Geology and Geomorphology
The watershed is located within the Interior Highlands physiographic province of the United States. The Missouri portion of the watershed lies almost entirely within the Salem Plateau region, a subdivision of the larger Ozark Plateau physiographic region, with a small portion of the watershed's northwest edge in the Springfield Plateau, also a subdivision of the Ozark Plateau. The Springfield Plateau is a region of lower relief than the Salem Plateau. The Arkansas portion of the watershed also lies within the Salem Plateau and Springfield Plateau physiographic regions, and its southern-most edge is in the Boston Mountains physiographic region (Fenneman 1938).
Major drainages in the Salem Plateau are characterized by rolling uplands with local relief of 100 to 200 feet. Smaller streams are characterized by narrow valleys from 200 to 500 feet deep. The Salem Plateau has an average elevation range of 1,000 to 1,400 feet mean sea level (msl). Elevations in the eastern-most portion of the Springfield Plateau reach heights of 1,700 feet msl, and relative relief of streams reaches a maximum of 400 feet. The Boston Mountains region has local relief up to 1,000 feet in smaller stream valleys with a maximum elevation nearing 2,300 ft. msl. The Eureka Springs (Burlington) escarpment, a narrow belt of hills extending from the Osage Plain on the north to the Arkansas state line on the south, separates the Salem and Springfield plateaus (MDNR 1986a).
The uplands of the Salem Plateau are underlain by Jefferson City Dolomite and the Roubidoux Formation, and the valleys are floored by Gasconade Dolomite of Ordivician age. The Springfield Plateau is underlain by Mississippian limestones. The Boston Mountain Plateau is underlain by resistant clastic rocks of Pennsylvanian age. The Eureka Springs escarpment is the boundary between the Mississippian limestone of the Springfield Plateau and the Devonian limestone of the Salem Plateau. The geology underlying the watershed is shown in Figure Ge01.
The large dolomite mass which is present in the Ozarks has tremendous water storing capability, and the Salem Plateau is the locality for the greatest number and largest springs in Missouri, followed secondly by the Springfield Plateau. The large reservoirs in the southern part of the watershed probably cover many springs. Springs of the watershed are listed in Table Ge01 and Figure Ge02. Karst features are locally prominent in both the Salem and Springfield plateaus (MDNR 1986a). Several faults are present in the watershed, but most have only tens of feet of displacement (MDNR 1986a). The fractured limestone of the watershed allows a direct linkage from surface waters to ground waters, making aquifers underlying the watershed extremely susceptible to contamination (USGS 1996).
Soils in the Missouri portion of the watershed are of the Ozark type. The major soil association is Gasconade-Opequon-Clarksville, found in the western and central portions. A Captina-Clarksville-Doniphan association is present on the watershed's eastern edge. Other minor soil associations include Nixa-Clarksville, along the Missouri-Arkansas border, and Needleye-Viration-Wilderness, near the northwest corner (Allgood and Persinger 1979).
- Gasconade-Opequon-Clarksville soils are classified from shallow to deep, occurring on gently sloping to steep landscapes. These are loamy and clayey type, upland soils, ranging from well drained to excessively drained, formed in limestone residuum (Allgood and Persinger 1979).
- Captina-Clarksville-Doniphan soils are found on level to very steep slopes, moderately to excessively well drained. These are loamy upland soils with fragipans that are cherty throughout (Allgood and Persinger 1979).
- Nixa-Clarksville soils are found on gently sloping to very steep slopes, and are moderately well drained to somewhat excessively drained upland soils with fragipans or cherty subsoils (Allgood and Persinger 1979).
- Needleye-Viration-Wilderness soils are found on nearly level to moderately steep slopes. These are moderately well drained, loamy upland soils containing fragipans (Allgood and Persinger 1979).
- Soils in the Arkansas portion of the watershed are also Ozarkian. Major soil associations include Clarksville-Nixa-Noark, Captina-Nixa-Tonti, and Arkana-Moko in the Salem and Springfield plateaus and Linker-Mountainburg-Sidon and Enders-Nella-Mountainburg-Steprock in the Boston Mountains (USDA-SCS 1982a).
- Clarksville-Nixa-Noark soils are found on ridgetops and side slopes of the Springfield Plateau formed from cherty limestone. They range from excessively drained to moderately permeable, are found on gently sloping to very steep terrain and are very cherty, loamy upland soils (USDA-SCS 1982a).
- Captina-Nixa-Tonti soils are found on broad uplands of the Springfield Plateau, ranging from moderately well drained to very slowly permeable. They are found on nearly level to moderately sloping areas and are cherty to loamy (USDA-SCS 1982a) .
- Arkana-Moko soils are found on the ridgetops and side slopes of the Springfield and Salem plateaus, formed from cherty limestone and cherty dolomite. These soils are characterized as being moderately deep and shallow, well drained, and very slowly to moderately permeable. This soil type is found on gently sloping to very steep terrain and is very cherty and stoney (USDA-SCS 1982a).
- Linker-Mountainburg-Sidon soils are found on benches, sides, and tops of mountains formed in loamy residuum from sandstone or interbedded sandstone, siltstone, and shale. They are moderately well to well drained, nearly level to steep, loamy, gravely, or stoney soils on uplands (USDA-SCS 1982a).
- Enders-Nella-Mountainburg-Steprock soils are found on benches, sides, tops, and foot slopes of hills and mountains, formed in a thin layer of loamy colluvial material and clayey residuum from shale or interbedded shale, siltstone, and sandstone. They are well drained, deep to shallow, very slowly to moderately rapidly permeable soils, and are found on gently sloping to steep terrain (USDA-SCS 1982a).
Soil information can be obtained by contacting local Natural Resources Conservation Service (NRCS) offices throughout the watershed.
Ozark soils vary widely in character. Some soils are infertile stoney-clay type soils, while others are loess-capped and fertile. Some watershed soils are stone free, while others may have a stone content exceeding 50 percent, and some areas may have no soils covering bedrock. The majority of the watershed is dominated by stoney, cherty soils found on steep slopes with lower stone contents found in soils on more level areas. Soils in Missouri become less stoney on the western fringe of the watershed. Soils in the watershed are formed from residue high in iron, which oxidizes on exposure, giving the soil a red color. Soils formed in the residuum from cherty limestone or dolomite, range from deep to shallow and contain a high percentage of chert in most places. Soils formed in a thin mantle of loess are found on the ridges and have fragipans, which restrict root penetration. Soils formed in loamy, sandy, and cherty alluvium are found in narrow bottomland areas, and are the most fertile soils in the watershed (Allgood and Persinger 1979).
Soils in the watershed are generally acidic and of moderate to low fertility. Productivity of watershed soils varies widely, with forest and grassland being the dominant land cover (USDA-SCS 1975). A typical watershed landscape consists of broad forested areas on moderately steep to very steep slopes and small pastures and cultivated fields on smoother ridgetops and in level valley bottoms. Tall fescue is the main grass used for pastures. Native, tall and midtall grasses are found in glade and savannah areas. They are less common than before European settlement (Allgood and Persinger 1979). The moisture holding capacity of these soils is limited, adding to the general unsuitability for crop production. (USDA-SCS 1975).
Soil erosion in the Missouri portion of the watershed is minimal relative to other areas in the state. Sheet and rill erosion on tilled land is 18-24 tons per acre, but totals across the watershed should be very low considering the small portion of the area in cultivation. Sheet and rill erosion for permanent pasture is 5-9 tons per acre. Sheet and rill erosion for non-grazed forest is 0.25-0.50 tons per acre. The gully erosion problems are considered slight, and problems associated with erosion are localized (0-100 tons per sq. mi.). The amount of sediment that reaches streams is estimated to be between 0.8-0.9 tons per acre annually (Anderson 1980).
The White River is a sixth order stream where it enters Missouri in southeastern Barry County. The White becomes a seventh order stream at its confluence with the Kings River and an eighth order river shortly afterwards at the confluence with the James River. Today these order changes have little to do with size or flow increases within Missouri since both reaches are now impounded by Table Rock Dam. The White River remains an eighth order river where it enters the Mississippi River.
The entire White River basin comprises an area of 27,765 square miles. The portion of the White River covered by this document has an area of 5,184 square miles, making up 18.7 percent of the entire White River basin. The Missouri portion of the watershed includes 2,281 square miles (44%), and the Arkansas portion of the watershed includes 2,903 square miles (56%).
Stream gradient information has been calculated for all streams third order and larger in the Missouri portion of the watershed. This information is available from MDC's Southwest Regional Office in Springfield, MO.