Rainfall figures for the past week include 218mm at Tathra, 180mm at Narooma, 166mm at Bega and 108mm at Batemans Bay, most of the rain falling last Thursday and Friday.

The amazing downpours saw the 8980 megalitre Brogo Dam north-west of Bega swiftly go from 10per cent of its capacity on Thursday to full to overflowing by Friday.

Tuross Lake was reopened on Saturday afternoon after being closed to the ocean since December, 2008, due to a combination of low rainfall producing meagre river flows and ocean events creating a build-up of sand.

After rainfall in excess of 100mm late last week saw the lake level rise and some lakeside businesses flooded, Eurobodalla Shire Council excavated a channel from the lake to allow a rush of water to run out to sea about 1pm on Saturday.

The NSW National Parks and Wildlife Service hopes that also provides an escape route back to the sea for three dolphins who have been in Tuross Lake since August 2008, seemingly happily surviving in the lake's brackish water.

Eurobodalla Shire Council's director of roads and recreation Warren Sharpe said it was not clear if the dolphins had escaped over the weekend or not.

''There were quite a few rumours flying about the dolphins,'' he said. ''There were reports they went out on Saturday but I saw them in the lake on Sunday.''

For more on this story, see today's Canberra Times.