PERMIT RATIONALE FOR REISSUANCE
Sunnyhill Water Association
Pike County
Fernwood, Mississippi
Water NPDES No. MS0044199
December 2025

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 an aerated lagoon followed by disinfection.  No increase in flow is proposed within the application.  

IV.	RECEIVING WATERS – Little Tangipahoa River.  The receiving water is located within the South Independent Streams Basin, and is classified as Fish and Wildlife.  The Little Tangipahoa River does not appear on the updated State of Mississippi 303(d) list impaired waterbodies. The discharge is listed in a completed TMDL for Organic Enrichment/ Low DO and Ammonia Nitrogen on the Little Tangipahoa River. The wasteload allocated (WLA) limits are derived from the TMDL. At the point of discharge the 7Q10 for the receiving stream is 2.0 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, 0.04 MGD or 0.06 cfs
		 Qr = Receiving stream 7Q10, 2.0 cfs.

IWC = {(0.06 cfs)/(0.06 cfs + 2.0 cfs)}*100 = 3.0%

V.	APPLICABLE GUIDELINES – 11 Mississippi Admin Code pt. 6, Municipal Facility Guidelines (Technology), State of Mississippi Water Quality Criteria (MSWQS), Wasteload Allocation (WLA)

VI.	SUMMARY OF LIMITATIONS –
Parameter			Value					Basis
Flow				0.04 MGD				Design
BOD5				45 mg/l 				WLA
BOD (Percent Removal)	65% Minimum				Technology
Phase I NH3-N			Report mg/l				Previous Permit
Phase II NH3-N			2.0 mg/l	WLA
Minimum DO			6.0 mg/l				WLA
TSS				90 mg/l 				Technology
TSS (Percent Removal)		65% Minimum				Technology
E. Coli				126 Col./100 ml				WLA
Chlorine, Total Residual	0.037 mg/l 				WLA
pH				6.0 – 9.0 SU				WLA
Total Nitrogen 			Report (mg/l)				WLA
Total Phosphorus		Report (mg/l)				WLA

VII.	CHANGES TO PREVIOUS PERMIT

The 2025 Waste Load Allocation established a more stringent limit for Ammonia Nitrogen based on Ammonia Toxicity. The proposed draft reflects that change.

The following conditions were added to the proposed draft permit:

1.	“The permittee shall achieve compliance with the effluent limitations specified for discharge in accordance with the following schedule:
“Upon issuance of this permit, the permittee shall achieve compliance with the effluent limitations specified for the parameters without a phase designation and for the parameters noted as Phase I; Phase II limitations shall not apply at this time.”

“Beginning upon completion and start-up of improvements needed to comply with Phase II limitations or three (3) years after the issuance of the permit, whichever comes first, the permittee shall achieve compliance with the effluent limitations specified for the parameters without a phase designation and for the parameters noted as Phase II; Phase I limitations shall no longer apply at this time. Phase II limitations shall apply as soon as the treatment system has demonstrated compliance with the Phase II limitations, but no longer than three (3) years after the issuance of the permit.”

“The permittee shall notify our office orally at least 24 hours prior to start-up and in writing no later than 48 hours after start-up.”

2.	“The Permittee shall Submit engineering report: Due once within 6 months (180 days) after effective date. Said report shall outline the improvement activities needed to upgrade the wastewater treatment facility to comply with the site's Phase II limitations and shall include a proposed schedule for those improvement activities.”

3.	“The Permittee shall Submit progress report: Due annually - every 1 year after effective date. Said report shall update the Permittee's progress in addressing needed upgrades to the wastewater treatment facility in order to meet the site's Phase II limitations. Said report should also include an updated schedule for completing these activities.”