PC Nathan Lucy swam out after the woman, who'd jumped into the water from the Red Jet terminal.
Dorset Beaches Fail Water Quality Tests
One of the wettest summers on record has led to lots more beaches around the UK including in Dorset failing water quality'tests
Two at Lyme Regis and one at Kimmeridge Bay missed out in the latest Good Beach Guide which says sewage, being washed into the sea, is to blame.
In total, 42 beaches around the UK failed to meet minimum European water quality standards - a rise of 17, on 2011's figures.
Coastal pollution officer for the Marine Conservation Society Rachel Wyatt said: "We have recommended fewer beaches in every English region and in Wales and Scotland. In England, the north west and south west were particularly badly hit with the fewest number of recommended beaches for at least a decade.
"Action must be taken now. With stricter bathing water standards from 2015 and summers that appear to be getting wetter, the iconic image of people bathing off golden beaches could be at serious risk.
"There is no simple solution to sewage and animal waste reaching our seas. However if the water industry, communities and local authorities recognise that there is a problem and begin to work together to find answers that would be a significant start.''
The MCS said there were some promising local partnerships working together to identify problems and start trying to fix them, but in too many places there was an "out of sight, out of mind mentality'' over water pollution.
The situation is a turn around from last year, when a record number of beaches were given the top "recommended'' award for their water quality.
Lyme Regis and Charmouth councils say they are working to tackle poor bathing water quality.
Dad-of-two Nick Medlin from Ventnor died after being assaulted outside the Rose Inn pub in the town.
A section of Parkstone Road will be affected between 9.30am and 4.30pm for three days.
A man's died in hospital after a crash in Eastleigh.
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