River Health
Scorecard
Tillingbourne Dippers
with Water Rangers
The River Wey Trust
PNTDSCLARPOLE. coliINNSINVHABOVERALLB76.1%
Overall score is the average of the six scored spokes. Grey spokes are not included yet.
River Tillingbourne
A snapshot of river health from a year of community sampling by the Tillingbourne Dippers, from Abinger Hammer down to Shalford. Water chemistry is tested on the riverbank and E. coli samples are processed at the Community Water Lab in Guildford.
120
site visits
12
sites
108
E. coli samples
RIVER HEALTH SCALE
A
Excellent
80–100
B
Good
60–80
C
Fair
40–60
D
Poor
20–40
F
Very poor
0–20
ID
Not enough data
 
Map of the River Tillingbourne from Guildford and Shalford east to Abinger Hammer and Wotton, with the main sampling sites markedAlbury Park Laundry (Riverfly, 2 samples)Wotton Estate (1 visit)Upstream from Bridge (1 visit)Shere Mill Red Cottage (1 visit)Near 'The Holiday' bridge (1 visit)Sammy’s snail Gunpowder Mills (3 visits)Raikes Lane Abinger Hammer (4 visits)Shere Swimming Pool Field (24 visits)Chilworth Gunpowder Mills (25 visits)Abinger Hammer Cricket Pitch (25 visits)Shalford Mill (29 visits)Sampling sitesRiverfly sites
Main sampling sites. Map: The River Wey Trust, Open Street Map base
Flows west into the River Wey at Shalford
WHAT EACH SPOKE MEANS
PPhosphate. Phosphate-phosphorus, Kyoritsu pack test. Score: share of samples at or under 0.05 mg/L.
NNitrate. Nitrate-nitrogen, Kyoritsu pack test. Score: share of samples at or under 2 mg/L.
TDSDissolved solids. From conductivity (pen meter). Score: share of samples at or under 400 µS/cm.
CLARClarity. Stands in for turbidity. Share of visual checks rated clear.
POLPollution. Share of surveys with no foam, scum, oily sheen, litter or odour. Storm overflow data still to add.
E. coliBacteria. Lab tests (IDEXX Colilert). Share of samples at or under 1,000 CFU/100 ml, the England bathing water figure.
INNSInvasive species. Invasive non-native plants. Recorded since July 2026, not scored yet.
INVInvertebrates. Riverfly samples: share at or above each site's trigger level.
HABHabitat. Needs a River Habitat Survey or MoRPh (Modular River Physical) survey.
Data: 17 Oct 2025 to 16 Oct 2026
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River Tillingbourne
Monthly averages, Oct 2025 to Oct 2026
Gaps mean no samples that month
The River Wey Trust
Phosphatemg/L as P0.00.10.20.30.40.5LowModerateHighONDJFMAMJJASOOct 2025Oct 2026Water temperature°C05101520ONDJFMAMJJASOOct 2025Oct 2026E. coliCFU per 100 ml01,0002,0003,0004,0005,0006,000ONDJFMAMJJASOOct 2025Oct 2026Bathing water 1,000Nitratemg/L as N0123456LowModerateHighONDJFMAMJJASOOct 2025Oct 2026
Is it safe to swim?
Share of samples at or under 1,000 CFU/100 ml, Apr to Oct 2026
Chilworth Gunpowder Mills
71% of 24 samples
Shalford Mill
50% of 26 samples
Shere Swimming Pool Field
25% of 24 samples
Abinger Hammer Cricket Pitch
20% of 25 samples
Where is it coming from?
DNA source tracking, one sample per site, 8 Aug 2026
Abinger Hammer Cricket Pitch
94%
Human: not detected
Shere Swimming Pool Field
67%
26%
7%
Human: not detected
Ruminant
Bird
Horse
Share of animal faecal DNA detected · Trace Biomonitoring
No human marker was found at either site. Most of what was found came from cows or sheep, and Abinger Hammer Cricket Pitch carried about six times more animal faecal DNA than Shere Swimming Pool Field. Two samples are a first look, not a pattern yet.
Also spotted: On the surface: foam (5); no odour in 22 checks; suspected sources noted: residential discharge (2), agricultural (2), highway discharge (1), farm / light industry (1), agricultural suspected & septic tank suspected (1), urban discharge (1), assume residential (1). Invasive plants: Himalayan balsam (1). Wildlife sightings aren't on the survey form yet.
Sources: Tillingbourne Dippers (Water Rangers) · Trace Biomonitoring
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River Tillingbourne
Along the river
Oct 2025 to Oct 2026
The River Wey Trust
From source to River Wey at Shalford
Each line follows one test down the river, joining the average at each site. Tests are shown as multiples of their scoring threshold so they can share one scale: anything above the red line is worse than the threshold. Hollow marks are sites with only one or two samples, so treat them with care. Sites are placed by distance along the river (17.9 km in all).
PhosphatePhosphate (threshold 0.05 mg/L)
NitrateNitrate (threshold 2 mg/L)
ConductivityConductivity (threshold 400 µS/cm)
E. coliE. coli (threshold 1000 CFU/100 ml)
1/201/101/41/21×2×5×10×20×50×Scoring thresholdRaikes Lane Abinger Hammer, Phosphate: average 0.035 mg/L, lowest 0.035, highest 0.035 (1 sample; threshold 0.05 mg/L)Abinger Hammer Cricket Pitch, Phosphate: average 0.0175 mg/L, lowest 0, highest 0.03 (4 samples; threshold 0.05 mg/L)Shere Swimming Pool Field, Phosphate: average 0.0183 mg/L, lowest 0, highest 0.035 (3 samples; threshold 0.05 mg/L)Sammy’s snail Gunpowder Mills, Phosphate: average 0.02 mg/L, lowest 0.02, highest 0.02 (1 sample; threshold 0.05 mg/L)Chilworth Gunpowder Mills, Phosphate: average 0.312 mg/L, lowest 0.05, highest 0.95 (4 samples; threshold 0.05 mg/L)Shalford Mill, Phosphate: average 0.0675 mg/L, lowest 0, highest 0.2 (4 samples; threshold 0.05 mg/L)Upstream from Bridge, Phosphate: average 0.1 mg/L, lowest 0.1, highest 0.1 (1 sample; threshold 0.05 mg/L)Raikes Lane Abinger Hammer, Nitrate: average 0.35 mg/L, lowest 0.35, highest 0.35 (1 sample; threshold 2 mg/L)Abinger Hammer Cricket Pitch, Nitrate: average 2.1 mg/L, lowest 1, highest 3.4 (4 samples; threshold 2 mg/L)Shere Swimming Pool Field, Nitrate: average 4 mg/L, lowest 0, highest 7 (3 samples; threshold 2 mg/L)Sammy’s snail Gunpowder Mills, Nitrate: average 2.17 mg/L, lowest 0.5, highest 5 (3 samples; threshold 2 mg/L)Chilworth Gunpowder Mills, Nitrate: average 1.8 mg/L, lowest 1, highest 2 (5 samples; threshold 2 mg/L)Shalford Mill, Nitrate: average 1.06 mg/L, lowest 0.5, highest 2 (4 samples; threshold 2 mg/L)Upstream from Bridge, Nitrate: average 2 mg/L, lowest 2, highest 2 (1 sample; threshold 2 mg/L)Raikes Lane Abinger Hammer, Conductivity: average 184 µS/cm, lowest 184, highest 184 (1 sample; threshold 400 µS/cm)Abinger Hammer Cricket Pitch, Conductivity: average 276 µS/cm, lowest 267, highest 297 (4 samples; threshold 400 µS/cm)Shere Swimming Pool Field, Conductivity: average 293 µS/cm, lowest 290, highest 297 (3 samples; threshold 400 µS/cm)Near 'The Holiday' bridge, Conductivity: average 297 µS/cm, lowest 297, highest 297 (1 sample; threshold 400 µS/cm)Sammy’s snail Gunpowder Mills, Conductivity: average 279 µS/cm, lowest 261, highest 294 (3 samples; threshold 400 µS/cm)Chilworth Gunpowder Mills, Conductivity: average 317 µS/cm, lowest 300, highest 352 (7 samples; threshold 400 µS/cm)Shalford Mill, Conductivity: average 294 µS/cm, lowest 284, highest 298 (4 samples; threshold 400 µS/cm)Upstream from Bridge, Conductivity: average 308 µS/cm, lowest 308, highest 308 (1 sample; threshold 400 µS/cm)Wotton Estate, E. coli: average 4.84e+03 CFU/100 ml, lowest 4.84e+03, highest 4.84e+03 (1 sample; threshold 1000 CFU/100 ml)Raikes Lane Abinger Hammer, E. coli: average 2.33e+03 CFU/100 ml, lowest 727, highest 4.84e+03 (4 samples; threshold 1000 CFU/100 ml)Abinger Hammer Cricket Pitch, E. coli: average 2.58e+03 CFU/100 ml, lowest 187, highest 2.42e+04 (25 samples; threshold 1000 CFU/100 ml)Shere Mill Red Cottage, E. coli: average 870 CFU/100 ml, lowest 870, highest 870 (1 sample; threshold 1000 CFU/100 ml)Shere Swimming Pool Field, E. coli: average 2.3e+03 CFU/100 ml, lowest 428, highest 1.73e+04 (24 samples; threshold 1000 CFU/100 ml)Near 'The Holiday' bridge, E. coli: average 1.66e+03 CFU/100 ml, lowest 1.66e+03, highest 1.66e+03 (1 sample; threshold 1000 CFU/100 ml)Chilworth Gunpowder Mills, E. coli: average 955 CFU/100 ml, lowest 237, highest 4.84e+03 (24 samples; threshold 1000 CFU/100 ml)Shalford Mill, E. coli: average 1.41e+03 CFU/100 ml, lowest 359, highest 4.84e+03 (26 samples; threshold 1000 CFU/100 ml) SourceRiver Wey at Shalford0 km2 km4 km6 km8 km10 km12 km14 km16 kmWotton Estate, 1.4 km1Raikes Lane Abinger Hammer, 4.3 km2Abinger Hammer Cricket Pitch, 5.6 km3Shere Mill Red Cottage, 7.9 km4Shere Swimming Pool Field, 8.1 km5Near 'The Holiday' bridge, 8.7 km6Sammy’s snail Gunpowder Mills, 13.8 km7Chilworth Gunpowder Mills, 13.9 km8Shalford Mill, 17.3 km9Upstream from Bridge, 17.8 km10
1  Wotton Estate (1.4 km)
2  Raikes Lane Abinger Hammer (4.3 km)
3  Abinger Hammer Cricket Pitch (5.6 km)
4  Shere Mill Red Cottage (7.9 km)
5  Shere Swimming Pool Field (8.1 km)
6  Near 'The Holiday' bridge (8.7 km)
7  Sammy’s snail Gunpowder Mills (13.8 km)
8  Chilworth Gunpowder Mills (13.9 km)
9  Shalford Mill (17.3 km)
10  Upstream from Bridge (17.8 km)
River line: Ordnance Survey Open Rivers, contains OS data © Crown copyright and database right
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River Tillingbourne
The wider picture
The River Wey Trust
Environment Agency (EA) Ecological Status
Ecological status is the Environment Agency's official assessment of river health, based on plants, animals, water quality and the shape of the river, on a five-point scale from high to bad. It uses different measures and timescales from this community scorecard, so the two will not always agree. Together they give a fuller picture.
Classification data © Environment Agency.
See the full classification: environment.data.gov.uk/catchment-planning/WaterBody/GB106039017840
Riverflies
Volunteers count eight groups of pollution-sensitive invertebrates in a timed kick sample. Each site has a trigger level set with the Environment Agency: a score below it suggests a pollution problem. No trigger breaches in this period.
Albury Park Laundry
2 samples, latest 9 (trigger 8*)
13 other sites not sampled this period (most recently At bridge to Shere water works, Jul 2022).
Dipped below the trigger, now back above it
Average score by month
246810JanFebMarAprMayJunJulAugSepOctNovDec
Average of the sites
Average trigger level
* No trigger level set for this site yet, so the usual level for the river is used. Riverfly data: The Riverfly Partnership, via Cartographer, Open Government Licence v3.
Sources: Environment Agency Catchment Data Explorer · The Riverfly Partnership
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