PERMIT RATIONALE FOR REISSUANCE
Noxapater POTW, South
Winston County
Noxapater, Mississippi
Water NPDES No. MS0021628
March 2023

I.	CLASSIFICATION –Municipal NPDES Minor 

II.	DESCRIPTION OF WASTEWATER – Domestic / Municipal Wastewater

III.	DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is collected and treated by means of a lagoon, followed artificial wetlands.  No increase in flow is proposed within the application.  

IV.	RECEIVING WATERS – Gum Branch.  The receiving water is located within the Pearl River Basin and is classified as Fish and Wildlife.  At the point of discharge Gum Branch does not appear on the current State of Mississippi 303(d) list of impaired waterbodies, but Noxapater Creek does appear as evaluated waterbody for aquatic life support due to organic enrichment/ low do, nutrients, sediment/ siltation, and pesticides. The discharge is also listed in a Completed TMDL due to Pathogens.  Requirements for a Mercury Minimization Plan, as set forth in the mercury TMDL, has been completed in the previous permit. At the point of discharge the 7Q10 for the receiving stream is 0.014 cfs.  The instream wastewater concentration at the point of discharge can be determined by the following calculation:

IWC = {(Qw)/(Qw + Qr)}*100

	Where, Qw = Design flow of the wastewater treatment facility, 0.06 MGD or 0.093 cfs
		 Qr = Receiving stream 7Q10, 0.0 cfs.

IWC = {(0.093 cfs)/(0.093 cfs + 0.0 cfs)}*100 = 86.90 %

V.	APPLICABLE GUIDELINES – 11 MS Admin Code pt. 6, Mississippi Water Quality Standards (MSWQS), Municipal Facility Guidelines

VI.	SUMMARY OF LIMITATIONS –
Parameter				Flow				Basis
Flow					0.06 MGD			Design
BOD5					10 mg/l				WLA	
BOD (Percent Removal)		85% Minimum			Technology
Minimum DO				6 mg/l				WLA
TSS					30 mg/l				Technology
TSS (Percent Removal)			85% Minimum			Technology
NH3-N	(Phase I)			2.0 mg/l			WLA
NH3-N	(Phase II)			1.37 mg/l			WLA
E Coli		 			126 Col./100 ml 		MSWQS	
Chlorine, Total Residual 		0.013 mg/l			MSWQS & IWC
pH					6.0 – 9.0 SU			MSWQS
Total Nitrogen				5.76 lb/day			WLA
Total Phosphorus			2.60 lb/day			WLA