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The Natural Resources of Yavapai County
Compiled by: Jeff Schalau
Yavapai County is one Arizona's original territorial counties formed in 1864. The County encompasses 8,122 square miles and 5 square miles of water. For comparison, the area is about the same size as the State of New Jersey. Thirty-eight percent of the land is administered by the U.S. Forest Service, 9% by the U. S. Bureau of Land Management, 27% by the State of Arizona, 26% is held privately by individuals or corporations, and less than 0.5% is held in trust as Indian Reservation. There are three Indian reservations located in the county -- the Yavapai-Prescott Indian Reservation, the Clarkdale, and the Camp Verde Indian Reservation.
The first territorial government in Arizona was established 20 miles north of present day Prescott in 1863 and moved to the site of Prescott in 1864. Prescott was the center of gold mining activity and one of the most productive areas of the Southwest. The principal industries today include tourism and recreation, ranching, manufacturing, and mining.
The population of Yavapai County increased rapidly in the last 38 years -- from 31,000 inhabitants in 1962 to 62,300 in 1978 to 107,714 in 1990 to 167,517 in 2000. The population increased 56 percent from 1990 to 2000, making Yavapai the second fastest growing county in Arizona. Sixty-six percent of the population lives in the western part of the county. The leading city is Prescott (the county seat), with a population of 33,938. Other cities in the county include Prescott Valley (23,535 residents), Cottonwood/Verde Village (19,789 residents), Camp Verde (9,451 residents), Chino Valley (7,835 residents), Sedona (7,229 residents in the Yavapai County portion), and Jerome (329)(data from 2000 Census).
Topography and Soils
The terrain varies in elevation of 1,900 feet to just under 8,000 on its mountain peaks. The county lies in the center of a 100-mile strip of Ponderosa pine forests which crosses the state from the northwest corner to the eastern border. Other vegetation types include: mixed conifer, pinyon-juniper, chaparral, desert grassland, and upper Sonoran desert. The Prescott National Forest, as well as portions of the Kaibab, Coconoino, and Tonto National Forests, are in the county.
Big Chino Valley (elevation 4,300 - 4,600 ft) consists of gently rolling to flat topography in the valley floor. The average soil depth is 4 - 6 ft. The soil is sandy loam to clay loam with a pH of 7.0 - 7.8.
Chino Valley (elevation 4,400 - 4,700 ft) has rolling land and steep runs in most areas. The average soil depth is 2 ft. The soil is underlain by gray-white, semi-impervious layer of caliche resulting in perched water table in portions of the valley when irrigated. The topsoil varies from sandy loam to clay loam with an average pH of 7.0 -7.8.
The Verde Valley (Cottonwood-Camp Verde-Sedona area, elevation 3,000 - 3,300 ft) has fairly steep slopes in some areas. Soils in the upper and middle Verde and part of the lower Verde Valley are sandy to sandy loams; the lower Verde has some clay loams. Soils tend to be heavily leached. Soil depth is approximately 3 - 5 ft underlain by coarse gravels
Skull Valley (elevation 4,200 - 4,400 ft) has a fairly level valley floor. It is a narrow valley running north and south with slightly shorter daylight hours than at Chino Valley. Soils are valley fill soils, often rather sandy.
The climate varies from Sonoran Desert at the lower elevations to mid-Canada at the higher elevations. The temperature variation from daytime high to night-time low throughout the year is about 35 degrees.
Prescott has a semi-arid climate with abundant precipitation only from early July through mid-September. During the rest of the year, rainfall is generally deficient. Temperatures from June through September average between 65 and 70 degrees F. Only in about two of every five summers are readings above 100 degrees recorded. Average winter temperatures at Prescott are above freezing in all months. Minima below zero degrees occur on the average on one or two mornings in every other winter. The average growing season is 140 days.
Climate Data for Prescott
* Percent probability that a minimum temperature below the threshold will occur on or before the given date.
Cottonwood has a semi-desert climate, with an average annual rainfall of just over 12 inches. The most arid conditions occur in the spring, although completely dry months are uncommon. The summers at Cottonwood are warm, but comfortable, with temperatures frequently climbing above 100 degrees. The evenings are pleasantly cool, when readings in the upper fifties prevail. During the winter, early morning temperatures typically fall into the upper twenties in December and January. Daytime maxima normally hover around sixty degrees. The average number of growing days is 194.
Climate Data for Cottonwood
* Percent probability that a minimum temperature below the threshold will occur on or before the given date.
Climate data is available for several other Yavapai County locations at the Western Regional Climate Center web site: www.wrcc.dri.edu. Specific Arizona station data can be accessed at www.wrcc.dri.edu/summary/Climsmaz.html.
John H. Hatch discovered artesian water in little Chino Valley in 1930. This led to the development of Little Chino Valley as an important sector of the Yavapai County farm economy. In 1990, Yavapai County had approximately 7,500 acres under irrigation. This included 5,700 acres in commercial farms and l,800 acres in small operations in Camp Verde, Cottonwood, and Chino Valley.
Small grains and pasture make up most of the irrigated acreage in the county. In 1990, there were 700 acres of wheat harvested (average yield 3,400 lbs. per acre), 2,000 acres of alfalfa harvested (average yield of 4.0 tons per acre), and 1,500 acres of other hay harvested (average yield 3.0 tons per acre). Cash receipts for crops peaked in 1979-1980. Today, the acreage planted in small grains, hay, and pasture are too small to accurately quantify. In addition, there are a small number of fruit and vegetable producers: most of the crops produced are sold directly to the public through farmer's markets and roadside stands.
According to the 1997 Census of Agriculture, there are 453 farms in the county. While the majority of the farms provide supplemental or part-time income, 37 agricultural operations sold products valued at more than $100,000. Sixty-one percent of the farms (275) sold agricultural products valued at less than $10,000 and 31% (141) sold products valued at $l0,000 to $99,999.
Several commercial honey producers live in the county. In 2000, the average yield per colony in Arizona was 59 lbs. and overal production was 2,360,000 pounds. Prices for the 1990 honey crop averaged 73 cents per pound.
Yavapai County ranching and livestock production began as early as the 1860's. Some of the earliest ranching families in Yavapai County included the Fain's who originally settled in the Camp Verde area in the 1860's from Kentucky, the Jackson's who registered the third homestead in Arizona near Kirkland in the 1860's, the Rees' family also settling during the 1860's, the Ritter's who came from Texas and California before coming to Arizona in 1868, the Carter's who came from Kansas to settle in the Walnut Grove area in 1873, and the Perkins' who drove cattle from Texas to Arizona in 1900 (the above historical information was supplied by Danny Freeman, Prescott Historian).
Yavapai County ranchers have experienced many challenges through the years including drought, low cattle prices, and, more recently, managing for endangered species. Yavapai County's principal source of agricultural income is from the approximately 67,000 head of cattle and calves. In 2000, cash receipts for livestock and livestock products were $79,028,000. According to a study done by J.L. Maynard, Economic Characteristics of the Livestock Producers of Yavapai County, Arizona, Yavapai College, May 1996, an average Yavapai County ranch contributes $44,091 in direct expenditures to the local economy.
Yavapai County Agricultural Production (1986-2000)
The above data was provided by the Arizona Agricultural Statistics Service. Their web site can be accessed at http://www.nass.usda.gov/az/
Rangelands are a kind of land that includes grasslands, shrub lands, woodlands, open forests and some deserts. Rangelands in Yavapai County are characterized by their diversity in vegetation and soil types and their complex land ownership patterns. In addition to providing forage for grazing animals, they also provide wildlife habitat, open space, and sources of water and recreational opportunities.
A majority of the public lands in Yavapai County are leased for livestock grazing. Grazing fee formulas are determined by the matching agency (US Forest Service, Bureau of Land Management, State Land Department). For more information about Arizona ranching, see Questions and Answers about Ranching in Arizona and the other resources at the University of Arizona AgNIC web site at ag.arizona.edu/agnic/.
The major rangeland vegetation types found in Yavapai County are listed below:
Ponderosa Pine - Dense stands of Ponderosa pine are found above 5,000 feet elevation where precipitation is greater than 16 inches per year. Other important trees include Gambel oak, Arizona walnut, aspen, Douglas fir, and white fir. Grasses may include blue grama, western wheatgrass, Arizona and sheep fescue, moutain and screwleaf muhly, junegrass, muttongrass, and dryland sedges. These areas are primarily used for summer range.
One hundred years of aggressive fire suppression has allowed dense, overstocked stands of Ponderosa pine to develop. These areas are becoming the focus of fuels reduction activities (mechanical, prescibed fire, and small diameter timber sales). These treatments result in increased grasses, herbaceous plants, and shrubs and improve suitability for grazing, wildlife, and recreation.
Pinyon-juniper - Extensive areas in Yavapai County support stands of juniper and pinyon pine. Typical stands can be found north of Chino Valley, Ashfork, south of Seligman, and in much of the country between Sedona and Stoneman Lake.
Pinyon-juniper ranges often produce an under story of blue grama intermixed with side-oats grama, western wheatgrass, and tobosa. Winterfat, cliffrose, and silktassel may be locally abundant. As grass stands become thinner, weeds such as annual goldeneye and clubflower fill in the openings. Snakeweed and threadleaf groundsel may become common. In areas where the pinyon-juniper canopy has closed, grasses and herbaceous plants become rare to nonexistent. These closed stands often exhibit evidence of sheet erosion, and in extreme cases, rills and gullies are present.
Grassland - Short-grass range lies largely at elevations between 4,000 and 5,000 feet. Typical areas occur in the Verde Valley, north of Prescott, in Chino and Lonesome Valleys, and along Interstate 40 between Ash Fork and Seligman.
In climax plant communities, blue grama, tobosa, black grama, hairy grama, and side-oats grama predominate. Ring muhly and red three-awn may be present but make up only a small part of the total vegetation.
On fair to poor condition ranges, blue grama may still be abundant; there is little side-oats grama. Ring muhly and red three-awn are usually plentiful. Weeds, including Russian thistle, tumble-mustard, and sunflower are frequently common. Snakeweed occurs occasionally and on shallow soils on the better-condition ranges; it may be more abundant on deteriorated ranges.
Chaparral - Chaparral is a shrub dominated plant community occurring most often between the elevations of 3,000 and 5,500 feet. An extensive stand of chaparral lies in the area between Cherry and Dewey and extends south past Humboldt and Mayer. Other typical areas are Iron Springs Road (northwest of Prescott), Wilhoit, and Camp Wood.
Scrub oak often dominates our chaparral plant communities. Other shrubs include manzanita, lemonade berry, mountain mahogany, Apache plume, catclaw, cliffrose, ceanothus, and silktassel. Some of these shrubs are palatable to livestock and wildlife year-round. Therefore, chaparral is often used as winter range.
Grasses may be present but are less abundant than in other vegetation types. The most common are blue grama, side-oats grama, black grama and wolftail. On the poorer sites, red three-awn and annual bromes may be common.
Desert Grassland - This is the most arid of the range vegetation in Yavapai County. Desert grassland occurs extensively in the Verde Valley and the southwest corner of the county in the Date Creek and Hassayampa River drainages and west of the Weaver and Date Creek Mountains.
Tobosa is the dominant grass; other grasses are black grama, hairy grama, and curly mesquite. Filaree is abundant in the spring during years when winter precipitation is favorable. Two low-growing shrubs, shrubby buckwheat and bur sage, are locally abundant. Larger shrubs such as whitethorn, yucca, crucifiction thorn, and creosote bush are common in some areas. Mesquite and palo verde trees may also be present.
Desert shrub - The desert shrub type lies at the lowest elevations occurring in Yavapai County. The common shrubs which occur are palo verde, catclaw, whitethorn, creosote, bur sage and various cacti. Bush muhly is probably the most palatable grass. Tobosa grass occurs in low places where runoff waters collect. Annuals such as filaree and Indian wheat may also be abundant in the spring during years when winter precipitation is favorable.
The State of Arizona is divided into three water provinces: the Plateau Uplands in the north, the Central Highlands, and the Basin and Range Lowlands in the south. Yavapai County lies in the Central Highlands and is characterized by high precipitation, rapid run-off, and low evaporation. The direction of movement of the surface water is toward the Salt River Valley. Before the water reaches the valley, it is impounded in the mountains by Bartlett, Roosevelt, and Coolidge Dams. There is little or no ground-water underflow in these tributary valleys because the streams flow over bedrock for many miles.
Historically, there were two major areas of groundwater development in Yavapai County: the Verde Valley and Chino Valley.
Verde Valley - The Verde Valley is a northwest trending valley extending from Perkinsville to the junction of Fossil Creek and Verde River. Verde River, Oak Creek, West Clear Creek, and Beaver Creek flow in the valley. The Verde River and Oak Creek were used for irrigating that area; twenty-seven different irrigation ditches exist in the Verde Valley. The towns of Clarkdale, Cottonwood, Camp Verde and Sedona lie within the area.
In the Clarkdale-Cottonwood-Camp Verde area of the Verde Valley, the principal source of ground water is the Verde formation of Pliocene or Pleistocene age. Water sources include the Verde River and other streams, shallow wells near the river, and deeper drilled wells. In some parts of the valley there is enough artesian pressure to cause wells to flow. In the northern part of the valley, livestock get water from wells as deep as 800 feet.
In the Sedona area of the Verde Valley, the principal source of ground water is the Supai formation of Pennsylvania and Permian age. Before 1949 enough water for the Sedona area was available from surface flow in Oak Creek and shallow wells next to the creek. During the late 1950's, the increase in population required the development of more convenient and dependable domestic water supplies.
Chino Valley - Del Rio Springs was a landmark known to pioneers as a permanent and plentiful source of water. It is located just beyond the northern limit of the artesian area. In 1863 Whipple Barracks was located at this site and then moved to Prescott. In 1904 the City of Prescott built a pumping station at Del Rio Springs and pumped water 21 miles into the city through an 8-inch pipe line. The operation was discontinued in 1926.
In 1926 the first well to tap the artesian aquifer, four feet in diameter and 150 feet to water, was drilled at the Mormon Church. An irrigation well was put down by a group of local farmers in Chino Valley in 1930. Before the discovery of flowing artesian water in Little Chino Valley, irrigation in the valley was limited to lands in the Chino Valley Land and Irrigation Company. From 1915 to 1926, farmers in the area got a surface water supply from the Lake Watson Reservoir on Granite Creek about 5 miles below Prescott.
By 1937, there were fourteen irrigation wells in the area. In 1940, the depth to static water level of the well at the Mormon Church was measured at 158 feet. By 1974 it had dropped to 228 feet. The decrease in static water level may be explained, in part, by an increase in the number of irrigated acres, from 1,004 acres in 1939 to 2,758 acres in 197l. However, in 1948, the City of Prescott bought and retired agricultural land from production in Little Chino Valley to obtain a municipal supply of water. In 2000, the citizens of Prescott voted to purchase Watson Lake from the Chino Valley Irrigation District.
The Arizona Department of Water Resources (ADWR) has identified several groundwater basins within Yavapai County. Most of the inhabited areas with the county fall within one of these basins: the Verde River Basin, the Upper Hassyampa Basin, the Agua Fria Basin, and the Bill Williams Basin. The remaining area is within the Prescott Active Management Area (AMA).
Geographic areas designated as having critically impacted groundwater supplies were designated as Active Management Areas (AMAs). The Prescott Active Management Area covers 485 square miles in central Yavapai County and is the smallest and northernmost of the AMAs. The Prescott AMA is bounded by the Bradshaw Mountains to the south, Granite Mountain and Sullivan Buttes to the west, and the Black Hills to the northeast.
Prescott Active Management Area - The Arizona Groundwater Management Code (Code) was passed in 1980 to help address the issue of water supplies within Arizona. The Code has three primary goals. The first is to control the severe overdraft currently occurring in many parts of the state. The second goal is to provide a means to allocate the state's limited groundwater resources to most effectively meet the changing needs of the state. The Code's third goal is to augment Arizona's groundwater through water supply development. To accomplish these goals, the Code set up a comprehensive management framework and established the Arizona Department of Water Resources (ADWR) to administer the Code's provisions.
The Prescott AMA has a statutory goal of achieving safe-yield by 2025. Safe-yield means that the amount of groundwater pumped from the aquifer on an average annual basis must not exceed the amount that is naturally or artificially recharged. The safe-yield goal is a basin-wide balance. This means that water level declines in one portion of the AMA can be offset by recharging water in another part of the AMA.
All new wells are permitted through Yavapai County Development Services. Yavapai County works in cooperation with the ADWR during the permitting process. ADWR has some data on groundwater conditions in areas where wells are commonly drilled (water.az.gov). Well drillers may also provide anecdotal information pertaining to an area's historic groundwater supplies. Some areas have little or no significant groundwater supplies and residents in these areas must haul potable water to their homes.
Water quality is excellent in most of the county. Water pH is usually between 6.5 and 8.5. Total dissolved solids (TDS) are usually at or below 500 ppm. Water in drilled wells is sometimes high in sodium salts, particularly near the Salt Mine south of Camp Verde. Camp Verde also has areas where wells contain high levels of naturally occurring arsenic.
Between 1996 and 2001, Cooperative Extension has assisted over 1,000 private well owners in testing their water for nitrate contamination. Several areas have shown elevated nitrate levels. These include: Dewey, Chino Valley, northwest Prescott, Clarkdale, Cottonwood, Bridgeport, Camp Verde, and Cornville. The source of nitrates are not known. In other areas of the United States, nitrate contamination has been linked to irrigated agriculture, concentrated livestock facilities, large turf areas, septic systems, and naturally occurring deposits.
Noxious weeds are plants specified by law or regulation to be particularly undesirable, destructive and difficult to control. Yavapai County has several known noxious weed populations. Russian knapweed (Acroptilon repens) may be the most widespread noxious weed in the county with populations in Chino Valley, Cottonwood, Peeples Valley, Prescott, and the Upper Verde River. Yellow Starthistle (Centaurea solstitialis) is pictured to the right and occurs on the south side of Camp Verde. Malta Starthistle (Centaurea melitensis) occurs in Cottonwood and Cordes Junction. Mediterranean sage (Salvia aethopis) occurs in the Peeples Valley area. Dalmatian toadflax (Linaria dalmatica) and Scotch Thistle (Onopordum acanthium) occur throughout Prescott, Chino Valley, Prescott Valley, the Bradshaw Mountains, Seligman, and other areas. Isolated populations of spotted knapweed (Centaurea maculosa) and quackgrass (Elytrigia repens) occur in Prescott. Hoary Cress (Cardaria draba) jointed goatgrass (Aeglilops cylindrica) occur in Prescott, Chino Valley, and the Camp Wood area. Sweet resinbush (Euryops subcarnosus) occurs south of Cottonwood.
Two Weed Management Areas (WMAs) are located in Yavapai County: these are the West Yavapai WMA and Verde WMA. The West Yavapai WMA is contained within the boundaries of the Triangle and Chino Winds Natural Resource Conservation District (NRCD) and the Verde WMA is within the Verde NRCD. These informal groups meet monthly and coordinate weed management activites and educational efforts that teach community members about the threat of noxious weeds. The contact person for the West Yavapai WMA is Jeff Schalau (928.445.6590). The contact person for the Verde WMA is Clare Hydock (928.567.4121).
Natural Resource Management Agencies
These agencies and contacts have knowledge and expertise related to natural resources within their disciplines and jurisdictions.