NIWOT SANITATION DISTRICT WWTF

NPDES ID: COG591186

X — SNC: Effluent violation (non-monthly average limit)

The facility discharged more of a pollutant than its permit allows, measured over a period other than a monthly average.

This quarter: 2 effluent violations.

Mentions

Nitrogen spikes twice in four months at Niwot plant

The Niwot Sanitation District wastewater plant exceeded its permitted nitrogen discharge limit for the second time this year three days ago, releasing inorganic nitrogen at 45 percent above the allowed threshold. The first violation, earlier this year, ran 123 percent over limit. The pattern is now unmistakable: two exceedances in a single calendar year at a single facility. The timing could hardly be worse. Boulder Creek is running at a fraction of its normal summer flow right now — too shallow to dilute anything that enters it — and the creek is already formally listed as impaired under the Clean Water Act. Excess nitrogen in warm, slow water fuels algal blooms and starves the water column of oxygen, conditions that stress every aquatic insect, fish, and invertebrate that depends on a functioning creek. Yet across the entire permit district, no penalties have been assessed. What this repetition signals is a watershed already struggling to recover facing cumulative stress from the same source, year after year. The cleanup plans that were supposed to restore Boulder Creek to health have been in development for years.

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Violations

June 30, 2026

Static Renewal 7 Day Chronic Ceriodaphnia dubia

40% over limit

Discharged 60 toxic against a permitted limit of 100 toxic (MN VALUE)

DMR, Limited - Numeric Violation

April 30, 2026

Nitrogen, inorganic total

45% over limit

Discharged 14.5 mg/L against a permitted limit of 10 mg/L (DAILY MX)

DMR, Limited - Numeric Violation

March 31, 2026

Nitrogen, inorganic total

65% over limit

Discharged 16.5 mg/L against a permitted limit of 10 mg/L (DAILY MX)

DMR, Limited - Numeric Violation

February 28, 2026

Nitrogen, inorganic total

122% over limit

Discharged 22.2 mg/L against a permitted limit of 10 mg/L (DAILY MX)

DMR, Limited - Numeric Violation

January 31, 2026

Nitrogen, inorganic total

123% over limit

Discharged 22.3 mg/L against a permitted limit of 10 mg/L (DAILY MX)

DMR, Limited - Numeric Violation

First flagged

April 14, 2026 (4 months ago)

Last confirmed

September 1, 2026 (4 days ago)