Ynys Môn was polluted by sewage 3,331 times in 2024
lasting 28,615 hours - that's 3.31 years!

Constituency

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✔ means we have experimental daily data since 2023

Totals for Ynys Môn in 2024

77 Sites polluted by Dwr Cymru Welsh Water

3,331 sewage dumps
28,615 h duration

That's 3.31 years! On average 9.1 times a day

Change Over Time

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Your local MP is Llinos Medi (Plaid Cymru) - Find out more about their interests, donors, and voting at They Work For You

Constituencies near Ynys Môn

Waterways in Ynys Môn

Pollution Summary 2024

Here are all the reported sewage overflow totals for Ynys Môn in 2024. Sometimes sewage can be being dumped for months at a time.

Reporting refers to how much of the time the monitoring was active. In this constituency 0 of the total 86 CSO locations had reporting enabled for less than half the year, of which 0 had zero reporting.

Company	Waterway	Site	Sewage Dumps	Duration (Hours)	Reporting %
Dwr Cymru Welsh Water	Unnamed Ditch	LLANGAFFO CAE BERLLAN SPS	173	3,424	98.8
Dwr Cymru Welsh Water	Abberffraw Bay	ABERFFRAW WASTE WATER TREATMENT WKS	100	2,250	100
Dwr Cymru Welsh Water	River Goch	Craig Y Don SPS	158	2,075	99.8
Dwr Cymru Welsh Water	Menai Strait	LLANDEGFAN (MENAI) PUMPING STATION	106	1,942	99.9
Dwr Cymru Welsh Water	Unnamed Watercourse To River Goch	Rhosybol Gorslwyd PS	128	1,819	99.9
Dwr Cymru Welsh Water	Cadnant	PONT LLANDEGFAN SEWAGE PUMPING STAT	117	1,710	99.8
Dwr Cymru Welsh Water	Un-Named Watercourse	VALLEY STORM PS (GRAVITY DISCHARGE)	91	1,211	99.8
Dwr Cymru Welsh Water	Ditch	Hermon Malltraeth PS	84	1,189	96.1
Dwr Cymru Welsh Water	River Nodwydd	PENTRAETH STW	103	975	100
Dwr Cymru Welsh Water	Unnamed Draining To New Harbour	Porth y Felin Sewage Pumping Station	79	922	99.9
Dwr Cymru Welsh Water	River Meddanen	LLANFECHELL PUMPING STATION	82	870	99.9
Dwr Cymru Welsh Water	Menai Strait	BRYNSCIENCYN STW	81	842	99.9
Dwr Cymru Welsh Water	Menai Strait	BRYNSCIENCYN STW	79	823	100
Dwr Cymru Welsh Water	Estuarial Waters Of Holy Island Strait South	Four Mile Bridge SPS Holyhead	53	639	99.8
Dwr Cymru Welsh Water	Bull Bay	Bull Bay P.S.	83	566	99.9
Dwr Cymru Welsh Water	Menai Strait	PS NO 1 (FAELOG CAUSEWAY) (EMERGENC	63	460	99.9
Dwr Cymru Welsh Water	Coastal Waters	Llaneilian SPS	66	459	100
Dwr Cymru Welsh Water	Menai Strait	LLYN Y FELIN PS (EMERGENCY)	33	402	99.9
Dwr Cymru Welsh Water	Braint	Gaerwen Station SPS	41	399	99.5
Dwr Cymru Welsh Water	Menai Strait	Llanfair PG WwTW CSO	71	323	99.8
Dwr Cymru Welsh Water	Un-Named Watercourse	Valley Storm PS (Pumped Discharge)	72	283	99.8
Dwr Cymru Welsh Water	Coastal Waters	BENLLECH WWTW (STW) LSO BENLLECH	45	280	100
Dwr Cymru Welsh Water	Menai Strait	LLANFAES WWTW STORM TANK	41	278	99.8
Dwr Cymru Welsh Water	Menai Strait	PS NO 3 (SUSPENSION BRIDGE) (EMERGE	86	260	99.8
Dwr Cymru Welsh Water	River Briant	LLANDDANIEL PONT Y CRUG SPS	42	256	99.9
Dwr Cymru Welsh Water	Un-Named Watercourse	TREARDDUR BAY PS (GRAVITY)	40	250	98.6
Dwr Cymru Welsh Water	River Cadnant	Gorsllwyd Sewage Pumping Station	49	234	99.9
Dwr Cymru Welsh Water	Braint	DWYRAN RHYDWYN - SSO	27	225	13.3
Dwr Cymru Welsh Water	Braint	LLANFAIR PG SPS	31	223	99.9
Dwr Cymru Welsh Water	River Cefni	Llangefni Main Pumping Station	30	218	99.9
Dwr Cymru Welsh Water	Menai Strait	LLANFAES WWTW	31	200	99.8
Dwr Cymru Welsh Water	Esturial Waters Of Inland Sea	TREARDDUR BAY PS (PUMPED DISCHARGE)	57	189	99.8
Dwr Cymru Welsh Water	Llyn Maelog	BRYN DU SEWAGE PUMPING STATION	14	182	99.7
Dwr Cymru Welsh Water	Unnamed Stream	Llangaffo STW CSO	79	173	100
Dwr Cymru Welsh Water	Menai Strait	MOUNT FIELD P.S. BEAUMARIS ,	35	165	99.9
Dwr Cymru Welsh Water	Menai Strait	LLANFAIR PG WWTW	68	161	100
Dwr Cymru Welsh Water	New Harbour	Coastguard CSO	91	149	99.9
Dwr Cymru Welsh Water	Outer Harbour, Holyhead	Morawelon SPS	25	139	99.7
Dwr Cymru Welsh Water	River Goch	Storm Tank Army Cadet Centre CSO	34	132	99.9
Dwr Cymru Welsh Water	Cefni - Cefni Reservoir West	Lon Sardis CSO (BODFFORDD OPP CAPEL SARDIS)	63	128	98.7
Dwr Cymru Welsh Water	Old Harbour	Holyhead Wastewater Treatment Works SPS	57	123	99.9
Dwr Cymru Welsh Water	Coastal Waters Off Benllech, A	BENLLECH WWTW (STW) LSO BENLLECH	20	122	100
Dwr Cymru Welsh Water	Coastal Waters - Aberffraw Bay	ABERFFRAW WASTE WATER TREATMENT WKS	11	90	100
Dwr Cymru Welsh Water	Cefni Reservoir Bypass Channel	BODFFORDD SEWAGE TREATMENT WORKS	18	81	100
Dwr Cymru Welsh Water	Unnamed Ditch	TALWRN SPS	27	77	99.9
Dwr Cymru Welsh Water	Estuarial Waters Of River Alaw	Gorad PS Gorad NR Valley Anglesey	24	71	99.2
Dwr Cymru Welsh Water	Coastal Waters	MOELFRE PS MOELFRE	23	62	99.9
Dwr Cymru Welsh Water	Coastal Waters Of Irish Sea	CEMAES PS/BALANCING TANK CEMAES BAY	24	58	99.9
Dwr Cymru Welsh Water	Coastal Waters - Amlwch Harbour	Amlwch Port CSO	22	54	98.4
Dwr Cymru Welsh Water	Estuary Of River Braint	NEWBOROUGH STW	20	49	99.5
Dwr Cymru Welsh Water	Alan Catchment	RHOSYBOL PLAS Y FFRWD SPS	20	47	100
Dwr Cymru Welsh Water	River Braint	NEWBOROUGH STW	23	43	100
Dwr Cymru Welsh Water	River Braint	LLANGAFFO STW	62	38	100
Dwr Cymru Welsh Water	New Harbour	Hibernia Row Pumping Station	6	33	99.9
Dwr Cymru Welsh Water	Cadnant	LLANSADWRN PS	35	23	98.5
Dwr Cymru Welsh Water	Cefni	CSO Llangefni MH Front Ynys Mon Of	28	23	96.5
Dwr Cymru Welsh Water	River Cefni	LLANGEFNI WWTW STORM OVERFLOW	23	22	100
Dwr Cymru Welsh Water	Cefni Estuary	MALLTRAETH WWTW - STORM	27	22	100
Dwr Cymru Welsh Water	Adjacent Ditch	Llangefni Rhostrehwfa CSO	8	19	99.8
Dwr Cymru Welsh Water	Nant Nodwydd	PENTRAETH STW	16	16	100
Dwr Cymru Welsh Water	Unnamed Ditch	NEWBOROUGH MILLBANK SPS	3	13	62.2
Dwr Cymru Welsh Water	Cefni Reservoir By-Pass Channel	Bodffordd STW Settled Storm	3	11	100
Dwr Cymru Welsh Water	Nodwydd	PENTRAETH TAN Y GRAIG SPS	13	10	99.9
Dwr Cymru Welsh Water	Nant Cwyrtai	GWALCHMAI STW	10	10	100
Dwr Cymru Welsh Water	Menai Strait	BRYNSCIENCYN PS	3	10	99.8
Dwr Cymru Welsh Water	Adj Ditch	TREARDDUR BAY HAUL A MOR SPS	2	7	99.8
Dwr Cymru Welsh Water	Cefni Estuary	MALLTRAETH WWTW TERMINAL	7	6	100
Dwr Cymru Welsh Water	River Goch	Settled Storm Tank at Llanerchymedd STW	6	6	99.8
Dwr Cymru Welsh Water	Via A Drainage To River Clai	CSO at Llangefni MH Rear of Burgess	10	5	99.1
Dwr Cymru Welsh Water	Coastal Waters	RHOSNEIGR STW (SETTLED STORM/EMERGE	2	4	65.2
Dwr Cymru Welsh Water	Nant Cwyrtai	GWALCHMAI STW	3	3	100
Dwr Cymru Welsh Water	Coastal Waters	WENDON CAR PARK PS BENLLECH , , ,	5	3	88.2
Dwr Cymru Welsh Water	Cefni	MALLTRAETH VILLAGE CSO	4	2	78.8
Dwr Cymru Welsh Water	Menai Strait	PS NO 2 (PORTH WRACH) (EMERGENCY)	5	2	99.8
Dwr Cymru Welsh Water	New Harbour, Holyhead	WATERSIDE PUMPING STATION	5	1	99.6
Dwr Cymru Welsh Water	River Cefni	LLANGEFNI STW LLANGEFNI ANGLESEY	4	1	100
Dwr Cymru Welsh Water	Of Braint	LLANFAIRPWLL SSO NO. 2	1	0	60.1
Dwr Cymru Welsh Water	River Alaw	Bodedern Sewage Pumping Station	0	0	98.5
Dwr Cymru Welsh Water	River Alaw	Newlands Beach PS Valley Angle	0	0	99.9
Dwr Cymru Welsh Water	Unnamed Stream	GWALCHMAI ISAF PS	0	0	99.8
Dwr Cymru Welsh Water	Beddmanarch Bay	PENRHOS BEACH PUMPING STATION	0	0	98.9
Dwr Cymru Welsh Water	River Cadnant	LLANSADWRN PS	0	0	99.9
Dwr Cymru Welsh Water	River Ffraw	ABERFFRAW SPS GLAN Y MOR ABERFFRAW	0	0	99.9
Dwr Cymru Welsh Water	River Cefni	GAERWEN WWTW FINAL EFFLUENT	0	0	100
Dwr Cymru Welsh Water	Braint	DWYRAN BY SCHOOL - SSO	0	0	99.2
Dwr Cymru Welsh Water	River Cefni	Gaerwen WWTW Settled Storm	0	0	99.5

Data Sources & Accuracy

EDM (Event Duration Monitoring) data and Consented Discharges to Controlled Waters with Conditions from Environment Agency & Data Map Wales, and Scottish Water

Experimental derived data from Thames Water API, Some data may be missing or inaccurate. This uses Environment Agency rainfall data from the real-time data API (Beta) - Rainfall data is delayed by up to two days.

This website is intended to provide an accurate representation of the Environment Agency data. The data is hard to use, and thus some errors may have been made. If you find something that is incorrect, please raise an issue at the GitHub issues page and we'll endeavour to fix it quickly.

This project is not associated, approved or endorsed by any of the companies whose logos you see here.

Analysing sewage pollution by the Water Industry

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