Stations are listed from source to mouth as the water flows, traced on the river map (OS Open Rivers) and the Environment Agency’s own links between its gauges. A distance “by river” is along the river, and is shown only where the map traces the path.
Streams and rivers with a gauge whose water joins the Tamar above one of its gauges, from the source down. Named streams without a gauge that have a page here are listed at the end.
Its water passes Greystone Bridge and every gauge below it on the Tamar. It does not pass Polson Bridge or the gauges above it.
Gauged streams joining the Lyd
River Thrushel: joins the Lyd above Lifton Park (its lowest gauge is 1.9 km by river above it). Gauges, source first: Hayne BridgeLow · TinhayNormal; and 1 more gauge further up (see its own page).
Named streams on the river map that flow into the Tamar and have no gauge of their own. Each has a page with what is known about it: the next gauge downstream, and any storm overflows or water-sampling points placed on it.
Alren Stream (joins about 5.4 km above Gunnislake)
Tala Water (joins about 5.1 km above Polson Bridge)
Storm overflows upstream
38 storm overflows are traced upstream of Gunnislake, the Tamar’s lowest gauge on the river map: on the Tamar itself, on its gauged tributaries, and on smaller streams that join above there.
0 report discharging now
35 not discharging
3 offline or silent: 0 monitor offline, 3 status unknown, 0 no live feed
Official figures for 2025, for the overflows traced upstream of Gunnislake: 2,286 spills over 27,022 hours in total, across the 35 that have a figure. 2 had no usable monitor data that year; 1 has no 2025 figure.
Each overflow is listed in the stretch above the first gauge its water reaches, from the source down, as on the Gauges tab. A stretch of the Tamar includes the smaller streams that join it there. Every overflow traced is listed here, each stretch in full. Back to the short lists →
Between Bridge Rule and Crowford Bridge2 overflows
Bridgerule Pscso/EONot discharging South West Water · into River Tamar (S) · 6.0 km by river above Crowford Bridge · 2025: 0 spills, 0 h
Bridgerule WwTWNot discharging South West Water · into River Tamar · 5.6 km by river above Crowford Bridge · 2025: 34 spills, 436 h
Between Crowford Bridge and Polson Bridge9 overflows
West Croft RoadNot discharging South West Water · into River Deer · 27.8 km by river above Polson Bridge · 2025: 72 spills, 257 h
Holsworthy (Derriton) STWNot discharging South West Water · into Coles Stream (S) · 27.6 km by river above Polson Bridge · 2025: 111 spills, 1,697 h · placed on the river by its position alone
Holsworthy (Derriton) STWNot discharging South West Water · into Coles Stream (S) · 27.6 km by river above Polson Bridge · 2025: 77 spills, 322 h · placed on the river by its position alone
Halwill Sewage Treatment WorksNot discharging South West Water · into (S) River Carey · 22.4 km by river above Polson Bridge · 2025: 85 spills, 1,014 h
Clawton STWNot discharging South West Water · into Trib Of River Claw(S) · 21.2 km by river above Polson Bridge · 2025: 12 spills, 8.1 h
Ashwater STWNot discharging South West Water · into (S) River Carey · 15.6 km by river above Polson Bridge · 2025: 104 spills, 856 h
Newport Industrial Estate CSONot discharging South West Water · into River Kensey · 2.4 km by river above Polson Bridge · 2025: 118 spills, 387 h
St Leonards WwTWNot discharging South West Water · into River Tamar · 220 m by river above Polson Bridge · 2025: 39 spills, 148 h
St Leonards WwTWNot discharging South West Water · into River Tamar · 220 m by river above Polson Bridge · 2025: 74 spills, 1,274 h
River Kensey, above Truscottjoins the Tamar above Polson Bridge1 overflow
Egloskerry STWNot discharging South West Water · into River Kensey (S) · 3.8 km by river above Truscott · 2025: 116 spills, 1,174 h
River Kensey, above Launcestonjoins the Tamar above Polson Bridge3 overflows
Tregadillet PSNot discharging South West Water · into River Kensey · 4.0 km by river above Launceston · 2025: 3 spills, 0.7 h
St Thomas Road CSONot discharging South West Water · into River Kensey · 160 m by river above Launceston · 2025: 5 spills, 1.7 h
#n/AStatus unknown South West Water · into River Kensey · 130 m by river above Launceston · 2024: 4 spills, 0.3 h
River Ottery, above Werringtonjoins the Tamar above Polson Bridge2 overflows
North Petherwin WwTWNot discharging South West Water · into River Ottery · 5.8 km by river above Werrington · 2025: 74 spills, 1,302 h
Yeolmbridge PSNot discharging South West Water · into Trib Of River Ottery · 2.7 km by river above Werrington · 2025: 96 spills, 354 h
River Lyd, above Lifton Parkjoins the Tamar above Greystone Bridge3 overflows
Bridestowe WwTWNot discharging South West Water · into River Lew · 17.6 km by river above Lifton Park · 2025: 74 spills, 1,259 h
Chillaton STWNot discharging South West Water · into Trib Of River Lyd (S) · 7.4 km by river above Lifton Park · 2025: 0 spills, 0 h
Lifton Wastewater Treatment WorksNot discharging South West Water · into River Thrushel · 1.1 km by river above Lifton Park · 2025: 0 spills, 0 h
River Thrushel, above Hayne Bridgejoins the Lyd3 overflows
Bratton Clovelly WwTW CSONot discharging South West Water · into Trib Of River Thrushel · 10.4 km by river above Hayne Bridge · 2025: 104 spills, 574 h
Lewdown Wastewater Treatment WorksNot discharging South West Water · into Tributary Of River Thrushel · 5.6 km by river above Hayne Bridge · 2025: 70 spills, 621 h
Lewdown Wastewater Treatment WorksNot discharging South West Water · into Tributary Of River Thrushel · 5.6 km by river above Hayne Bridge · 2025: 57 spills, 981 h
Between Greystone Bridge and Gunnislake11 overflows
South Petherwin Pscso/EONot discharging South West Water · into Lowley Brook (S) · 25.6 km by river above Gunnislake · 2025: 69 spills, 1,314 h
Beals Mill Pumping StationNot discharging South West Water · into A Tributary Of River Inny · 16.8 km by river above Gunnislake · 2025: 77 spills, 1,619 h
Beals Mill No 1 CSOStatus unknown South West Water · into River Inny · 16.7 km by river above Gunnislake · 2025: no data
Beals Mill No 2 CSOStatus unknown South West Water · into River Inny · 16.7 km by river above Gunnislake · 2025: no data
Beals Mill WwTWNot discharging South West Water · into River Inny · 16.7 km by river above Gunnislake · 2025: 125 spills, 1,868 h
Milton Abbot WwTWNot discharging South West Water · into Tributary Of The River Tamar · 13.8 km by river above Gunnislake · 2025: 83 spills, 1,455 h
Stoke Climsland STWNot discharging South West Water · into (S) Luckett Stream · 9.6 km by river above Gunnislake · 2025: 105 spills, 803 h · placed on the river by its position alone
Old Mill PSNot discharging South West Water · into Alren Stream · 7.9 km by river above Gunnislake · 2025: 25 spills, 99 h
Luckett Wastewater Treatment WorksNot discharging South West Water · into Alren Stream · 5.6 km by river above Gunnislake · 2025: 0 spills, 0 h
Latchley STWNot discharging South West Water · into River Tamar (S) · 2.8 km by river above Gunnislake · 2025: 42 spills, 604 h
Chilsworthy WwTWNot discharging South West Water · into River Tamar · 980 m by river above Gunnislake · 2025: 41 spills, 251 h
River Inny, above Bealsmilljoins the Tamar above Gunnislake4 overflows
Altarnun STW (Storm Tank)Not discharging South West Water · into Penpont Water · 20.7 km by river above Bealsmill · 2025: 165 spills, 3,295 h
Lewannick STWNot discharging South West Water · into Penpont(S) · 14.4 km by river above Bealsmill · 2025: 2 spills, 1.9 h · placed on the river by its position alone
Polyphant Pscso/EONot discharging South West Water · into River Inny (S) · 14.1 km by river above Bealsmill · 2025: 132 spills, 1,731 h
Trebullett STWNot discharging South West Water · into The River Inny · 4.2 km by river above Bealsmill · 2025: 95 spills, 1,319 h
Near these gauges, connection not known
Within 3 km of one of the Tamar’s gauges in a straight line, but the river map cannot say whether their water reaches it.
Scarne Industrial Estate Pscso/EONot discharging South West Water · into Lowley Brook (S) · 2.0 km from Polson Bridge in a straight line · no mapped watercourse close enough to be sure · 2025: 24 spills, 179 h
Gunnislake WwTWNot discharging South West Water · into River Tamar (Estuarine) · 2.0 km from Gunnislake in a straight line · discharges to the sea, an estuary or tidal water · 2025: 72 spills, 440 h
Gunnislake WwTWNot discharging South West Water · into River Tamar (Estuarine) · 2.0 km from Gunnislake in a straight line · discharges to the sea, an estuary or tidal water · 2025: 94 spills, 956 h
Lawhitton WwTW CSONot discharging South West Water · into Trib Of River Tamar · 2.2 km from Greystone Bridge in a straight line · its watercourse is not on the river map · 2025: 12 spills, 26 h
Pyworthy Sewage Treatment WorksNot discharging South West Water · into Derril Water(S) · 2.7 km from Bridge Rule in a straight line · its recorded watercourse is not the one mapped beside it · 2025: 146 spills, 2,920 h
Derril SPSNot discharging South West Water · into River Derril (S) · 3.0 km from Tamarstone Bridge in a straight line · its watercourse is not on the river map · 2025: 89 spills, 754 h
3 other overflows within 3 km of these gauges are placed below the Tamar’s lowest gauge or on another river, so not listed.
Dated samples taken by the Environment Agency, not live readings. Results are published days to months after the sample is taken, and many points are sampled only a few times a year, or have not been sampled for years.
147 sampling points on the River Tamar and the streams that join it above Gunnislake, and below it. 54 have a sample from the last 12 months; 82 have any sample banked.
Sampled most recently, anywhere on the Tamar and its streams:
Small Brook at Youldon BridgeSmall Brook · 5.3 km above Bridge RuleLast sampled 29 Sep 2026 · 9 days agoOxygen 88.7%Temp 14.2 °CpH 7.66Ammonia below 0.03 mg/l
River Carey at Heale BridgeRiver Carey · 2.3 km above Polson BridgeLast sampled 28 Sep 2026 · 10 days agoOxygen 84.7%Temp 13.4 °CpH 6.36Ammonia below 0.03 mg/l
River Tamar at Dexbeer BridgeRiver Tamar · 6.4 km above Tamarstone BridgeLast sampled 28 Sep 2026 · 10 days agoOxygen 93.8%Temp 13.6 °CpH 6.36Ammonia below 0.03 mg/l
England's samples only. Each count opens the list of those points, nearest first, with the date of each one’s latest sample (the gauge’s “Upstream of here” list).
FloodRadar does not grade these results: there is no overall score, and official river classifications are a separate dataset. A sample taken downstream of an overflow does not by itself show where anything in it came from. River connections and distances are traced on OS Open Rivers (edition 2026-04), which leaves out many small channels.
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