|
Northwest Arizona Watershed Council
Hualapai Valley Basin
The Hualapai Valley basin is in northwestern Arizona and
contains 1,820 square miles. The
basin is bounded on the west by the Cerbat and White Mountains, on the east by
the Grand Wash Cliffs and Music Mountains, on the south by the Peacock and
Hualapai Mountains, and on the north by Lake Mead.
Elevations range from 1,300 feet above mean sea level
along the valley floor to 7,150 feet above mean sea level in the Cerbat
Mountains and 6,500 feet above mean sea level along the Grand Wash Cliffs.
The Hualapai Valley basin-fill sediments range to as much
as 6,400 feet thick (Oppenheimer and Sumner, 1980), and have been divided into
three separate units: a younger alluvium, an intermediate alluvium, and an older
alluvium (Gillespie and Bentley, 1971).
The younger alluvium includes streambed deposits in
Hualapai Valley and in various mountain canyons. The unit seldom exceeds 50 feet in thickness, and is composed
of silt to gravel-sized particles. The
younger alluvium yields small amounts of water to stock and domestic wells in
mountain canyons (Gillespie and Bentley, 1971). The igneous and metamorphic rocks, volcanic rocks, and
Paleozoic sedimentary rocks are generally non-water bearing. However, fractured and weathered zones in these rocks do
provide some water to low-yield wells, and numerous springs and seeps.
In the central part of the valley, the younger and
intermediate alluvium are above the water table, and therefore, dry. The intermediate alluvium is a dependable aquifer only along the valley
margins where the unit intersects the water table. Well yields from the intermediate alluvium range up to 500 gallons per
minute (Gillespie and Bentley, 1971). The
intermediate alluvium is made up of coarse-grained sands, silts, and clays.
The older alluvium is the main aquifer in the Hualapai
Valley basin. Volcanic rocks are
interbedded with the older alluvium in the southern part of Hualapai Valley and
form a secondary system (Cella Barr Associates, 1990). The
older alluvium can store and transmit large amounts of water; well yields up to
1,500 gallons per minute have been reported (Remick, 1981). Depth to water ranges from 500 to 900 feet below land surface in the
central and southern parts of the basin to 300 feet below land surface near Red
Lake (Remick, 1981).
Although the Hualapai Valley basin is sparsely populated,
5,000 acre-feet of groundwater were withdrawn from it in 1984 (U.S. Geological Survey, 1986). The
City of Kingman has a well field in the southern portion of the valley near the
airport that is responsible for most of the withdrawals. The remainder of the pumpage is for stock and domestic uses by the
ranches and settlements in the valley. Withdrawals
by Kingman alone exceeded 6,000 acre-feet in 1989.
Schmidt and Associates (1993) reported water level
declines in the southern part of Hualapai Valley. A well at the southwest edge of the airport had a recorded
water level decline of 1.0 feet per year for the period 1986 to 1992. The greatest water level decline recorded was 2.0 feet per year between
1980 and 1991 in a well about three miles northwest of the airport. The average water level decline rate for the basin is 1.4 feet per year
(Arizona Department of Water Resources, 1994).
Small water level declines have been recorded over the
rest of the Hualapai basin due to the undeveloped nature of the groundwater
resources (Celia Barr Associates, 1990). In
the vicinity of Hackberry, however, annual water level declines of up to seven
feet per year occurred during the 1960’s when the Hackberry wellfield was used
as a municipal water supply for Kingman. Municipal use of the wellfield was discontinued after 1969
and water levels near Hackberry have continued to recover (Celia Barr
Associates, 1990; Federal Energy Regulatory Commission, 1981).
Recharge to the valley aquifers is from streambed
infiltration. Recharge from
precipitation on the valley floor is negligible due to high evapotranspiration
rates. Freethey and Anderson (1986)
estimate that recharge is 4,000 acre-feet per year in the Hualapai Valley basin. Approximately 1,000 acre-feet of that total are underfiow from the
Hackberry area, and 3,000 acre-feet are from streambed infiltration (Freethey
and Anderson, 1986; Gillespie and Bentley, 1971). However, the Truxton Canyon Water Company’s well field may be
intercepting most of the underfiow from the Hackberry area (Remick, 1981). Actual net recharge into the basin may be only 3,000 acre-feet per year.
Groundwater moves from the mountain fronts towards the
center of the valley, then flows north and exits the basin as underfiow to Lake
Mead (Gillespie and Bentley, 1971). Hualapai
Valley is probably in a state of limited groundwater depletion. Outflow is probably between Remick’s (1981) estimate of 2,500 acre-feet per year and Freethey and Anderson’s (1986) estimate of 4,000
acre-feet per year. Total
groundwater availability to 1,200 feet below land surface in the basin is
estimated to be 5,000,000 acre-feet (Freethey and Anderson, 1986; Arizona
Department of Water Resources, 1988).
The chemical quality of water from the older alluvium
aquifer in the Hualapai valley generally is good. Total dissolved solids range from 210 to 1,100 milligrams per
liter (mg/l); however, in some areas in or near the mountains groundwater is
highly mineralized. Total dissolved
solids in these areas ranges from 1,430 to 2,365 mg/l (Gillespie and Bentley,
1971). The recommended secondary
maximum contaminant level for total dissolved solids in drinking water is 500
mg/l (U.S. Environmental Protection
Agency, 1988). Fluoride
concentrations in water ranged from 0.1 to 6.5 mg/l (Remick, 1981). High
concentrations of sodium chloride may occur in wells near the salt deposit in
the area of Red Lake.
Chromium has been detected in several of the water
production wells operated by the City of Kingman in the airport area (Cella Barr
Associates, 1990; Schmidt and Associates, 1993). In 1982, eight of ten known wells drilled in the airport
area contained chromium in excess of the maximum contaminant level of .05 milligrams per liter (Celia Barr Associates, 1990). In 1992, the maximum contaminant level for chromium was raised to .10
milligrams per liter; all of the water sample results for the City of
Kingman’s airport area production wells were then under the new maximum
contaminant level for chromium (Schmidt and Associates, 1993). Prior water quality studies have noted an increase in chromium below a
depth of about 1,000 feet.
Sacramento Valley Basin
The Sacramento Valley basin covers about 1,400 square
miles in western Arizona. The
entire basin falls within the Basin and Range province. The basin trends in a north-south direction and is bounded on
the west by the Black Mountains, on the southwest by the Mohave Mountains, and
on the east by the Cerbat and Hualapai Mountains. Elevations range from 8,417 feet above mean sea level at Hualapai Peak to
about 500 feet above mean sea level where the Sacramento Wash joins the Colorado
River near Topock.
The older alluvium is the principal aquifer in the
Sacramento Valley basin. Unconfined
conditions are predominant in the aquifer which has an approximate areal extent
of 500 square miles. The
recoverable groundwater in storage to 1,200 feet is estimated to be 7 million
acre-feet (Arizona Department of Water Resources, 1988). Depth to water ranges from over 1,000 feet below land surface in the
northern part of the basin north of Highway 68 to less than 100 feet below land
surface where the Sacramento Wash enters the Colorado River valley (Rascona,
1991). Saturated thicknesses ranged
from 0 to 600 feet (Arizona Department of Water Resources, 1988).
Groundwater declines have occurred in the former Duval
Corporation well field south of Highway 68. Now owned by Cyprus Metals Company, this well field exhibits average
groundwater level declines of 0.8 feet per year (Arizona Department of Water
Resources, 1994). In the Golden
Valley area, north of Highway 68, groundwater levels declined 26 feet (an
average of 1.2 feet per year) during the period 1979 to 1991. These declines are due to groundwater withdrawals associated
with the steady increase of population and the Cyprus Metals Company well field
to the south. In 1990, about 370
acre-feet of groundwater was withdrawn from this area north of Highway 68. Little to no water level decline has been recorded in the remainder of
the basin (Rascona, 1991; Schmidt and Associates, 1993).
The groundwater in the Sacramento Valley basin generally
is of good chemical quality. However,
the groundwater located along the base of the mountain ranges tends to have a
high mineral content. Total
dissolved solids in the range of 1,400 to 2,400 milligrams per liter were
reported in samples from areas in and near the Cerbat Mountains (Gillespie and
Bentley, 1971). All other chemical
constituents within the water are within drinking water standards.
The amount of groundwater pumped from the aquifers has
varied over the years. It has
ranged from 6,000 acre-feet per year from 1964-1980 to about 2,000 acre-feet per
year from 1981-1986 (Steve Rascona, personal commun., 1991). The decline in water use represents the reduction in mining activity at
the Mineral Park Mine in the 1980’s. Cyprus
Metals Company acquired the Mineral Park Mine from the Duval Corporation in
1986; annual groundwater pumpage has ranged from 400 acre-feet in 1986 to 600
acre-feet in 1990. Although the
open pit copper-molybdenum mine and concentrator were on standby in 1989, the
precipitation plant has begun operating (Arizona Department of Mines and Mineral
Resources, 1988). Water use is
expected to increase as the mine becomes more active. Cyprus Metals Company owns the five former Duval wells which have yields
of up to 1,000 gallons per minute. Residential
water use has been increasing steadily with the population growth in the Golden
Valley area. Most wells in the
basin are low yield stock and domestic wells. No irrigation wells are present.
The City of Kingman is the main population center in the
Sacramento Valley basin, A small portion of the City is on a ridge of fractured
and faulted volcanic rocks separating Sacramento Valley and Hualapai Valley
basins and a large portion is on the alluvial fill of Hualapai Valley basin. Kingman has developed a well field at the southern end of the Hualapai
Valley basin to provide a dependable, long-term source of water supply. The 1989 demand of the City was about 6,000 acre-feet; 450 acre-feet of
groundwater were pumped from wells completed in volcanics of the Sacramento
Valley basin. In addition to
groundwater, the City of Kingman has an available supply of 18,500 acre-feet per
annum of Colorado River water under a valid and unused 1968 contract.
The Town of Chloride has been experiencing a severe water
shortage and hauls water from Kingman to supplement their needs. Groundwater pumped from fractured granite in the area is insufficient to
meet Chloride’s needs, and repeatedly exceeds the maximum contaminant level
established for radionuclides.
The principal aquifer receives most of its recharge by
infiltration of runoff into the alluvium of the washes and along the mountain
fronts. Gillespie and Bentley
(1971) estimated that 4,000 acre-feet of water per year are recharged to the
main aquifer. Surface discharge
from the Sacramento Wash is estimated to be about 500 acre-feet per year
(Gillespie and Bentley, 1971).
Big Sandy Basin
The Big Sandy basin consists of approximately 1,900
square miles in northwest Arizona. It
is bounded by the Hualapai Mountains to the west, the Mohon Mountains to the
south, the Juniper Mountains to the east, and the Peacock Mountains and
Cottonwood Cliffs to the north. The
Aquarius Mountains run north-south and divide the Basin and Range province to
the west from the Central Highlands province to the east. Land surface elevations in the mountainous areas range from
5,000 feet above mean sea level in the Aquarius Mountains in the central part of
the basin to a maximum altitude of 8,417 feet above mean sea level at Hualapai
Peak in the Hualapai Mountains to the west.
Groundwater occurs in three hydrologic settings: in the
floodplain alluvium and upper basin-fill found along the central valley, and in
the sedimentary rocks found in the extreme northeastern part of the area.
The floodplain alluvium generally is 30 to 40 feet thick. This unit is an unconsolidated deposit of gravel and sand that underlies
the streams and floodplains. Wells
greater than 40 feet deep that tap the stream and floodplain alluvium along the
Big Sandy River near Wikieup also tap the upper basin-fill. These wells, if properly constructed, can yield as much as 1,000 gallons
per minute. As of 1980, there had
been no significant changes in water level in the unconsolidated deposits.
Most of the groundwater development has been along the
central valley where one of the main water-bearing units is the upper
basin-fill. These deposits vary
from a loosely-consolidated silty gravel to a sandy silt. The thickness of the upper basin-fill is estimated at 150 to
200 feet in the northern part of the area and about 300 feet near Wikieup and
Natural Corrals Wash. The upper
basin-fill receives recharge from streamfiow during most of the year. It is estimated that the upper basin-fill is capable of yielding as much
as 1,000 gallons per minute of water to wells (Davidson, 1973).
In the east-northeast portion of the Big Sandy basin, a
sedimentary layer composed of the Redwall Limestone and the Martin Formation
(Arizona Bureau of Mines, 1958) may be a regional aquifer which extends to
adjacent areas to the north and the east (Cady, 1981). in the area of the Big Sandy basin where this unit is present, the depths
to water range from 32 feet below land surface in the east near Buck Dam to a
reported 950 feet below land surface in the northern part of the basin, just
south of Rubel Ranch. There are
very few wells in this area, therefore, the areal extent of the aquifer cannot
be determined.
The Hackberry area, in the north-northeast portion of the
basin, is experiencing long-term declines of 1 to 2.5 feet per year (Gillespie and Bentley, 1971; Remick, 1981).
The dissolved-solids concentrations in the Big Sandy
basin range from 282 milligrams per liter (mg/l) in the basin-fill southwest of
the Peacock Mountains to 2,460 mg/l in Antelope Wash, northeast of the Hualapai
Mountains. Fluoride concentrations
in this area range from 0.2 mg/l in the Mohon Mountains to 20.0 mg/l along the
edge of the basin- fill, east of Hualapai Peak. Overall, the quality of the groundwater in the Big Sandy basin is good,
however, the groundwater in much of the area contains fluoride in amounts
greater than the maximum contaminant level of 1.4 mg/l. The groundwater in the Big Sandy basin is suitable for irrigation use
because it is not highly mineralized and the sodium concentrations generally are
smaller than those of calcium and magnesium (Davidson, 1973).
In the past, the primary use of groundwater has been for
agriculture, however, since the early 1970’s, groundwater pumped in the Big
Sandy area primarily has been used for mining. In 1980, approximately 2,000 acre-feet of groundwater were withdrawn and
roughly 95 percent of that water was transported by pipeline to the Bill
Williams basin for use in mining operations.
|
