Grosvenor Terrace CSO
Storm overflow run by Yorkshire Water, discharging into River Ouse.
"Not discharging" means the company's monitor reports no discharge right now — not that the water is clean. The feed publishes status only; no discharge volume is measured.
Year by year
The Environment Agency's official annual returns, counted the EA's way (12/24-hour spills). 2026 is our own running count, the same way, from Yorkshire Water's monitor log. The feed reports only each overflow's latest discharge, so a discharge it moved past before we saw it end is counted as one spill with no hours: the hours are a floor. The official figure is published next spring.
A spill is the EA's 12/24-hour count: the first 12 hours of a discharge count as one, each further 24 hours with discharge as one more. "Monitor" is the share of that year the monitor was working, so a 0 beside a working monitor is a real zero; "no data" means the monitor produced no usable data that year — not zero. Years before 2024 are matched to this site by name and location, because the EA's site IDs changed that year; a monitor figure beside one of them means the outlet's permit confirms the match.
Twin outlet
Yorkshire Water runs another overflow within 300 m that also discharges into River Ouse. They share the sewer and the storm, so one outlet's figures are only part of what reaches the water.
This overflow: 10 spills in 2025. Distances are between the published outlet points.
What the 2025 return says
From Yorkshire Water's annual return to the Environment Agency for this overflow.
"High spill threshold not met" means this overflow did not spill often enough to trigger the EA's formal high-spill review for that year. It is not a statement that the spills were harmless.
Discharges we have recorded
40 discharge periods since 10 Feb 2024, 4 whose end the feed never gave. 33 of them come from Yorkshire Water's own event-duration-monitoring records (published on Stream, Feb 2024 – Aug 2026); this overflow has no live feed, so nothing after that log is held. The official annual count is the figure to quote.
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3 min
-
43 min
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1 min
-
1 min
-
not captured
-
6 h 0 min
-
14 min
-
1 min
-
0 min
-
20 min
Show 30 earlier
| Started | Ended | Discharge time |
|---|---|---|
| 10 min | ||
| 4 min | ||
| 20 min | ||
| 32 min | ||
| 6 min | ||
| 56 min | ||
| 14 min | ||
| 1 h 22 min | ||
| 16 min | ||
| 18 min | ||
| 16 min | ||
| 38 min | ||
| 1 h 14 min | ||
| 14 min | ||
| 34 min | ||
| 4 min | ||
| 28 min | ||
| 34 min | ||
| 46 min | ||
| 2 min | ||
| 14 min | ||
| 1 h 0 min | ||
| 12 min | ||
| 10 min | ||
| 8 min | ||
| 36 min | ||
| 14 min | ||
| 24 min | ||
| 8 min | ||
| 18 min |
The year figures above use the EA's 12/24-hour counting method, so they are comparable with the official figures; the monitor log's 66 raw blocks were merged into 40 continuous discharge periods (gaps under 15 min joined).
Where it is
Concerned about this overflow?
Report pollution you can see or smell to the regulator straight away; the company handles complaints about the overflow itself.
Write to the MP
The Environment Agency's return places this overflow in the Selby constituency. An MP can ask the company and the regulator questions on a constituent's behalf. These words carry the official figures; change them as you like.
The link opens Parliament's own "Find your MP", which gives the MP's name and how to write to them. FloodRadar sends nothing and keeps nothing you write. Check the constituency against your own address: an MP acts only for people who live in it.
Annual spill figures: Environment Agency Event Duration Monitoring return, © Environment Agency copyright and/or database right, Open Government Licence (OGL) v3.0. Storm-overflow spill events: © the respective water company, published on Stream (data.streamwaterdata.co.uk) under CC BY 4.0. Discharges marked "EA start/stop data": Environment Agency Event Duration Monitoring storm overflow start/stop detailed data, © Environment Agency copyright and/or database right 2026, Open Government Licence v3.0; the companies' monitor records as the EA received them, not verified by the EA. Times are shown in UK local time. FloodRadar republishes the monitor's status and the EA's figures; it does not measure discharges itself. Constituency and council area from the EA's return: contains OS data © Crown copyright and database right 2026.