Onondaga Lake

• Discharges affecting the Onondaga Lake in New York, last 12 months3939 affecting this stretch: 39 reported in New York, none arriving from upstreamDecember 2025 to November 2026Verified reports where available, else notices; revisions and duplicates counted once. Arriving discharges are estimated from modeled downstream reaches.
• Days with a discharge affecting the Onondaga Lake in New York, last 12 months57Reported on the Onondaga Lake in New York: 57 · Arriving from outfalls upstream, estimated: 0December 2025 to November 2026A day counts once however many discharges were under way on it. Verified reports where available, else notices; revisions and duplicates counted once.
• Hours with a discharge or advisory status on the Onondaga Lake in New York, last 12 months663Reported on the Onondaga Lake in New York: 663 · Arriving from outfalls upstream, estimated: 0December 2025 to November 2026Red hours by the map's rules: each discharge to its reported end plus the state's post-discharge period; overlapping hours count once.
• 2026 season with a discharge or advisory status on the Onondaga Lake in New York1.5%May to October 2026Share of May 1 to October 31 hours with red status by the map's rules, of the hours a source covered.
• Records behind the last-90-days strip for the Onondaga Lake in New York2Reported on the Onondaga Lake in New York: 2 · Arriving from outfalls upstream, estimated: 0last 90 daysEvery distinct record the strip lists for its red, yellow and unresolved hours, notices and unresolved reports included; counted as the strip counts them.

Combined sewer overflow (CSO): sewage mixed with rainwater spills from a shared sewer system. Sanitary sewer overflow (SSO): sewage spills from a sewer meant to carry sewage separately from rainwater. Treatment bypass: wastewater skips one or more treatment steps. Blended discharge: wastewater that skipped some treatment is mixed with treated wastewater. Outfall: a pipe or outlet where wastewater enters a water body.