Signal crayfish are causing environmental problems in the River Colne, and its population needs to be controlled.

The invasive species burrow into the river and canal banks, causing erosion, bank collapse and sediment pollution.

They also feed on a variety of fish, frogs, invertebrates, and plants, and even eat each other.

The crayfish are currently controlled with traps which are adapted so other fish are not caught. But they are hard to manage due to population bursts when the female crayfish have their eggs fertilised in October.

As part of a 10-year project to rejuvenate the River Colne, Watford Borough Council and The Colne Catchment Action Network are hoping to come up with a consistent river scheme to trap smaller crayfish and stop the bursts of new crayfish in March next year.

Hillingdon Times:

Signal crayfish cause environmental problems in the River Colne. Photo: Simon Jacobs

The newly launched scheme addresses a range of other issues, including improving biodiversity, increasing water quality, reducing pollution and making the area more accessible and inviting.

A key part to the project will be harnessing a volunteer force who can carry out support activities including water monitoring.

River fly testing - which looks at the population sizes of flies - gives a good indication of the water quality in the river.

Hillingdon Times:

Mayor Peter Taylor holding up a crayfish, which is an invasive species. Photo: Simon Jacobs

Eight different types of species are monitored throughout the year, information is then sent to the Environment Agency to assess to see what can be done about the quality.

According to project leaders, water pollution is caused when waste water from nearby houses and businesses makes its way into the river.

Habitat and access improvements will also be made in Knutsford Playing Fields, Radlett Road Playing Fields, Waterfields Recreation Ground, Oxhey Park, Riverside Recreation Ground, Riverside Park, Timberlake Allotments and the Lairage Land.

Hillingdon Times:

The project hopes to restore the River Colne to its former glory. Photo: Simon Jacobs

Elected Mayor Peter Taylor said: “We are blessed to have many green spaces, rivers and canals that provide open space for Watford residents. However, the Colne, which flows through so many key sites in our town, has been neglected.

“I promised during my election campaign I would take positive action to restore the river and its habitat back to how it once was.

“I look forward to seeing people enjoying the river and cycling on the riverbank in the not too distant future.”

Environmental charity Groundwork has been appointed to lead the first phase of the project to "re-discover the River Colne".

Groundwork project officer Sam Harbour said: “This is an exciting project that is currently in its infancy with the scope to become something really great.

Hillingdon Times:

Watford Borough Council and The Colne Catchment Action Network are working together to rejuvenate the River Colne. Photo: Simon Jacobs

“We’re looking forward to improving the health and biodiversity of the river Colne as well as restoring and instilling it as a community resource.”

The council are also working with partners Community Connection Projects (CIC), the Environment Agency, Friends of Oxhey Park, Green Gym, Herts and Middlesex Wildlife Trust, the Colne Valley Fisheries Consultative.

Groundwork will be consulting with community organisation and people to find out what activities are currently on offer in and around the offer and what they would like to see in the future.

To share your thoughts, visit: www.surveymonkey.co.uk/r/rivercolne2019