Cragg Top storm overflow
Yorkshire Water · Cragg Top/CSO · YWS00277
This page collects what public records say about one storm overflow: its permit, how often it spilled, and the improvements recorded for it. It is not a water test and does not say whether the water is fit to swim in. A spill count is not a finding that the overflow broke its permit: overflows may spill in heavy rain under their permits, and nothing here can tell whether a spill was allowed.
The record
| Company | Yorkshire Water |
|---|---|
| Environment Agency id | YWS00277 |
| Name in the company's return | CRAGG TOP/CSO |
| Permit reference | 27/21/0263, activity 1 (2025 return) |
| Type | SO on sewer network |
| Discharges to | River Nidd (water body: Nidd from Low Bridge on Briggate (Knaresborough) to Crimple Beck) |
| Bathing water named in the return | Nidd at the Lido, Knaresborough |
The permit reference is as the Environment Agency's annual returns give it. The EA's consents register holds the permit itself, but its licence allows internal use only, so its conditions are not published here.
Swim spots downstream
SwimSignal counts this overflow at 1 swim spot. km is along the river network, through any lake on the way. The model weight is SwimSignal's estimate of how much this overflow's spills count at that spot, not a measurement (how it is worked out).
- Nidd at the Lido, Knaresborough · 1.7 km upstream · model weight 92% · every overflow there
Spills each year
| Year | Spills | Spill hours | Monitor uptime |
|---|---|---|---|
| 2021 | 19 | 5.25 | 99.51% |
| 2022 | 12 | 4 | 100% |
| 2023 | 15 | 5.25 | 99.33% |
| 2024 | 13 | 5 | 98.32% |
| 2025 | 11 | 106 | 95.69% |
From the water company's annual return to the Environment Agency, as published: the spill count as the company returned it, and the hours as the Environment Agency works them out from the return's total duration, to two decimal places. Spills are counted by the Environment Agency's 12/24 method: any discharge in the first 12 hours counts as one spill, then one more for each 24 hours with any discharge. A dash: no return for that year. Monitor uptime is the share of the year the monitor worked; a year with low uptime may undercount.
Recent spills
When this page was updated (31 Oct 2026, 20:24), its company's live feed showed it not discharging. The last spill the feed reported ended on 30 August 2026.
How long its spills lasted, 2024 and 2025. How long this overflow's spills lasted in 2024 and 2025, from the water company's monitor records published by the Environment Agency. A record of the past, not a forecast. It says nothing of how much was discharged.
| Typical spill | 15 min |
|---|---|
| Long end | 1.5 h |
| Longest | 4.4 days |
| Spills 2024 | 14 |
| Spills 2025 | 7 |
Typical: half its spills were shorter, half longer. Long end: one in ten lasted longer. A spill here is the monitor's events joined when they overlap or start less than an hour apart, so these counts differ from the annual returns' above. More on spill lengths.
Each spill's start and stop times: not listed here. The Environment Agency publishes them for 2024 on, under the Open Government Licence (its start/stop files); this page gives only the summary above. Yorkshire Water publishes its own files from 2021; they carry no licence, so SwimSignal does not use them.
Improvements recorded
| Return year | Improvement activity | Investigation activity |
|---|---|---|
| 2024 | No improvement action in reporting period | No investigation activity in reporting period |
| 2025 | No improvement action in reporting period | UWWTR investigation ongoing, Operational investigation completed, Bathing Water and/or Shellfish Water investigation ongoing |
Word for word from the annual returns. The 2023 return left these columns empty. A year's entry covers that year only; work under way may not show until a later return.
The Environment Agency's PR24 Water Industry National Environment Programme (WINEP) lists this action on this overflow's permit. The date is the date the action should be delivered, a deadline, not a record that it was:
- CRAGG TOP/CSO (08YW100679, EnvAct_IMP3): due 31 March 2030.
Not published here: Water UK's National Storm Overflows Plan, whose terms forbid reuse without written permission.
Send this record
The button opens your own email app with a short, factual draft about this overflow and a link to this page. Read it, change it as you wish, and add the address yourself: SwimSignal sends nothing and keeps no copy.
Yorkshire Water's own contact details are on its contact page. To send the same record to your MP, find your MP on the UK Parliament website.
The draft
Storm overflow Cragg Top storm overflow (YWS00277) Dear Yorkshire Water, I am writing about your storm overflow Cragg Top storm overflow (Environment Agency id YWS00277, permit 27/21/0263). It is upstream of Nidd at the Lido, Knaresborough, where people swim. Your annual returns to the Environment Agency record 2024: 13 spills, 5 hours; 2025: 11 spills, 106 hours. Your 2025 return lists its improvement activity as: "No improvement action in reporting period". The Environment Agency's PR24 WINEP sets 31 March 2030 as the date for the action "CRAGG TOP/CSO" (08YW100679). Could you tell me what is planned for this overflow, and when the work is expected to be finished? The public record I am referring to is here: https://swimsignal.co.uk/overflow/YWS00277/ Thank you.
Sources and credits
Storm overflow annual returns, including permit references and improvement and investigation activity: © Environment Agency copyright and/or database right, Open Government Licence v3.0; the figures are the water companies' own returns. PR24 Water Industry National Environment Programme: © Environment Agency copyright and/or database right 2025. All rights reserved. Published under the Open Government Licence. Spill lengths: Environment Agency storm overflow EDM start/stop data 2024 and 2025, Open Government Licence v3.0. Live status: the water companies via the National Storm Overflow Hub, CC BY 4.0. Spots, distances and model weights: SwimSignal, traced on OS Open Rivers (contains OS data © Crown copyright and database right 2026). Sources: annual returns, PR24 WINEP, start/stop data, National Storm Overflow Hub. All credits and licences.