Liberte Environmental Associates

NPDES Permits Potentially Affecting Water Quality


Final NPDES Wastewater Permits - Issued by Oregon Department of Environmental Quality

This list consists of permit documents* (see end) made available by Oregon DEQ and is not all inclusive. All documents are PDF except where indicated.

Tryon Creek Sewage Treatment Plant (STP): Final NPDES Wastewater Permit Related Documents

Tryon Creek STP - Final Permit*

Tryon Creek STP - Final Fact Sheet

Existing TMDL for the Willamette River - Finalized in September 2006.

Permitted Mixing Zone Size for Toxicity:
Waterbody: Willamette River at about River Mile (RM) 20.3.
Acute Mixing Zone:
20 feet downstream from the outfall multi-port diffuser.
Acute Mixing Zone Surface Area: MZ width not given in the permit or fact sheet and SA is not yet determinable.
Chronic Mixing Zone: 200 feet downstream.
Chronic Mixing Zone Surface Area: MZ width not given in the permit or fact sheet and SA is not yet determinable.
Chronic Mixing Zone Volume: MZ width is not given and the MZ volume is not yet determinable. However, DEQ does provide a Willamette River MZ depth of 50 feet in the fact sheet (see page 5, Section - Outfalls).


*LEA Disclaimer for compiled, unlocked and OCR documents: From time to time LEA will post on this website scanned documents, and additional documents otherwise limited in accessibility. Accordingly, LEA may use document unlocking and optical character recognition (OCR) capabilities to provide accessible, tagged text documents for use by people with visual impairments, and also provide searchable documents. The unlocking and OCR processes are not faultless, and hence LEA cannot guarantee document perfection. However, taking these caveats into account, document accessibility is greatly increased. LEA also posts the original document where necessary, as obtained by LEA, such that users may compare any potential imperfections in the unlocked and OCR documents.