Geology and Geomorphology
The Spring River Tributaries Watershed lies within the Salem Plateau Subdivision of the Ozark Plateau. The Salem Plateau is a heavily dissected plateau with upland elevations of between 1,000 and 1,400 feet (MDNR 1986). Local relief on the uplands is between 100 to 200 feet. In areas of deeply intrenched valleys, local relief ranges between 200 to 500 feet. Elevations within the Spring River Tributaries Watershed range between 1,200 feet above sea level in the uplands to less than 500 feet above sea level in the lower portions of the watershed within Missouri, specifically the Warm Fork of the Spring River at the state line.
The surface of the Spring River Tributaries Watershed occurs almost entirely within Jefferson City Dolomite. The only exception to this is a two mile section of the Warm Fork occurring within the sandstone and cherty dolomite of the Roubidoux Formation which underlies the Jefferson City Formation (Figure Ge01)(MSDIS 1998 and MDNR 1994). Due to the nature of the surface geology of the watershed as well as climatic conditions, there are many karst features present here including sink holes, losing streams, and springs (MDNR 1986 and MDNR 1994). The two most prominent karst features within the watershed are the Grand Gulf (Missouri), and Mammoth Spring (Arkansas). The Grand Gulf, part of Grand Gulf State Park, is a large sinkhole into which Bussel Branch, a third order stream, drains. Successful dye traces have shown that much of this flow resurfaces at Mammoth Spring in Arkansas which has an average discharge of 300 cfs making it the 2nd largest spring in the Ozarks (MDNR 1994). This is despite the fact that streams of the watershed do not incise the Gasconade Dolomite Formation which is the top formation of the three formations in which most of the largest springs in Missouri occur (MDNR 1994; Vineyard and Feder 1974).
The Spring River Tributaries Watershed occurs within the Ozark Soils Region. Allgood and Persinger (1979) describe the Ozark Soils Region as "cherty limestone ridges that break sharply to steep side slopes of narrow valleys. Loess occurs in a thin mantle or is absent. 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. Some of the soils formed in a thin mantle of loess are on the ridges and have fragipans, which restrict root penetration. Soil mostly formed under forest vegetation with native, mid-tall and tall grasses common in open or glade area."
The following is a list of soil associations found in the Spring River Tributaries Watershed in Missouri: Lebanon-Hobson-Clarksville, Captina-Macedonia-Doniphan-Poynor, Captina-Clarksville-Doniphan, Wilderness-Clarksville-Coulstone, Hartville-Ashton-Cedargap-Nolin (alluvial), (Allgood and Persinger 1979).
Stream Mileage, Order and Permanency, Springs
Using United States Geological Survey (USGS) 7.5 minute topographic maps, a total of 77 third order and larger streams were identified within the Spring River Tributaries Watershed within Missouri (Table Ge01, Figures Ge02, and Ge03). These streams account for approximately 392 stream miles. Of the 77 third order and larger tributaries within the watershed, 54 are third order, 16 are fourth order, 5 are fifth order, and 2 are sixth order. Table Ge02 shows length of stream per order for fourth order and larger streams within the watershed.
Drainage areas have been determined from digital raster graphic (drg) versions of USGS 1:100,000 and 1;24,000 scale topographic maps. The drainage area of the Spring River Tributaries Watershed in Missouri is 307,200 acres or 480 square miles. The watershed has been divided into six subwatersheds (not to be confused with the 14 digit hydrologic units or the drainage sections which are used in this document for display purposes) based on drainage areas accounting for > 5% of the total drainage area of the Spring River Tributaries Watershed (Figure Ge04). The Warm Fork Subwatershed is the largest subwatershed within the Spring River Tributaries Watershed. It encompasses a total of 265 square miles and includes most of the major populated places within the watershed including the cities of West Plains and Thayer, Missouri.
Using United States Geological Survey (USGS) 7.5 minute topographical maps, the extent of permanent and intermittent flow has been determined for third order and larger streams within the Spring River Tributaries Watershed. (Table Ge03, Figure Ge02, and Ge03). Of the 392 miles of third order and larger streams, 99.8 miles (25%) have permanent flow. The Warm Fork of the Spring River has the longest length of permanent stream at 22.6 miles. Spring Creek below Arrowhead lake has the highest percentage of permanent stream versus total length at 100 percent.
In an effort to further delineate stream flow as well as the cold water resource within the watershed, stream crossing temperature checks were performed during the summers of 1996, 1997, and 1998 by Missouri Department of Conservation Ozark Region Fisheries personnel.
Results from this study generally corresponded with the USGS 7.5 minute topographical maps with a few exceptions. One site on Howell Creek below Big Gressy Creek went completely dry in 1997. However, a site above and below had permanent pools for all years. Another notable exception is the fact that permanent water appears to exist in some headwater streams within the watershed which were previously shown to be intermittent on USGS maps. Two examples of this are the North Fork of Howell Creek and Galloway Creek (Legler, personal communication). Flows from both streams are eventually lost to the groundwater system. These represent somewhat unique features given their headwater characteristics in addition to the fact that they exist in an area highly influenced by karst topography. In order to fully appreciate the significance of these small reaches of permanent headwater streams further study will be required. Figure Ge05 shows the remaining flow data including other additional sites with permanent flow. It is important to note that sites which were found to be dry in a single year were not checked in proceeding years. Additionally, sites found to be dry the first year are not included in Figure Ge05.
The karst nature of the Spring River Tributaries Watershed is evident in the amount of losing streams within the watershed. There are 78.5 miles of stream within the watershed which are designated as losing streams by MDNR (1996)(Table Ge04). This is important to note when considering potential point and nonpoint pollution effects not only within the immediate watershed, but also on the groundwater system and thus well systems as well as other watersheds. Dye traces conducted within the watershed and adjoining watersheds by various state and federal agencies as well as one private individual have shown that much of the water lost to the ground water network in the watershed resurfaces at Mammoth Spring at the head of the Spring River in Arkansas (MDNR 1995, 1996). Two dye traces which had injection points outside the watershed also were recovered at Mammoth Spring (Figure Ge06). This illustrates the point that surface ground water system boundaries do not always coincide with surface watershed and subwatershed boundaries.
There are 17 named springs within the Spring River Tributaries Watershed as determined by data obtained from United States Geological Survey (USGS) Geographic Names Information System (GIS) Database (Table Ge05 and Figure Ge07). The only springs within the watershed listed by Vineyard and Feder (1974) are Lost Spring and Mammoth Spring in Arkansas. Lost Spring has a discharge of .02 cfs (13,000 gallons/day), while Mammoth Spring, the second largest spring in the Ozarks has a discharge of 240 cfs (155,000,000 gallons/day). Little information regarding flow rates, chemical characteristics, or recharge area appears to be available relating to the remaining springs. However, some of these springs within the watershed are believed to have significant flow. The Warm Fork receives enough spring influence below Warm Fork Spring to be designated for Cold-Water Sport Fishery by the Missouri Department of Natural Resources (MDNR 1996). Data from long term temperature recorders (thermographs) indicate significant spring influence in other stream reaches as well (Figure Hc02 and Hc03). Given the influence on aquatic habitat demonstrated by some springs as well as the karst nature of this watershed, these springs represent a significant characteristic of the subwatershed and should be studied in more depth.
Gradient Plots were digitized from 7.5 minute USGS topographical maps for all fourth order and larger streams within the Spring River Tributaries Watershed in Missouri (Table Ge06). Composite gradient graphs were generated for fifth order and larger streams within the watershed. The Warm Fork of the Spring River/Howell Creek (6th order) have the lowest overall stream gradient at approximately 11 feet/mile; while stream EPW070 (4th order) has the highest overall stream gradient at approximately 79 feet/mile.