One person has been arrested after a protest near a lake where waste ash will be dumped from a power station.
Pumping of waste into Thrupp Lake is due to start later this year
Environmental campaigners were protesting over plans by RWE Npower to fill Radley Lakes with waste ash from Didcot Power Station.
Members of the Save Radley Lakes pressure group hope to stop the preparatory work, which includes trimming the trees on the site.
A 40-year-old man was arrested on suspicion of aggravated trespass.
An Npower spokeswoman said: "Thrupp Lake is extremely necessary for us to continue generation of power."
The protesters have said they will continue their campaign to save the lakes and its wildlife and are looking for the backing of other environmental groups.
"The whole point of us using Radley in the last 25 years has been to dispose of ash," added the Npower spokeswoman.
"We currently recycle half the matter [ash] from our power station.
"Earlier this week, we started vegetation clearance and also ecological studies.
"We are removing the top layers of trees as the preparatory work for the lagoon and ahead of the bird nesting season."
Earlier this month, a group who were squatting were evicted from the site.