Based on historic stream assessments, the Indiana Department of Environmental Management (IDEM) has placed the H.D. Wood Ditch (Mud Creek) on the 303(d) list of impaired waters for elevated chlorides. Elevated chlorides can inhibit growth and development of aquatic biota, but do not pose any human health hazard. IDEM has established Water Quality Based Effluent Limits (WQBELs) for chlorides in the effluent of the Angola WWTP that the utility cannot meet. Conventional wastewater treatment does not remove chlorides. WWTP effluent chloride will generally equal influent chloride plus any internal chloride addition. Since Angola is in the Great Lakes river basin, effluent limitations include daily maximum and maximum monthly average concentration limits and loading limits. There are only two general methods to meet the WQBEL’s: (1) limit chlorides discharged to the treatment plant (source reduction); (2) use tertiary treatment to remove chlorides post WWTP treatment.

The Wastewater Utility has applied for, and anticipates receiving, a variance from the WQBEL in its permit. If approved, the variance will provide interim chloride limits that are not as stringent as the WQBEL, but will require certain efforts to be taken to reduce effluent chloride from the treatment plant.