonnation in the vicinity of Highway 281 to the discharge region associated with
the Quivira National Wildlife Refuge (see Fig. 2). It is approximately bounded by
Rattlesnake Creek on the south and the Barton County line on the north. In the
western part of the region there is very high salinity deep in the alluvial aquifer,
although in many areas fresh water can be pumped from above a clay semiconfining layer. Farther east, freshwater resources diminish both in quantity and in
quality. Salt-water upconing due to pumping is a localized problem in the west,
and increasingly common to the east.
An extensive field study in northern Stafford County was made with the
cooperation of Mr. Dennis Siefkes, landowner (Young 1995; Young et al. 1995a,
1996). The study site is centered on an irrigation well that becomes progressively
saltier during the pumping season. A number of existing stock, domestic, and oil
field supply wells within approximately one-half mile of the irrigation well
provided a network of shallow and intennediate-depth monitoring points. In
addition, monitoring wells were installed and completed in the Permian bedrock
and at the base of the alluvial aquifer in the vicinity of the irrigation well.
Generally, the following groundwater aquifer system components can be
identified in the vicinity of the study site: (1) a freshwater aquifer extending to a
depth of about 45 m, (2) a deep aquifer, which is separated from the shallow
aquifer by a clay layer or lenses of variable thickness (about 3 m thick at the
Siefkes irrigation site); and (3) the Permian zone, which has low penneability and
is saturated with salt water. The Siefkes site study has provided a substantial
amount of infonnation about the characteristics of the aquifer system in that
region.
At the Siefkes site, and by inference throughout the region, the connection
between the deep aquifer and the Permian zone appears good, so every decrease of
the piezometric head in the deep aquifer leads to intrusion of salt water from the
Permian zone. Mitigation or prevention of salt-water penetration from the deep
aquifer into the shallow freshwater aquifer is a major concern. While there is good
connection between the deep aquifer and the Permian zone, the hydraulic
conductivity of the Permian zone is comparatively low. Table 1 summarizes the
results of hydraulic conductivity studies in northern Stafford County and
hydrogeologically similar areas ofGMD5.
the quantity and quality of local ground and surface water resources and their
interactions, and on the effects of pumping on water quality and on streamflow
into the Quivira National Wildlife Refuge.
Northern Stafford County. This region, a focus of intensive study between 1992
and 1996 (Young et al. 1996), extends from the initial sub crop of the Permian
fonnation in the vicinity of Highway 281 to the discharge region associated with
the Quivira National Wildlife Refuge (see Fig. 2). It is approximately bounded by
Rattlesnake Creek on the south and the Barton County line on the north. In the
western part of the region there is very high salinity deep in the alluvial aquifer,
although in many areas fresh water can be pumped from above a clay semiconfining layer. Farther east, freshwater resources diminish both in quantity and in
quality. Salt-water upconing due to pumping is a localized problem in the west,
and increasingly common to the east.
An extensive field study in northern Stafford County was made with the
cooperation of Mr. Dennis Siefkes, landowner (Young 1995; Young et al. 1995a,
1996). The study site is centered on an irrigation well that becomes progressively
saltier during the pumping season. A number of existing stock, domestic, and oil
field supply wells within approximately one-half mile of the irrigation well
provided a network of shallow and intennediate-depth monitoring points. In
addition, monitoring wells were installed and completed in the Permian bedrock
and at the base of the alluvial aquifer in the vicinity of the irrigation well.
Generally, the following groundwater aquifer system components can be
identified in the vicinity of the study site: (1) a freshwater aquifer extending to a
depth of about 45 m, (2) a deep aquifer, which is separated from the shallow
aquifer by a clay layer or lenses of variable thickness (about 3 m thick at the
Siefkes irrigation site); and (3) the Permian zone, which has low penneability and
is saturated with salt water. The Siefkes site study has provided a substantial
amount of infonnation about the characteristics of the aquifer system in that
region.
At the Siefkes site, and by inference throughout the region, the connection
between the deep aquifer and the Permian zone appears good, so every decrease of
the piezometric head in the deep aquifer leads to intrusion of salt water from the
Permian zone. Mitigation or prevention of salt-water penetration from the deep
aquifer into the shallow freshwater aquifer is a major concern. While there is good
connection between the deep aquifer and the Permian zone, the hydraulic
conductivity of the Permian zone is comparatively low. Table 1 summarizes the
results of hydraulic conductivity studies in northern Stafford County and
hydrogeologically similar areas ofGMD5.