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Hydrology of the Upper Colorado River Planning Area - Groundwater (West Basins)

Click to view Figure 4.0-4

Figure 4.0-4 Surface Geology of the Upper Colorado River Planning Area

The Upper Colorado River Planning Area is characterized by semi-arid to arid alluvial basins with few perennial streams.  Anderson, Freethey and Tucci (1992) divided the alluvial basins in south-central Arizona into categories based on similar hydrologic and geologic characteristics.  These categories are useful in describing general hydrologic characteristics.  Although their study area does not match the Department’s groundwater basins exactly, the Upper Colorado River Planning Area is included in their study area with the exception of the Peach Springs Basin.  Four basin categories identified by Anderson are represented in the planning area and are discussed below: West, Colorado River, Highland and Southeast.

As shown in Figure 4.0-4, there are extensive outcrops of sedimentary and volcanic rocks of varying ages throughout the planning area. Large areas of basin-fill covered by alluvial and surficial deposits are found in the western part of the planning area, primarily in the West basins.

West Basins

The West basins include the Detrital Valley, Hualapai Valley, and Meadview basins, most of the Sacramento Valley Basin and part of the Bill Williams Basin (see Figure 4.0-2). Groundwater inflow and outflow are small and there is almost no stream baseflow.  These basins contain extensive areas of basin fill deposits that comprise the primary groundwater bearing unit (aquifer).

Detrital Valley Basin

The Detrital Valley Basin is characterized by a relatively long valley whose floor slopes from 3,400 feet at the southern boundary to around 1,200 feet at Lake Mead.  Groundwater occurs mostly in basin-fill material and in alluvial deposits along mountain washes.  Intermediate and younger basin fill are above the water table in most areas, consequently the older basin fill aquifer is the primary water supply.  In the northern part of the basin, the basin fill includes clastic (weathered) sediments, limestone, and basalt flows of the Muddy Creek and Chemehueve Formations. There are extensive evaporate deposits in the older alluvium in the northern part of the basin (Anning and others, 2007).   Depth to bedrock may exceed 6,000 feet at the deepest point.  A clay unit may extend from 600 to 1,400 feet below land surface (bls) in the central portions of the basin, which acts as an impediment to groundwater flow and reduces the amount of recoverable groundwater due to its low specific yield.  The areal extent of this unit is not well known due to lack of data (Mason and others, 2007).  Groundwater flow direction is north toward Lake Mead. At the northern end of Detrital Valley water from Lake Mead infiltrates to the basin-fill aquifer and near by groundwater levels fluctuate with the levels.  Depth to water may be less than 100 feet bls in this area (Anning and others, 2007).

Detrital Basin

Detrital Valley Basin.  The estimated volume of recoverable groundwater to a depth of 1,200 feet bls ranges from about 1.48 to 3.94 maf. 

Groundwater recharge is estimated at 1,000 AFA. Groundwater discharge is to springs and from relatively small well withdrawals for municipal purposes. The volume of recoverable groundwater to a depth of 1,200 feet bls is estimated to range from about 1.48 to 3.94 maf (Mason and others, 2007). The median well yield in measured wells is generally 35 gpm or less (Table 4.3-5).  As shown in Figure 4.3-6, groundwater levels were relatively stable in wells measured in 1990-91 and 2003-04, although water-level measurements for different time periods show long-term declines in an area northeast of Dolan Springs (Anning and others, 2007).  Water quality is suitable for most purposes although concentrations of radionuclides and arsenic that exceed drinking water standards have been measured at wells throughout the basin. (Table 4.3-6, Figure 4.3-9).

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Hualapai Valley Basin

The Hualapai Valley Basin trends north-northwest and is about 60 miles long, stretching from the Hualapai Mountains to Lake Mead. The basin has relatively deep, sediments divided into three units. The younger basin fill includes recent streambed deposits in Hualapai Valley and alluvium along mountain canyons.  This unit yields relatively small volumes of water to stock and domestic wells.  The intermediate basin fill, which is composed of coarse-grained sands, silts and clays, is a dependable aquifer only along the valley margins where the unit intersects the water table.  As with other basins in this category, the older basin fill is the primary water supply.  Similar to the Detrital Valley Basin located to the west, older basin fill in the northern part of the valley includes clastic sediments, limestone and basalt flows of the Muddy Creek and Chemehueve Formations.  Volcanic rocks are interbedded with the older basin fill in the southern part of the basin and yield water for municipal and domestic purposes. Groundwater flows into the central part of the basin from the south and along Truxton Wash near Hackberry (Figure 4.4-6).  Surface water collects in the Red Lake playa bear the center of the basin, whereas groundwater flows to the north underneath the topographic divide near Pierce Ferry Road (Anning and others, 2007).

Groundwater recharge comes primarily from streambed infiltration and is estimated at 2,000 to 3,000 AFA (Table 4.4-4).  Groundwater discharge is to several major springs and from relatively large volumes of well pumpage for municipal use by Kingman.  The well pumpage is are almost three times the estimated groundwater recharge rate. Groundwater in storage estimates range widely from 3 to 21 maf. Median reported well yields are relatively high at 900 gpm (Table 4.4-4). In the central and northern part of the basin groundwater levels were relatively stable or rising between 1990-91 and 2003-04 while water levels were declining in the southern part of the basin (Figure 4.4-6). Water-level measurements over longer time periods show fluctuating water levels in the basin with long-term declines found in the area northwest of Hackberry (Anning and others, 2007).  Groundwater is highly mineralized in some areas near the mountains and near Red Lake.  Chromium has been detected in some wells in the basin.

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Meadview Basin

The relatively small Meadview Basin is characterized by a valley formed by Grapevine Wash in the north, and a highland area, Grapevine Mesa in the south. The basin floor slopes toward Lake Mead from an elevation of about 4,400 feet to 1,400 feet. The main aquifer occurs in the Muddy Creek Formation  which contains three units.  The upper limestone unit yields water to springs and shallow wells.  The middle sandstone unit has a high clay content that limits its ability to transmit water.  The lower unit is a conglomerate with high hydraulic conductivity.  Most well development has been in this lower unit.  Groundwater flow is from south to north, following Grapevine Wash.

Groundwater recharge is relatively small, about 4,000 AFA, due to low rainfall and high evaporation rates.  Groundwater discharge is to springs and a relatively small volume of municipal well pumpage.  Groundwater in storage is estimated at 1.0 maf or less. The median measured well yield is 33 gpm (Table 4.7-5). There is little water level monitoring in the basin. Available data show water levels as deep as 931 feet bls in the southern part of the basin and declines of more than 15 feet have been measured in a well in the vicinity of Meadview during the period 1990-91 and 2003-04 (Figure 4.7-6). Groundwater quality is generally good in the basin, with elevated concentrations of radionuclides measured primarily in or near granitic areas (ADEQ, 2005).

Colorado River, Sacramento Valley Basin

Colorado River, Sacramento Valley Basin.  Groundwater recharge is from infiltration of runoff in washes and along mountain fronts, except in the vicinity of the Colorado River where infiltration of river water is the main source of recharge.

Sacramento Valley Basin

Sloping alluvial fans extend from surrounding mountains to the north-south trending valley floor of the Sacramento Valley Basin. The valley floor generally slopes to the south with elevation ranging from more than 8,400 feet at Hualapai Peak to about 500 feet where Sacramento Wash enters the Colorado River. Older basin fill is the principal aquifer in the basin. There are fractured and faulted volcanic rocks in the vicinity of Kingman that separate this basin from the Hualapai Valley Basin. Water stored in the fractures is used as part of the municipal water supply for Kingman and for domestic wells. The fractured granite aquifer beneath the community of Chloride is insufficient to meet its needs and water must be hauled from Kingman. Groundwater flow is toward the center of the Sacramento Valley and west to the Colorado River.

Groundwater recharge is from infiltration of runoff in washes and along mountain fronts, except in the vicinity of the Colorado River where infiltration of river water is the main source of recharge. Groundwater recharge is estimated at 1,000 to 4,000 AFA. Groundwater discharge is to a number of springs and from municipal and industrial well pumpage.  Groundwater in storage estimates range from 7 to 14 maf.  Recent investigations using a range of specific yield values estimated 3.6 to 9.5 maf of groundwater in storage to a depth of 1,200 feet bls (Conway and Ivanich, 2008). Median well yields are between 100 and about 170 gpm (Table 4.9-6).  Groundwater levels may be relatively deep with depths greater than 500 feet measured at several locations. Water levels declined in measured wells in the vicinity of Kingman and east of Topock between 1990-91 and 2003-04 (Figure 4.9-6).  Water-level measurements over longer time periods show fluctuating water levels in the basin with long-term declines in the Kingman area and Golden Valley area (Anning and others, 2007). 

Groundwater quality is generally good in the basin except along the base of the mountains where waters of high mineral content are common. A study conducted by ADEQ found water quality exceedences in the majority of sample sites in three areas: near the town of Chloride; in the central and southern Hualapai Mountains; and near the town of Topock (ADEQ, 1999). Concentrations of radionuclides in Chloride town wells have exceeded Safe Drinking Water Act maximum contaminant levels (City of Kingman, 2003). 

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Bill Williams River

Bill Williams River, Bill Williams Basin.  Well Yields may exceed 2,000 gpm along the Bill Williams River.

Bill Williams Basin (western portion)

Anderson, Freethey and Tucci (1992) categorized most of the western portion of the Bill Williams Basin as a “West” basin, which generally corresponds to the Alamo Reservoir and Clara Peak sub-basins (see Figure 4.2-6).   The area in the vicinity of the Colorado River is influenced by infiltration of river water. Groundwater in the western part of the basin occurs primarily in recent stream alluvium and basin fill.  The water-bearing ability of these units varies within the basin.  The stream alluvium consists of gravel, sand and silt along the Bill Williams River and its major tributaries.  The main water-bearing unit is the basin fill, which is more than 5,000 feet thick in the Bullard Wash-Date Creek Area southeast of Alamo Lake State Park.  Groundwater flow is toward the Bill Williams drainage.

Groundwater recharge is from streamflow and mountain front precipitation and is estimated at 32,000 AFA for the entire basin.  From 10 to 23 maf of groundwater is estimated in storage. There is little groundwater development in the western portion of the basin and relatively little groundwater level data (see Figure 4.2-6).  Available water level data show stable water levels.  Well yields may exceed 2,000 gpm along the Bill Williams River. Arsenic and fluoride concentrations that exceed drinking water standards have been reported from this portion of the basin as well as elevated levels of cadmium near the mouth of the Bill Williams River. 

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