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Salt Creek E. Coli TMDL Development
Indiana Department of Environmental ManagementWHPA determined the Total Maximum
Daily Loads (TMDLs) for the watershed
feeding Salt Creek in central Indiana.
This was performed in response to the Indiana 
Department of Environmental Management's
(IDEM) inclusion of Salt Creek on the 303(d) list
of impaired waters for violations of the E. coli
standard. Section 303(d) of the Clean Water Act
requires that TMDLs be established for each
water body in a state that does not meet the
water-quality standards for the water body's
designated use. The purpose of creating a TMDL
is to establish allowable loads of a pollutant such
that the water body will meet water-quality
standards.
Three basic steps were necessary to achieve this goal:
- Determine all sources of contamination from the watershed, both point and onpoint sources
- Determine the maximum amount of pollutant load to a water body that will maintain water-quality standards
- Allocate to each source a portion of the allowable load.
WHPA developed the TMDL for the Salt
Creek watershed by:
- compiling existing information in the watershed, including water-quality data
- analyzing the existing data
- meeting with stakeholders to communicate process and seek input
- estimating E. coli inputs from all possible sources in the watershed
- building a watershed model of the system
with the Hydrologic Simulation Program-
Fortan (HSPF) - using the calibrated model to determine the source reductions required to achieve the maximum allowable load in the creek with an appropriate Margin of Safety (MOS).
WHPA's TMDL analysis has been presented to IDEM and stakeholders in the Salt Creek basin and is being reviewed by U.S. EPA.
Project Reference:
Staci Goodwin, TMDL Program • 100 North Senate Avenue • P.O. Box 6015 • Indianapolis, IN 46206-6015
(317) 232-8603 • sgoodwin@dem.state.in.us
