Historic monitoring evidence · Environment Agency
Denham
Hertfordshire and North London · survey site
This page records ecological survey evidence. It is not proof of current fish presence, abundance, fishing quality, access, permission or safety at this location.
Separate-signal passport
What this record proves — and what it does not.
No blended quality score. Identity, monitoring, freshness, access and rules stay as separate signals so one strong fact cannot hide a missing one.
Stable monitoring site
- AnglerRadar ID
- ea-fish-site:10253
- EA waterbody ID
- GB106039023090
- Waterbody
- Colne
- Catchment
- Colne
Dated survey record
- Scope
- freshwater
- Survey events
- 11
- Positive taxa shown
- 20
- Recorded methods
- DC ELECTRIC FISHING · ELECTRIC FISHING · PDC ELECTRIC FISHING
Latest survey about 11 years ago
Coverage runs from 20 Oct 1998 to 16 Jul 2015. This is historic monitoring, never a live presence or catch forecast.
Access remains unresolved
The survey carries no fishing-rights boundary, permission, opening status or safety notice. Check the owner, rod licence, current byelaws and conditions separately.
Location protection: AnglerRadar does not print the survey coordinate on this page, and nearby API results use coarsened survey areas rather than exact species-linked points.
Observed taxa
What monitoring recorded here
Taxa are ordered by latest survey date. Counts and records reflect monitoring events, not an angling forecast.
Roach
Rutilus rutilus- First record
- 20 Oct 1998
- Latest record
- 16 Jul 2015
- Survey events
- 8
Bullhead
Cottus gobio- First record
- 8 Sept 2003
- Latest record
- 16 Jul 2015
- Survey events
- 7
Minnow
Phoxinus phoxinus- First record
- 1 Dec 2004
- Latest record
- 16 Jul 2015
- Survey events
- 4
Perch
Perca fluviatilis- First record
- 20 Oct 1998
- Latest record
- 26 Jun 2012
- Survey events
- 9
Dace
Leuciscus leuciscus- First record
- 20 Oct 1998
- Latest record
- 26 Jun 2012
- Survey events
- 5
European eel
Anguilla anguilla- First record
- 18 Nov 2005
- Latest record
- 26 Jun 2012
- Survey events
- 5
Pike
Esox lucius- First record
- 20 Oct 1998
- Latest record
- 26 Jun 2012
- Survey events
- 4
Bleak
Alburnus alburnus- First record
- 18 Nov 2005
- Latest record
- 26 Jun 2012
- Survey events
- 3
Brown / sea trout
Salmo trutta- First record
- 5 Oct 2006
- Latest record
- 3 Aug 2010
- Survey events
- 2
Barbel
Barbus barbus- First record
- 5 Oct 2006
- Latest record
- 1 Aug 2009
- Survey events
- 4
Gudgeon
Gobio gobio- First record
- 20 Oct 1998
- Latest record
- 1 Aug 2009
- Survey events
- 4
Pike varieties
Esox lucius- First record
- 29 Jul 2008
- Latest record
- 1 Aug 2009
- Survey events
- 2
Chub
Leuciscus cephalus- First record
- 1 Dec 2004
- Latest record
- 29 Jul 2008
- Survey events
- 4
European eels > elvers
Anguilla anguilla- First record
- 1 Dec 2004
- Latest record
- 9 Aug 2007
- Survey events
- 2
Ruffe
Gymnocephalus cernuus- First record
- 9 Aug 2007
- Latest record
- 9 Aug 2007
- Survey events
- 1
Silver bream
Abramis bjoerkna- First record
- 9 Aug 2007
- Latest record
- 9 Aug 2007
- Survey events
- 1
Common bream
Abramis brama- First record
- 1 Dec 2004
- Latest record
- 5 Oct 2006
- Survey events
- 2
Tench
Tinca tinca- First record
- 1 Dec 2004
- Latest record
- 5 Oct 2006
- Survey events
- 2
Roach x common bream hybrid
Rutilus rutilus x Abramis brama- First record
- 18 Nov 2005
- Latest record
- 18 Nov 2005
- Survey events
- 1
3-spined stickleback
Gasterosteus aculeatus- First record
- 1 Dec 2004
- Latest record
- 1 Dec 2004
- Survey events
- 1
Rules and access
Check before you travel.
Environment Agency ecology records do not carry fishing-rights boundaries or live restrictions. Confirm the fishery owner, permission, local byelaws, seasonal rules, safety notices and current conditions before setting out.
Check live freshwater fishing rulesProvenance
Source, licence and boundary
- SourceEnvironment Agency Ecology & Fish Data
- LicenceOpen Government Licence v3.0
- Source copy retrieved23 Jul 2026
- Terms checked23 Jul 2026
- CoverageHistoric monitoring evidence, separately dated per record
- Not assertedCurrent presence, access, permission, fishing quality or safety
More evidence nearby
Other surveyed waters in Hertfordshire and North London.
409 survey sites in this ecology region carry recorded taxa. Each keeps its own dates and source.
Browse Hertfordshire and North London survey sites →