A FAMILY of swans died when they became trapped in a weir.
The parents and their four cygnets were discovered near Dorchester at Sydling Water.
It is believed they dropped through gaps in the weir and either starved or drowned.
A spokesman for Dorset Wildlife Trust said it was alerted by a member of the public and a recovery operation took place.
The adult swans were a known breeding pair and had produced five or six cygnets a year since 2009.
The Environment Agency has been asked to investigate the site to see if there is a danger to wildlife and what can be done.
A spokesman said: “Although we have no operational responsibility, we have been asked to have a look at the structure to see whether it is inherently unsafe for wildlife and whether we can make some recommendations.”
He said the agency is trying to find out who the site belongs to; it is believed to be owned by Dorset County Council’s highways department or Network Rail.
The river channel runs between the railway line and the A37 at Grimstone.
The spokesman added: “This family of swans has got in to this sump and couldn’t get out and unfortunately perished.”
It is believed a meeting will be held this afternoon at the site.
A Dorset Wildlife Trust spokesman said: “It’s very sad.
“A new channel has been put in recently because the weir is very high and didn’t allow migrating fish to come through, and it’s unusual for these swans to have gone down this old channel.
“The weir has been there for centuries and it’s the first time we have had something like this.
“A lot of investigation has gone on recently to find out who owns the weir.”