PERMIT RATIONALE FOR REISSUANCE
Pachuta POTW
Clarke County
Pachuta, Mississippi
Water - NPDES Draft Permit No. MS0035700
November 2023

I.	CLASSIFICATION – Municipal Minor NPDES
II.	DESCRIPTION OF WASTEWATER – Municipal Minor Domestic
III.	DESCRIPTION OF WASTEWATER TREATMENT – Domestic wastewater is collected and treated biologically by means of a lagoon system.  No increase in flow is proposed within the application. The current design capacity of the facility is 0.054 MGD.
IV.	RECEIVING WATERS – Pachuta Creek. Pachuta Creek does not appear on the updated The State of Mississippi List of impaired Waterbodies. The discharge, however, appears on a Fecal Coliform TMDL, which the facility complies with via disinfection. The 7Q10 of the receiving stream is 1.90 cfs; this along with the facility’s design flow of 0.054 MGD (0.083 cfs) results in an Instream Waste Concentration (IWC) of 4.2%.  This waterbody is in the Pascagoula drainage basin.  Pachuta Creek is classified as Fish and Wildlife.  
V.	APPLICABLE GUIDELINES – 11 MS Admin Code pt. 6, 2023 Wasteload Allocation (WLA), Municipal Guidelines
VI.	SUMMARY AND BASIS OF DISCHARGE LIMITATIONS - The following limitations have been developed through empirical modeling:    
Parameter	Current Permit Value		Basis	
Flow	0.054 MGD		Design	
BOD5	30 mg/l		WLA	
TSS	90 mg/l		Technology	
e. Coli	126 Col./100ml		WLA	
pH	6.0 to 9.0		MS WQS	
Chlorine	0.26 mg/l		WLA	
Dissolved Oxygen, minimum	6 mg/l		Admin Code
	
BOD5, % removal	65%		Technology	
TSS, % removal	65%		Admin Code