Sewage in the Water

When a sewer in New York spills untreated sewage, the operator has to tell the public within four hours. Those reports are the NY-Alert texts. This map plots every one, over the 911 outfalls where combined sewers are allowed to overflow when it rains.

–discharging now, by their own reported times

–discharges reported in the last 24 hours

–gallons reported in the last 24 hours

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Combined sewer Sanitary sewer Plant or other

Discharging now Ended in the last 24 hours Ended in the last 3 days Older Permitted combined sewer outfall Outfall on a system that reported in this window Buffalo Sewer forecast: high or moderate overflow risk

Bigger circles mean more gallons.

CSO outfalls Buffalo live risk

How often

Discharges

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Where this comes from

The 2013 Sewage Pollution Right to Know law makes every sewage treatment plant and sewer system report untreated and partially treated discharges to DEC within two hours and to the public within four. They file through NY-Alert, which texts subscribers and feeds the most recent notices to DEC’s website. This page reads that list every ten minutes and keeps a copy of each notice, so its own history grows from the day it went live.

The 1 year and All windows add DEC’s SPRTK spreadsheet, every notice since January 2021, about 35,000 of them. DEC warns that it may be incomplete from July 2021 on, and it has holes: December 2025 is almost empty, December 2021 and January 2022 are thin, and nothing exists between the spreadsheet’s last notice (September 1, 2026) and the first one this page saved. Before mid-2023 the spreadsheet gives only the day a discharge started, not the time. Notices from the same address that started the same day count as one discharge.

Each notice is free text typed by the operator. Volumes, start times and durations are their estimates, and DEC does not check them. A rate like “10 gallons per minute” is multiplied by the reported duration to get a total. Many combined sewer overflows are reported after they have already stopped, and wet-weather CSOs do not have to file an ending report, so “discharging now” means the reported start time plus the reported duration has not passed yet.

Points are placed by geocoding the reported discharge address (U.S. Census geocoder, then OpenStreetMap). A few addresses only resolve to the town, and those points are approximate.

Outfall locations are DEC’s Combined Sewer Overflows dataset on data.ny.gov. Its overflows per year are from each system’s own monitoring or model, mostly as of 2015. The Buffalo layer is Buffalo Sewer Authority’s own live overflow-risk forecast for its 52 outfalls, which is a prediction, not a measurement. New York City reports its CSOs through DEP’s Waterbody Advisory instead, so the city’s outfalls rarely light up here.

A map by Ryan Sajdak.

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