Final Approved TMDL
Skillet Fork Watershed
Final Report Page 9 December 2006
11. Public Participation: Numerous opportunities were provided for local
watershed institutions and the general public to be involved. The Agency
and its consultant met with local municipalities and agencies in summer
2004 to gather and share information and initiate the TMDL process. A
number of phone calls were made to identify and acquire data and
information (listed in the Stage 1 Report). As quarterly progress reports
were produced, the Agency posted them to their website. In March 2005, a
public meeting was conducted in Wayne City, Illinois to present the Stage
1 findings. A second public meeting was held in Wayne City, Illinois in
July 2006 to present the Stage 3 (TMDL) results. One additional public
meeting will be held at a later date to present the implementation plan.
Stephen A. Forbes Lake (IL_RCD)
1. Identification of Waterbody, Pollutant of Concern, Pollutant Sources,
and Priority Ranking: Stephen A. Forbes Lake, HUC 0512011502. The
pollutant of concern addressed in this report is total phosphorus.
Potential sources contributing to the listing of Stephen A. Forbes Lake
include: Agricultural runoff, sediment phosphorus release during seasonal
hypolimnetic anoxia and failing septic systems. Stephen A. Forbes Lake is
reported on the 2006 303(d) list as being in category 5, meaning available
data and/or information indicate that at least one designated use is not
being supported or is threatened, and a TMDL is needed (IEPA, 2006).
Because this watershed has a public water supply use impaired, it was
ranked as high priority on the 303(d) list for TMDL development.
2. Description of Applicable Water Quality Standards and Numeric
Water Quality Target: The water quality standard for total phosphorus
to protect aquatic life and aesthetic quality uses in Illinois lakes is 0.05
mg-P/l. For the Stephen A. Forbes Lake phosphorus TMDL, the target is
set at the water quality criterion for total phosphorus of 0.05 mg-P/l.
3. Loading Capacity – Linking Water Quality and Pollutant Sources:
The water quality model BATHTUB was applied to determine that the
maximum phosphorus load that will maintain compliance with the
phosphorus standard is 108.8 kg/month (3.63 kg-P/day) between March
and August, with the total load not to exceed 653 kg over this period.
4. Load Allocations (LA): The Load Allocation designed to achieve
compliance with the above TMDL is 95.6 kg/month (3.19 kg-P/day) for
the period March-August.
5. Wasteload Allocations (WLA): There are two point source dischargers in
the Stephen A. Forbes Lake watershed. The WLA for these facilities was
set at estimated existing loading conditions (2.32 kg-P/month or 0.08 kg-
P/day). This allocation assumes that these facilities discharge continuously
at their permitted design average flow. It is known, however that these
facilities rarely discharge, and so this allocation is conservative.
