Overflow history upstream of River Great Ouse, Houghton Mill
The spot's forecast · For event organisers
This page lists the monitored storm overflows upstream of this spot and how often each spilled in each year. It is not a water test, and it does not say whether the water is fit to swim in. It does not include farm runoff, misconnected drains, treated sewage effluent, wildlife or overflows without a monitor. A year's count depends on how long the monitor worked, shown as monitor uptime.
Each year, all overflows upstream
| Year | Overflows with a return | Spills | Spill hours | Spill hours, weighted by reach |
|---|---|---|---|---|
| 2021 | 20 | 577 | 8,489 | 622 |
| 2022 | 30 | 590 | 5,501 | 141 |
| 2023 | 42 | 1,069 | 14,116 | 401 |
| 2024 | 43 | 1,864 | 26,238 | 1,686 |
| 2025 | 43 | 571 | 5,790 | 112 |
Reach is the share of a spill's bacteria SwimSignal's model expects to arrive here, after die-off on the way and dilution by the river. Weighting by it counts an hour of spilling just upstream for far more than one 40 km away. 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. How reach is worked out.
The overflows, by reach
All 44, the one whose spills matter most here first. Hours away is how long sewage takes to arrive at the model's river speed.
| Overflow and id | Company | km upstream | Hours away | Reach | Spills 2023 | Spills 2024 | Spills 2025 | Spill hours 2025 | Monitor uptime 2025 |
|---|---|---|---|---|---|---|---|---|---|
| Huntingdon (Godmanchester) sewage works overflow Huntingdon (Godmanchester) STW · AWS00631 | Anglian Water | 2.1 | 1 | 91% | 16 | 66 | 4 | 44 | 100% |
| Huntingdon Sapley Rd storm overflow Huntingdon Sapley Rd CSO · AWS01575 | Anglian Water | 3.1 | 2 | 86% | – | 5 | 0 | 0 | 15% |
| Hartford Road storm overflow Hartford Road Combined Sewer Overflow · AWS00564 | Anglian Water | 4.6 | 2 | 81% | 44 | 66 | 27 | 30 | 100% |
| St Neots sewage works overflow ST Neots STW · AWS01259 | Anglian Water | 18.5 | 10 | 23% | 2 | 8 | 6 | 2 | 100% |
| St. Neots, Market Square storm overflow St. Neots - Market Square CSO · AWS01258 | Anglian Water | 21.1 | 12 | 20% | 16 | 32 | 14 | 1 | 95% |
| Brampton pumping station overflow Brampton PS · AWS00124 | Anglian Water | 9.5 | 5 | 14% | 0 | 1 | 0 | 0 | 99% |
| Hail Weston-Ford End pumping station overflow Hail Weston-Ford END TPS · AWS01310 | Anglian Water | 23.6 | 13 | 6% | 0 | 21 | 5 | 15 | 100% |
| Great Staughton-Causeway pumping station overflow Great Staughton-Causeway TPS · AWS01359 | Anglian Water | 30.6 | 17 | 4% | 60 | 73 | 28 | 288 | 100% |
| Gt Staughton-Town Bridge storm overflow GT Staughton-Town Bridge OV · AWS01309 | Anglian Water | 31.1 | 17 | 3% | 1 | 31 | 1 | 1 | 95% |
| Kimbolton sewage works overflow Kimbolton STW · AWS00678 | Anglian Water | 32.6 | 18 | 3% | 80 | 116 | 33 | 221 | 100% |
| Spaldwick pumping station overflow Spaldwick TPS · AWS01208 | Anglian Water | 17.8 | 10 | 3% | 18 | 19 | 4 | 25 | 100% |
| Bedford sewage works overflow Bedford STW · AWS00073 | Anglian Water | 41.4 | 23 | 2% | 91 | 92 | 7 | 50 | 62% |
| Buckden sewage works overflow Buckden STW · AWS00164 | Anglian Water | 14.0 | 8 | 1% | 120 | 162 | 66 | 731 | 100% |
| Stonely Old Ford Lane storm sewage overflow 2 Stonely OLD Ford Lane SSO 2 · AWS01307 | Anglian Water | 35.9 | 20 | 1% | 40 | 62 | 25 | 169 | 47% |
| Kimbolton-George Lane storm sewage overflow Kimbolton-George Lane SSO · AWS00677 | Anglian Water | 35.9 | 20 | 1% | 3 | 30 | 1 | 0 | 100% |
| Tempsford sewage works overflow Tempsford STW · AWS01352 | Anglian Water | 28.7 | 16 | 1% | 33 | 25 | 20 | 295 | 98% |
| Kempston-Ibbetts Close pumping station overflow Kempston-Ibbetts Close SP · AWS00634 | Anglian Water | 50.7 | 28 | 1% | – | – | – | – | 0% |
| Kempston-Village Hall pumping station overflow Kempston-Village Hall PS · AWS00669 | Anglian Water | 51.0 | 28 | 1% | 0 | 0 | 0 | 0 | 100% |
| Molesworth sewage works overflow Molesworth STW · AWS00851 | Anglian Water | 27.6 | 15 | 1% | 31 | 40 | 13 | 154 | 98% |
| Godmanchester-White Hart pumping station overflow Godmanchester-White Hart TPS · AWS01488 | Anglian Water | 4.0 | 2 | 1% | 2 | 10 | 3 | 5 | 100% |
| Abbotsley-Harbins Lane pumping station overflow Abbotsley-Harbins Lane SP · AWS00007 | Anglian Water | 28.6 | 16 | 1% | 0 | 14 | 6 | 28 | 100% |
| Ellington-Grafham Road pumping station overflow Ellington-Grafham Road SP · AWS00397 | Anglian Water | 15.0 | 8 | 1% | 0 | 4 | 2 | 18 | 100% |
| Brampton sewage works overflow Brampton WRC · AWS00125 | Anglian Water | 8.5 | 5 | 1% | 11 | 60 | 7 | 56 | 100% |
| Waresley sewage works overflow Waresley STW · AWS01438 | Anglian Water | 31.0 | 17 | 0% | 67 | 50 | 12 | 139 | 100% |
| Offord Cluny-Station Lane pumping station overflow Offord Cluny-Station Lane TPS · AWS00951 | Anglian Water | 12.5 | 7 | 0% | 4 | 55 | 3 | 18 | 100% |
| Stukeley, Low Road pumping station overflow Stukeley - Low Road Terminal Pumping Station · AWS01327 | Anglian Water | 13.2 | 7 | 0% | 61 | 47 | 14 | 148 | 100% |
| Great Gidding pumping station overflow Great Gidding TPS · AWS00498 | Anglian Water | 30.2 | 17 | 0% | 0 | 73 | 2 | 4 | 100% |
| Pertenhall sewage works overflow Pertenhall STW · AWS00980 | Anglian Water | 36.7 | 20 | <1% | 99 | 165 | 80 | 1,273 | 99% |
| Great Gransden pumping station overflow Great Gransden TPS · AWS00500 | Anglian Water | 32.5 | 18 | <1% | 20 | 44 | 11 | 65 | 100% |
| Paxton sewage works overflow Paxton STW · AWS00979 | Anglian Water | 21.3 | 12 | <1% | 17 | 31 | 5 | 65 | 100% |
| Catworth-Hostel sewage works overflow Catworth-Hostel STW · AWS00210 | Anglian Water | 26.4 | 15 | <1% | 7 | 20 | 3 | 26 | 100% |
| Riseley sewage works overflow Riseley STW · AWS01052 | Anglian Water | 43.0 | 24 | <1% | 29 | 22 | 5 | 24 | 100% |
| Bromham-Village Road storm sewage overflow Bromham-Village Road SSO · AWS01116 | Anglian Water | 54.6 | 30 | <1% | 2 | 10 | 4 | 15 | 99% |
| Roxton sewage works overflow Roxton STW · AWS01069 | Anglian Water | 29.1 | 16 | <1% | 0 | 33 | 4 | 2 | 100% |
| Everton sewage works overflow Everton STW · AWS00419 | Anglian Water | 32.1 | 18 | <1% | 1 | 1 | 1 | 0 | 100% |
| Marston Moretaine sewage works overflow Marston Moretaine STW · AWS00823 | Anglian Water | 54.5 | 30 | <1% | 103 | 147 | 76 | 914 | 100% |
| Little Staughton sewage works overflow Little Staughton STW · AWS00753 | Anglian Water | 34.0 | 19 | <1% | 51 | 85 | 22 | 284 | 100% |
| Bolnhurst sewage works overflow Bolnhurst WRC · AWS00096 | Anglian Water | 32.6 | 18 | <1% | 17 | 82 | 40 | 611 | 100% |
| Swineshead (Beds) sewage works overflow Swineshead STW (Beds) · AWS01344 | Anglian Water | 40.8 | 23 | <1% | 0 | 4 | 1 | 0 | 100% |
| Marston-Station Road pumping station overflow Marston-Station Road TPS · AWS00824 | Anglian Water | 55.5 | 31 | <1% | 1 | 6 | 1 | 11 | 100% |
| Rushden-Court Estate pumping station overflow Rushden-Court Estate SP · AWS00285 | Anglian Water | 51.9 | 29 | <1% | 18 | 29 | 7 | 33 | 100% |
| Thurleigh-Church End pumping station overflow Thurleigh-Church END SP · AWS01378 | Anglian Water | 49.8 | 28 | <1% | 1 | 10 | 2 | 12 | 98% |
| Thurleigh sewage works overflow Thurleigh STW · AWS01379 | Anglian Water | 50.4 | 28 | <1% | 3 | 5 | 4 | 2 | 100% |
| Wilstead-Bedford RD Duck END AWS01316 | Anglian Water | 46.7 | 26 | <1% | 0 | 8 | 2 | 10 | 99% |
A dash: no annual return for that overflow in that year.
Sources and credits
Storm overflow annual returns: © Environment Agency copyright and/or database right 2025, Open Government Licence v3.0. Overflow positions: the water companies via the National Storm Overflow Hub, CC BY 4.0. River network: contains OS data © Crown copyright and database right 2026 (OS Open Rivers). Traced and weighted by SwimSignal (swimsignal.co.uk), whose method is at swimsignal.co.uk/methods.html. All credits and licences.