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Hydrology of the Detrital Valley Basin

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).

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).

Click to view Table 4.3-5

Click to view Table 4.3-5 Groundwater Conditions in the Detrital Valley Basin

Click to view Figure 4.2-6

Click to view Figure 4.3-6 Detrital Valley Basin

Groundwater Conditions

Click to view Figure 4.3-8

Click for Figure 4.3-8 Detrital Valley Basin Well Yields

Click to view Figure 4.0-5

Figure 4.0-5 Upper Colorado River USGS Watersheds

Surface Water Hydrology

The U.S. Geological Survey (USGS) divides and subdivides the United States into successively smaller hydrologic units based on hydrologic features.  These units are classified into four levels. From largest to smallest these are: regions, subregions, accounting units and cataloging units.  A hydrologic unit code (HUC) consisting of two digits for each level in the system is used to identify any hydrologic area (Seaber et al., 1987). A 6-digit unit code corresponds to accounting units, which are used by the USGS for designing and managing the National Water Data Network.  (See Figure 4.0-5)

Lower Colorado- Lees Ferry to Lake Mead Watershed

The Lower Colorado River-Lees Ferry to Lake Mead watershed is located in the Western Plateau Planning Area and in the northern portion of the Upper Colorado River Planning Area.  Included within the Upper Colorado River Planning Area portion of the watershed are the Hualapai Valley and Meadview basins, almost all of the Detrital Valley Basin, all but the far eastern portion of the Peach Springs Basin and the northernmost part of the Big Sandy Basin.

The major north-flowing tributaries to the Colorado River in the Upper Colorado River Planning Area portion of the watershed are Hualapai Wash and Detrital Wash.  These washes are ephemeral and contribute little to the flow of the Colorado River.  The other major wash is Truxton Wash in the Peach Springs and Hualapai Valley basins, which flows north to Red Lake, a dry lake.  The Colorado River is the only perennial water supply in the part of the  watershed in the planning area.  There is only one intermittent stream, a portion of Truxton Wash, located in Peach Springs Basin (AZGF, 1997 & 1993).

Lake Mead, created by Hoover Dam, has affected groundwater conditions in adjacent basins in the watershed.  There is outflow from the lake into the surrounding aquifers.  Lake Mead extends from Hoover Dam in the Lake Mohave Basin, along the planning area boundary to Peach Springs Basin.  Maximum storage in Lake Mead is 29.7 maf.  Of this, approximately 2.38 maf is “dead storage” - the reservoir capacity from which stored water cannot be evacuated by gravity.  The average storage during the period from 1996 to 2005 was 20.3 maf. 

Hualapai Valley Red Lake

Red (Dry) Lake, Hualapai Valley Basin.  The Colorado River is the only perennial water supply in the portion of the Lower Colorado - Lees Ferry to Lake Mead Watershed in this planning Area.

Twenty-four major springs (springs with a measured discharge rate of 10 gpm or greater at any time) are found in the watershed, primarily located in the Peach Springs and Meadview basins. Generally, springs with the greatest discharge are located in the Hualapai Plateau in the Peach Springs Basin, where discharges of 1,730 gpm at Spencer Spring and 1,233 gpm at Meriwhitica Spring have been measured.  With the exception of a number of springs measured in the early 1990s, particularly in the Peach Springs Basin, most of the spring measurements were recorded over 30 years ago and may not reflect current conditions.  For example, recent discharge measurements taken at two “major” springs in the Peach Springs Basin were less than 10 gpm. (See Springs tables in each basin section.)

There is only one streamgage in the watershed at Spencer Creek near Peach Springs.  Median flows at this gage are about 1,500 AFA.




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