Record Display for the EPA National Library Catalog


OLS Field Name OLS Field Data
Main Title TMDL for Turbidity for White Oak Creek, AR.
CORP Author FTN Associates, Little Rock, AR.; Environmental Protection Agency, Dallas, TX. Region VI.
Year Published 2006
Report Number EPA/CN-68-C-02-108
Stock Number PB2013-100896
Additional Subjects Water quality standards ; Water pollution ; Turbidity ; Streams ; Arkansas ; Clean water act ; State regulations ; Watersheds ; Total Maximum Daily Load(TMDL) ; White Oak Creek(Arkansas)
Library Call Number Additional Info Location Last
NTIS  PB2013-100896 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. 07/24/2013
Collation 58p
Section 303(d) of the Federal Clean Water Act requires states to identify waterbodies that are not meeting water quality standards and to develop total maximum daily pollutant loads for those waterbodies. A total maximum daily load (TMDL) is the amount of a pollutant that a waterbody can assimilate without exceeding the established water quality standards for that pollutant. Through a TMDL, pollutant loads can be allocated to point sources and nonpoint sources discharging to the waterbody. The study area for this report is the White Oak Creek watershed in central Arkansas. The study area is part of the Arkansas Department of Environmental Quality (ADEQ) Planning Segment 3F and is located within the Arkansas River Valley ecoregion. Land use in the study area is about 50% pasture, 34% forest, and 15% urban. White Oak Creek is included on the draft 2004 Arkansas 303(d) list as not supporting the aquatic life use due to exceedances of numeric criteria for turbidity. The applicable numeric criteria for turbidity for this reach are 21 NTU (primary value) and 40 NTU (storm-flow value). ADEQ historical water quality data were available for one location on White Oak Creek. These data were analyzed for long term trends, seasonal patterns, relationships between concentration and stream flow, and relationships between turbidity and total suspended solids (TSS). These analyses showed that the highest values of turbidity and TSS occurred between May and November and during low flow conditions. Also, higher turbidity levels tended to correspond with higher TSS values. This TMDL was expressed using TSS as a surrogate for turbidity because turbidity cannot be expressed as a mass load. Two regressions between TSS and turbidity were developed using the ADEQ data. Using the base flow regression equation with the turbidity criterion values, the target TSS concentration of 12 mg/L (corresponding to the primary turbidity criterion of 21 NTU) was identified. Using the storm-flow regression equation with the turbidity criterion values, the target TSS concentration of 14 mg/L (corresponding to the storm-flow turbidity criterion of 40 NTU) was identified.