Background and Focus of Report
The State of Kansas, under the Clean Water Act of the United States, lists the designated uses of stream segments for contact and non-contact recreation, aquatic life support, domestic water supply, food procurement, etc. The surface-water quality standards of Kansas that are applicable to a given water depend upon which designated uses apply to that water. Water-quality monitoring assesses the concentration of substances present in the water relative to the applicable standards. If the assessment indicates consistent non-achievement of the standards, the water is deemed impaired relative to its designated uses.
The Kansas Department of Health and Environment (KDHE) is establishing Total Maximum Daily Loads (TMDL) in Kansas on all stream segments with designated uses to provide a quantitative basis for the water-quality assessment. A TMDL is the maximum amount of a substance that a surface-water body can receive without violating water-quality standards. The TMDL process also attributes responsibility for pollutant loads among point and nonpoint sources. There are several steps in the process of developing TMDL's. Two of these include estimation of the type, location and magnitude of pollutant sources contributing loads to the water body, and estimation of the linked relationship between those pollutant sources and their relative impact on the ambient water quality of the water body, including the anticipated response in water-quality condition upon load modifications arising from the contributing sources.
Chloride has been selected as one of the substances to be considered as possible pollutants in the TMDL process. The Water Quality Standards of Kansas (KDHE, 1998) describe and list standards for surface-water quality. The numeric criterion for chloride concentration for domestic water supply under public health use is 250 mg/L. The criteria for chloride content for aquatic life use are 860 mg/L for acute toxicity and 352 mg/L for chronic toxicity.
There are many areas of naturally saline ground waters in Kansas that are high in chloride concentration. These saline waters naturally discharge into some stream segments. Anthropogenic contributions to stream chloride concentration derive from many nonpoint and point sources, both from past and current activities and waste discharges. The KGS has developed methods for geochemically differentiating among selected saltwater sources, for example, between natural saltwater from the dissolution of subsurface rock salt and formation brine associated with oil and gas production. These and other studies and procedures allow the KGS to determine the natural state of the water quality and identify significant human sources contributing to the chloride and sulfate load of waters. The KDHE requested the KGS apply this knowledge concerning natural sources and the procedures for differentiating salinity sources to assist in the process of developing the TMDL's for chloride.
The goal for this report is to ascertain the sources, relative contributions of dissolved chloride, and changes in salt concentration along stream segments in the Lower Arkansas River Basin cited as impaired by chloride under Section 303(d) of the Clean Water Act. The focus is on the Arkansas River in the Gar-Peace Subbasin and the Cow Creek Subbasin where stream segments are listed by the KDHE as impaired by chloride with a high implementation priority. The project objectives for this report are to
- Quantify the sources, location, magnitude and variability of chloride concentrations in impaired stream segments of the Gar-Peace and Cow Creek subbasins of the Lower Arkansas River Basin.
- Distinguish natural intrusion of chloride in the impaired segments from conditions aggravated by anthropogenic activities.
The outcome of the project is a synoptic analysis assessing the sources of chloride load contributions and evaluating the linkage between those sources and resulting stream water quality.
Description of Impaired Streams
The Gar-Peace Subbasin of the Lower Arkansas River Basin includes the Arkansas River from its confluence with Rattlesnake Creek in southwest Rice County through Reno County to the confluence with the Little Arkansas River in Wichita in Sedgwick County. The main stem segments 1, 3, 4 and 5 and tributary 7 (Salt Creek) are listed by the KDHE as impaired by chloride with a high implementation priority. Salt Creek enters the Arkansas River to the southwest of Hutchinson in Reno County. Another tributary of significance entering the Arkansas River in the Gar-Peace Subbasin is Peace Creek, which flows from eastern Stafford County through northwest Reno County to join the Arkansas River at the south-central edge of Rice County. A few other minor tributaries enter the river in the subbasin, including Gar Creek, which drains a small part of east-central Reno County and enters the Arkansas River in the northwest comer of Sedgwick County. There are 4 fixed sites where the KDHE collects samples from the Arkansas River for monitoring of surface-water quality: at the 4th Avenue bridge to the west of Hutchinson (site number 523), to the southeast of Hutchinson at the bridge north of Yoder (524), at the bridge north of Haven (283) in east-central Reno County, and at the bridge northeast of Maize (536). There are two rotational sites where the KDHE collects samples from tributaries: Peace Creek (658) near the north edge of Reno County a few miles upstream of the confluence with the Arkansas River, and Salt Creek (659) about two miles upstream of the confluence with the Arkansas River and approximately 0.5 mile south of Arkansas River sampling site 523.
Cow Creek Subbasin
Cow Creek is a major tributary that flows into the Arkansas River along the Gar-Peace Subbasin in the Hutchinson area in Reno County. Cow Creek and its tributaries are classified as a separate subbasin. The main stem segments of Cow Creek (1, 3, 5, 6) start at the confluence with the Arkansas River in the Hutchinson area and extend upstream through Rice County to northeast Barton County. The drainage basin includes the watershed of Cheyenne Bottoms. Streamflow from Cow Creek splits into three different flow paths in the Hutchinson area: the Cow Creek diversion canal on the west side of Hutchinson that flows into the Arkansas River to the southwest of Hutchinson, the Harsha canal that enters the Arkansas River in southwest Hutchinson, and the Cow Creek channel that flows through Hutchinson and enters the Arkansas River to the southeast of Hutchinson and north-northeast of Yoder. During sampling of Cow Creek in the Hutchinson area in July 2002, the most western diversion canal had substantially more flow than either the Harsha canal or the channel to the southeast of Hutchinson.
The tributary segments in the Cow Creek Subbasin include, in upstream confluence order. Little Cow Creek (2), Spring Creek (20), Lost Creek (17), Plum Creek (4), Calf Creek (16), and Little Cheyenne Creek (7). The outlet canal from the Cheyenne Bottoms Waterfowl Refuge drains into the headwaters of Little Cheyenne Creek in southeast Barton County. Chloride impairment is currently listed by the KDHE as a high implementation priority for the main stem segments 1, 3, 5, and 6 of Cow Creek. There are 4 fixed sites where the KDHE collects samples in the Cow Creek Subbasin for monitoring of surface-water quality: Little Cow Creek (656) south of Lyons, Cow Creek south of Lyons (657), Cow Creek at Willowbrook (522) to the northwest of Hutchinson, and Cow Creek about 0.5 mile upstream of the confluence with the Arkansas River (287).