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Northwest Airport Management LP

Airports, Flying Fields, & Services, Harris County, Texas. NPDES permit TX0138479, in force until Oct 31, 2029. Last 12 months: no values over a limit, 8 required values missing, 4 of 11 reports late. Source: EPA ECHO, Oct 22, 2026.

Reports due: About 20 days after each period: form A monthly (8 values)
Last report on file: August 2026
Oct 2024 – Sep 2025: 0 values over a limit, 0 required values missing, 0 of 12 reports late

Limits in force (8)

Parameter	Statistic	Limit	Months
Oxygen demand, chem. [high level] [COD]	daily maximum	report only (mg/L)	all year
pH	minimum	≥ 6 SU	all year
pH	maximum	≤ 9 SU	all year
Solids, total suspended	daily maximum	≤ 100 mg/L	all year
Oil & Grease	daily maximum	≤ 15 mg/L	all year
Zinc, total [as Zn]	daily maximum	report only (mg/L)	all year
Flow, in conduit or thru treatment plant	daily average	report only (MGD)	all year
Flow, in conduit or thru treatment plant	daily maximum	report only (MGD)	all year

New limits from Nov 1, 2027

Parameter	New limit	New or tighter	Median, last 12 months	× new limit
Zinc, total [as Zn], daily average	0.175 mg/L	new	—	—
Zinc, total [as Zn], daily maximum	0.372 mg/L	new	—	—

How strict are these limits?

Oil & Grease, daily maximum 15 mg/L — stricter than 21% of 265 other minor industrial and other permits in Texas; 78% have the same limit

Cited limits by parameter: Texas's rules and the federal ones.

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On EPA ECHO: Facility report · DMR history

Your permit document is the final word. As JSON: /api/v1/permits/TX0138479 · MCP: https://passage-data.com/mcp