Historic monitoring evidence · Environment Agency
Hartham Common Weir
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.
Observed taxa
What monitoring recorded here
Taxa are ordered by latest survey date. Counts and records reflect monitoring events, not an angling forecast.
Chub
Leuciscus cephalus- First record
- 21 Jun 2018
- Latest record
- 21 Jun 2018
- Survey events
- 1
Dace
Leuciscus leuciscus- First record
- 21 Jun 2018
- Latest record
- 21 Jun 2018
- Survey events
- 1
Common bream
Abramis brama- First record
- 21 Jun 2018
- Latest record
- 21 Jun 2018
- Survey events
- 1
Roach
Rutilus rutilus- First record
- 21 Jun 2018
- Latest record
- 21 Jun 2018
- Survey events
- 1
Pike
Esox lucius- First record
- 21 Jun 2018
- Latest record
- 21 Jun 2018
- 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