DirtyWaterWatch Public waters. Public record.

Washington / Waters /

Lake Washington

Lake in Washington, near Beaux Arts Village, Bellevue, Kirkland, Lake Forest Park, Mercer Island, Renton, Seattle and Yarrow Point

Current status

Discharge possible: heavy rain, no report received

Radar shows that recent rain at a combined sewer system's outlets has reached the amount set for that system, and its operator has not reported a discharge. It reads "discharge likely" where the amount is the one at which that system has discharged before, or a rain trigger its state publishes, and "discharge possible" where only this site's default of 0.1 inch applies. This is an estimate, not a report. This status since . Why this status, and its source

Map sources: water outlines and launches from OpenBoatLaunch and OpenStreetMap contributors (Open Database License); wastewater outlets from EPA and state records; downstream estimates by DirtyWaterWatch using U.S. Geological Survey maps and flow data. Base map: OpenFreeMap and OpenMapTiles.

Solid dots mark combined sewer outfalls. Grey dots are closed outfalls. A yellow ring with a dashed edge means discharge likely or possible: heavy rain, no report received. Square boat markers mark boat launches listed by OpenBoatLaunch.

Rain expected: 0.17 in forecast in the next 24 hours (NWS forecast issued Nov 5, 2026, 1:26 PM EST); discharges here have begun at 0.1 in. A forecast, not a report.

Check King County Wastewater Treatment Division (West Point, South, Brightwater, Vashon and Carnation plants and King County's CSOs)'s notices · Bookmark this water page and check it before each trip · Report a missing notice or error

About this status

Discharge possible: heavy rain, no report received: heavy rain at a sewer operator's outlets reached this site's default amount, and no report received; shown for 48 hours after the rain (site rule). 3.1 in of rain fell in the 24 hours to Nov 6, 2026, 12:00 AM EST at King County Wastewater Treatment Division (West Point, South, Brightwater, Vashon and Carnation plants and King County's CSOs)'s outfalls (NOAA radar estimate).

Source: NOAA National Weather Service, MRMS radar-only rainfall estimate, valid Nov 6, 2026, 12:00 AM EST, retrieved 2026-11-06 06:09 UTC; threshold: site default; rule: How it works, discharge likely or possible. · Updated

The last 90 days

Last 90 days, hour by hour. Red: discharge or advisory reported. Amber: caution. Hatched amber: end not confirmed. Plum: algal bloom advisory. Red or amber with a light line inside: beach advisory or caution. Dotted: monthly report (days with discharge, dates not given). Grey: no current status on the water outline. Purple hatching: a status resting on a source that could not be checked on schedule.
  • Discharge likely or possible: heavy rain, no report received: to the latest update
    Radar estimate, no report received: heavy rain at the outlets of King County Wastewater Treatment Division, Seattle Public Utilities
  • Caution: to
    1 report: Seattle Public Utilities 1
    Show records

    The records are also in the report table on this page.

  • Discharge or advisory reported: to
    1 report: Seattle Public Utilities 1
    Show records

    The records are also in the report table on this page.

Source: DirtyWaterWatch calculations using the reports named above and the published status rules. Updated 2026-11-06 06:13 UTC.

Reported discharges over time

  • Discharges affecting Lake Washington in Washington, last 12 months11 affecting this lake: 1 reported on Lake Washington; 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 Lake Washington in Washington, last 12 months2Reported on Lake Washington in Washington: 2 · Arriving from outfalls upstream, estimated: 0 (counted apart; together they need not equal the total)December 2025 to November 2026A day counts once however many discharges were under way on it.
  • Hours with a discharge or advisory status on Lake Washington in Washington, last 12 months7Reported on Lake Washington in Washington: 7 · 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 Lake Washington in Washington0.2%May to October 2026; incomplete source coverageShare 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 Lake Washington in Washington3Reported on Lake Washington in Washington: 1 · Arriving from outfalls upstream, estimated: 0 · Other records (rain-likely and similar): 2last 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.

This record covers Lake Washington within Washington; the same lake in another state is a separate record.

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.

Reported discharges per month

1 reported discharge, January 2022 to November 2026.

  • Combined sewer overflow
  • Sanitary sewer overflow
  • Treatment bypass, blended or other
  • No tracked source for this period
  • Incomplete source coverage
Limited records

No tracked source covers January 2022 to April 2022.

Source: wa-ecology-sewage-spills. Records cover June 15, 2026 to November 6, 2026.

Show table

Hours with a discharge or advisory status per month

Hours when this water had a discharge or advisory status under DirtyWaterWatch rules.

  • Discharge or advisory reported
  • No tracked source for this period
  • Incomplete source coverage
Limited records

No tracked source covers January 2022 to April 2022.

Source: wa-ecology-sewage-spills. Records cover June 15, 2026 to November 6, 2026.

Show table

Days with a reported discharge per month

A day counts when any counted discharge was under way on it, from its start to its reported end in Eastern Time; a report with no end counts its start day.

  • No tracked source for this period
  • Incomplete source coverage
Limited records

No tracked source covers January 2022 to April 2022.

Source: wa-ecology-sewage-spills. Records cover June 15, 2026 to November 6, 2026.

Show table

Reported volume per year

Gallons (axis: K thousand, M million), summed from the 1 report that gave a volume as a number.

  • Incomplete source coverage
Limited records

Source: wa-ecology-sewage-spills. Records cover June 15, 2026 to November 6, 2026.

Show table

Hours with a discharge or advisory status per year

Hours with a discharge or advisory status each year under DirtyWaterWatch rules; 2026 to date.

  • Discharge or advisory reported
  • Incomplete source coverage
Limited records

Source: wa-ecology-sewage-spills. Records cover June 15, 2026 to November 6, 2026.

Show table

Share of the May to October season with a discharge or advisory status

Share of the hours from May 1 to October 31 with a discharge or advisory status under DirtyWaterWatch rules.

  • Discharge or advisory reported
  • Season with incomplete source coverage

Seasons with incomplete source coverage: 2026. The share is of the hours a source covered.

Source: wa-ecology-sewage-spills. Records cover June 15, 2026 to November 6, 2026.

Show table

Reported discharges by calendar month, all years

Every counted discharge report, by the calendar month it began.

Months are summed over every year a tracked source covers; the table gives the number of years behind each month.

Source: wa-ecology-sewage-spills. Records cover June 15, 2026 to November 6, 2026.

Show table

Reported discharges by wastewater outlet

Wastewater outlets with the most tracked discharge records: 1 of 1, all years. Counts depend on reporting coverage and do not measure legal compliance or harm.

Source: wa-ecology-sewage-spills. Records cover June 15, 2026 to November 6, 2026.

Show table
How these charts are counted

We count each discharge once. Where a source publishes notices and confirmed reports, we use confirmed reports for an operator's month when available; otherwise we use notices. We combine revisions and exclude duplicate state reports copied by the U.S. Environmental Protection Agency (EPA). Monthly and yearly totals appear separately. Status hours follow this site's rules. Shaded gaps mean missing coverage, not zero discharges.

  • U.S. Environmental Protection Agency sewer overflow records: records from May 3, 2022 to the latest update (limited records)
  • wa-ecology-sewage-spills: records from June 15, 2026 to the latest update
  • wa-kc-cso-status-csv: records from November 4, 2026 to the latest update

Reports linked to Lake Washington

Reports linked to Lake Washington, newest first
WhenReportStatus
to Sep 27, 2:22 AMSeattle Public Utilities · 8700 Block of Sandpoint Way NE, Seattle · SSO · 18,100 gallons report · notice · mapended

Sources: Washington Ecology Sewage Spills list (RCW 90.48.636 public website), retrieved 2026-11-06 06:01 UTC. A report's record id and times show when you hover or focus its "report" link.

Download these reports as CSV

All reports in Washington by year: 2026 (1 here)

Wastewater outlets on this water

Combined sewer outfalls

43 outfalls · 4 closed · discharge possible now at 5

Discharge possible: heavy rain, no report received at 5 outfalls now: radar rainfall has reached the operator's threshold and no discharge report has arrived (NOAA radar estimate).

Showing 12 of 43.

Source: U.S. Environmental Protection Agency (EPA) national combined sewer outfall inventory (ECHO) and state outfall layers. Open or closed as EPA's inventory lists it. DirtyWaterWatch links outlets to waters using permit numbers, locations and names.

Sewer operators listed for this water: King County Wastewater Treatment Division (West Point, South, Brightwater, Vashon and Carnation plants and King County's CSOs), Seattle Public Utilities (combined sewer system), Sound Transit (East Link construction stormwater permit in EPA's CSO inventory).

Boat launches

Source: OpenBoatLaunch launch records (public agency data and OpenStreetMap, Open Database License). · Lake Washington on OpenBoatLaunch

Nearby waters

Sources covering this water

1 record linked to this water. Updated .