PORTLAND STP
NPDES ID: TN0021865
S — SNC: Compliance schedule violation
The facility missed a deadline in its compliance schedule by more than 90 days.
This quarter: 3 effluent violations.
Violations
May 31, 2026
SSO, Wet Weather
Limit violation
Discharged 0.13160001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
SSO, Dry Weather
Limit violation
Discharged 0.09870001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
April 30, 2026
SSO, Dry Weather
Limit violation
Discharged 0.0329 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
March 31, 2026
SSO, Dry Weather
Limit violation
Discharged 0.09870001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, total [as N]
222% over limit
Discharged 23.5 mg/L against a permitted limit of 7.3 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, total [as N]
96% over limit
Discharged 102.90817914 kg/d against a permitted limit of 52.52779956 kg/d (MO AVG)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 0.0658 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, total [as N]
147% over limit
Discharged 36.1 mg/L against a permitted limit of 14.6 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
February 28, 2026
SSO, Dry Weather
Limit violation
Discharged 0.19740001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
17% over limit
Discharged 2.58 mg/L against a permitted limit of 2.2 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
72% over limit
Discharged 2.58 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
8% over limit
Discharged 17.21113986 kg/d against a permitted limit of 15.88999987 kg/d (MO AVG)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 0.19740001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
64% over limit
Discharged 4.92 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
January 31, 2026
SSO, Wet Weather
Limit violation
Discharged 0.19740001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
15% over limit
Discharged 3.45 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
December 31, 2025
SSO, Dry Weather
Limit violation
Discharged 0.0329 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 0.36190002 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
November 30, 2025
SSO, Dry Weather
Limit violation
Discharged 0.0329 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 0.0658 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
September 30, 2025
SSO, Dry Weather
Limit violation
Discharged 0.0658 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
July 31, 2025
Nitrogen, total [as N]
3% over limit
Discharged 11.3 mg/L against a permitted limit of 10.95 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 0.09870001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
SSO, Dry Weather
Limit violation
Discharged 0.0329 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, total [as N]
33% over limit
Discharged 9.71 mg/L against a permitted limit of 7.3 mg/L (MO AVG)
DMR, Limited - Numeric Violation
June 30, 2025
SSO, Dry Weather
Limit violation
Discharged 0.0329 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 1.08570006 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
May 31, 2025
SSO, Wet Weather
Limit violation
Discharged 0.19740001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
April 30, 2025
SSO, Dry Weather
Limit violation
Discharged 0.0329 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 1.44760008 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
March 31, 2025
SSO, Dry Weather
Limit violation
Discharged 0.0658 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 0.75670004 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
February 28, 2025
SSO, Dry Weather
Limit violation
Discharged 0.19740001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 1.7766001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
January 31, 2025
Phosphorus, total [as P]
4% over limit
Discharged 33.60507972 kg/d against a permitted limit of 32.37019973 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, total [as N]
116% over limit
Discharged 113.40465905 kg/d against a permitted limit of 52.52779956 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, total [as N]
5% over limit
Discharged 7.66 mg/L against a permitted limit of 7.3 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Solids, suspended percent removal
28% over limit
Discharged 23.33 % against a permitted limit of 40 % (DAILY MN)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 1.01990006 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Solids, suspended percent removal
43% over limit
Discharged 78.55 % against a permitted limit of 85 % (MO AV MN)
DMR, Limited - Numeric Violation
Solids, settleable
11% over limit
Discharged 0.00111 mg/L against a permitted limit of 0.001 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, total [as N]
44% over limit
Discharged 113.40465905 kg/d against a permitted limit of 78.76899934 kg/d (WKLY AVG)
DMR, Limited - Numeric Violation
SSO, Dry Weather
Limit violation
Discharged 0.0658 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
December 31, 2024
SSO, Wet Weather
Limit violation
Discharged 1.34890008 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, total [as N]
0% over limit
Discharged 52.66399956 kg/d against a permitted limit of 52.52779956 kg/d (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
13% over limit
Discharged 2.48 mg/L against a permitted limit of 2.2 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Solids, suspended percent removal
35% over limit
Discharged 79.7 % against a permitted limit of 85 % (MO AV MN)
DMR, Limited - Numeric Violation
Solids, suspended percent removal
67% over limit
Discharged 0 % against a permitted limit of 40 % (DAILY MN)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
36% over limit
Discharged 4.07 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
November 30, 2024
Solids, suspended percent removal
28% over limit
Discharged 23.3 % against a permitted limit of 40 % (DAILY MN)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
233% over limit
Discharged 10 mg/L against a permitted limit of 3 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Solids, total suspended
47% over limit
Discharged 66 mg/L against a permitted limit of 45 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
SSO, Wet Weather
Limit violation
Discharged 0.36190002 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
88% over limit
Discharged 4.13 mg/L against a permitted limit of 2.2 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
SSO, Dry Weather
Limit violation
Discharged 0.0658 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Chlorine, total residual
18% over limit
Discharged 0.013 mg/L against a permitted limit of 0.011 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
33% over limit
Discharged 1.99 mg/L against a permitted limit of 1.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
October 31, 2024
Nitrogen, ammonia total [as N]
508% over limit
Discharged 8.51 mg/L against a permitted limit of 1.4 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
SSO, Dry Weather
Limit violation
Discharged 0.0658 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
13% over limit
Discharged 0.791 mg/L against a permitted limit of 0.7 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
217% over limit
Discharged 3.17 mg/L against a permitted limit of 1 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
105% over limit
Discharged 23.2175598 kg/d against a permitted limit of 11.3499999 kg/d (WKLY AVG)
DMR, Limited - Numeric Violation
September 30, 2024
SSO, Wet Weather
Limit violation
Discharged 0.59220003 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
August 31, 2024
Chlorine, total residual
100% over limit
Discharged 0.04 mg/L against a permitted limit of 0.02 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
32% over limit
Discharged 0.66 mg/L against a permitted limit of 0.5 mg/L (MO AVG)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
504% over limit
Discharged 6.04 mg/L against a permitted limit of 1 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
60% over limit
Discharged 12.90721989 kg/d against a permitted limit of 8.08119993 kg/d (WKLY AVG)
DMR, Limited - Numeric Violation
SSO, Dry Weather
Limit violation
Discharged 0.09870001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
205% over limit
Discharged 2.29 mg/L against a permitted limit of 0.75 mg/L (WKLY AVG)
DMR, Limited - Numeric Violation
July 31, 2024
Oxygen, dissolved [DO]
34% over limit
Discharged 3.98 mg/L against a permitted limit of 6 mg/L (INST MIN)
DMR, Limited - Numeric Violation
Solids, settleable
300% over limit
Discharged 0.004 mg/L against a permitted limit of 0.001 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
Nitrogen, ammonia total [as N]
117% over limit
Discharged 2.17 mg/L against a permitted limit of 1 mg/L (DAILY MX)
DMR, Limited - Numeric Violation
SSO, Dry Weather
Limit violation
Discharged 0.13160001 occur/d against a permitted limit of 0 occur/d (MO TOTAL)
DMR, Limited - Numeric Violation
First flagged
April 14, 2026 (3 months ago)
Last confirmed
July 13, 2026 (23 days ago)