PERMIT RATIONALE FOR REISSUANCE
Calhoun City POTW
Calhoun County
Calhoun City, Mississippi
Water NPDES No. MS0028134
June 2024

I.	CLASSIFICATION – NPDES Minor Municipal

II.	DESCRIPTION OF WASTEWATER – Municipal Wastewater

III.	DESCRIPTION OF WASTEWATER TREATMENT – Municipal wastewater is collected and treated by means of two conventional lagoons followed by a polishing cell thence a storage cell. The system operates as a hydrographically controlled release (HCR). Also, the discharge shall be automatically controlled between 0 and 0.32 MGD in order to maintain the river’s dissolved oxygen concentration of 5.0 mg/l. No increase in flow is proposed within the application. The facility’s discharge is listed on the Total Maximum Daily Load For Nutrients and Organic Enrichment / Low Dissolved Oxygen For the Yalobusha River, which the facility complies with via numeric limitations.

IV.	RECEIVING WATERS – Yalobusha River. The receiving water does not appear on the updated State of Mississippi 303(d) List of Impaired Waterbodies. The facility appears in a completed TMDL for Nutrients and Organic Enrichment/ Low DO. The limits proposed in this draft permit reflect the limits suggested in the TMDL. The receiving water is located in the Yazoo River drainage basin, and is classified as Fish & Wildlife. 

V.	APPLICABLE GUIDELINES – 11 MS Admin Code pt. 6, Municipal Facility Guidelines,  2024 Wasteload Allocation (WLA)

VI.	SUMMARY OF DISCHARGE LIMITATIONS – 
Parameter			Value			Basis
Flow				0.32 MGD			Design
BOD5
-	Effluent		30 mg/l (Monthly Average)		WLA
-	Mass			80.0 lbs/day 
BOD5 (Percent Removal)	65% (Minimum)			Technology
TSS
-	Effluent		90 mg/l (Monthly Average)		WLA
-	Mass			240.0 lbs/day			
TSS (Percent Removal)	65% (Minimum)			Technology
pH				6.0 – 9.0 SU			MSWQS
Ammonia Nitrogen 		14 mg/l (Monthly Average) 		WLA
Dissolved Oxygen		6.0 mg/l (Minimum)			WLA
Total Nitrogen			30.7 (Annual Avg)			TMDL
Total Phosphorus		13.9 (Annual Avg.)			TMDL 

*Permittee shall Submit a report: Due annually by the 28th of January detailing date, time, and stream stage when the discharge began; date, time, and stream stage when the discharge ceased; and the volume of wastewater released the previous year.