Alleviation of Low Flow (ALF) study
- EA ecology area
- Hertfordshire and North London
- Waterbody IDs
- Not supplied
- Catchments
- Colne
Alleviation of Low Flow (ALF) study fishing evidence · Hertfordshire and North London
What fish are in the Alleviation of Low Flow (ALF) study?
Monitoring has recorded 11 species across 4 surveyed sites on this water, between 1999 and 2000. These are survey records with dates. They do not establish what is present today, that the water is fishable, or that you have permission to fish it.
River evidence passport
Four signals, kept deliberately separate.
The passport shows identity, survey breadth, evidence freshness and trip constraints without turning unlike facts into an opaque “best river” score.
4 sites · 8 events
11 positive taxa aggregates are shown. More survey coverage is not a fishing-quality verdict.
Latest 7 Nov 2000
- Within 2 years
- 0 sites
- 3–5 years
- 0 sites
- 6–10 years
- 0 sites
- Older
- 4 sites
Permission is not established
Survey evidence carries no access boundary, permit, opening status, catch forecast or live safety signal. Resolve each before travelling.
Search current river conditions & alerts → Compare this evidence with another river → England coarse close season →Recorded species
What monitoring has found here
Ordered by how many sites on this water recorded the species. A species not listed has not been recorded by these surveys — which is not the same as being absent.
- 3-spined sticklebackGasterosteus aculeatus3 siteslatest 7 Nov 2000
- BullheadCottus gobio3 siteslatest 7 Nov 2000
- Stone loachBarbatula barbatula3 siteslatest 7 Nov 2000
- Pike varietiesEsox lucius2 siteslatest 27 Jun 2000
- 10-spined sticklebackPungitius pungitius1 sitelatest 12 May 1999
- ChubLeuciscus cephalus1 sitelatest 7 Nov 2000
- DaceLeuciscus leuciscus1 sitelatest 7 Nov 2000
- European eelAnguilla anguilla1 sitelatest 27 Jun 2000
- MinnowPhoxinus phoxinus1 sitelatest 7 Nov 2000
- PerchPerca fluviatilis1 sitelatest 7 Nov 2000
- Rainbow troutOncorhynchus mykiss1 sitelatest 14 May 1999
Surveyed sites on this water
4 shown, newest survey first
Provenance
Source and licence
- SourceEnvironment Agency Ecology & Fish Data
- LicenceOpen Government Licence v3.0
- Source copy retrieved23 Jul 2026
- Waterbody nameAs published by the Environment Agency
- Not assertedCurrent presence, access, permission, fishing quality or safety