Owler Lane CSO

Storm overflow run by Yorkshire Water, discharging into Bagley Dyke.

Storm overflow on the sewer network Sheffield Brightside and Hillsborough constituency
Right now
Not discharging
Last discharge ended on (14 hours ago).
Times are UK time. Company feed updated just now

"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.

2026 so far
53spills
517 h discharging on 50 days · counted by us, not yet official
2025 official
73spills
290 h · +18% on 2024
Rank in Yorkshire Water
#112
of 2,161 overflows by 2025 spills (1 = most)
Monitor in 2025
100% working
Long-term average 63.3 spills a year

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 and the live feed. The official figure is published next spring.

2021
63 spills · 167 hmonitor 99.7%
2022
60 spills · 157 hmonitor 98.3%
2023
76 spills · 228 hmonitor 100%
2024
62 spills · 237 hmonitor 100%
2025
73 spills · 290 hmonitor 100%
2026so far
53 spills · 517 h

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 Bagley Dyke. They share the sewer and the storm, so one outlet's figures are only part of what reaches the water.

83m Dunmow Road CSOYWS01935Dunmow Road/CSO 1spill in 2025

This overflow: 73 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 review
Not asset maintenance - hydraulic capacity
Investigation
UWWTR investigation ongoing, Operational investigation completed
Improvement work
No improvement action in reporting period
Monitored since
2020
Water body
Don from River Loxley confl to River Don Works

This overflow spilled often enough to trigger the EA's high-spill review; the review line is the company's own stated reason.

Discharges we have recorded

218 discharge periods since 1 Jan 2024. 210 of them come from Yorkshire Water's own event-duration-monitoring records (published on Stream, Jan 2024 – Aug 2026); the live feed adds anything after that. The official annual count is the figure to quote.

Show 30 earlier (of 218)
StartedEndedDischarge time
15 min
14 h 20 min
9 h 10 min
2 h 42 min
30 min
45 min
15 min
32 min
58 min
12 h 53 min
15 min
15 min
30 min
5 h 27 min
9 h 28 min
9 h 15 min
30 min
36 min
15 h 17 min
19 h 0 min
12 h 34 min
19 h 31 min
7 h 43 min
4 d 21 h
1 h 30 min
21 h 56 min
15 h 29 min
1 d 10 h
15 h 56 min
1 h 15 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 298 raw blocks were merged into 218 continuous discharge periods (gaps under 15 min joined).

What the feed showed

FloodRadar's own record of every change of state Yorkshire Water's live feed has shown for this overflow, kept since : 11 states. The feed publishes its status now and its latest discharge, nothing older; the discharges above are read from this. It is here so the figures can be checked.

Show the last 11 states
SeenStatusSinceLatest discharge
Not discharging →
Discharging → no end yet
Not discharging →
Discharging → no end yet
Not discharging →
Discharging → no end yet
Not discharging →
Discharging → no end yet
Not discharging →
Discharging → no end yet
Not discharging →

Rain nearby last 30 days

Nearest live rain gauge: Rainfall gauge nr Rotherham, 7.4 km away. Brown shading = when this overflow was discharging; ▼ = a discharge start.

Overflow shading is a timing match, not proof of cause — heavy rain and spills share a trigger. Times come from the water company’s event-duration monitor (site status only; no discharge volume is published).

Where it is

Nearest river gauge
Grimesthorpe (Bagley Dike) · 0.3 km
Nearest rain gauge
Council area
Sheffield District (B)
Site reference
YWS00884 · permit C5538
Coordinates
53.40739, -1.44038

Tell me when this overflow discharges

One message when the company's monitor reports a new discharge here. At most one every 6 hours.

Setting this alert needs JavaScript. The alerts you already have are on your alerts page.

The alert repeats the monitor's status: whether the overflow is discharging, not how much or why. It can only tell you about a discharge that starts after you turn it on.

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 Sheffield Brightside and Hillsborough 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.

Live status: © Yorkshire Water storm overflow activity data, licensed under CC BY 4.0. 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. Discharges marked "via Top of the Poops", come from Top of the Poops' record of the same company feed, used under CC BY-SA 4.0: the feed's own start and end times as its pages print them, not their derived hours. 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.