RECENT rains in the SE have had a great ecological effect on the region, experts say.
With 43.6mm of rain falling in the area from August 19 to last Friday, Bool Lagoon is beginning to fill up for the first time this year.
Department of Environment, Water and Natural Resources district ranger for the Upper SE Brian Robins first noticed Mosquito Creek, which feeds into Hacks Lagoon and subsequently Bool Lagoon, flowing.
"I checked late last week and saw there was a flow in Mosquito Creek through Langkoop," Mr Robins said.
"On Sunday (August 19) water started flowing down the creek past Struan into Hacks Lagoon.
"Hacks Lagoon then overflowed and began filling into Bool Lagoon.
As of last Friday, Mr Robins estimates 700 megalitres has flowed into Hacks/Bool Lagoon.
He said the rains and the lagoon filling as a result was great for local fauna.
"It's very good ecologically - we're getting the breeding of birds for example," he noted.
"It supports a lot of invertebrates, insects and birds within the area.
He said there were 22 different species of wading birds currently enjoying the muddy conditions of the lagoon having a slight amount of water.
"There's quite a few wetland birds around at the moment, they're enjoying the mudflats."
"As the lagoon fills and the water gets closer and closer to the margin, more birds begin to arrive and breed from places as far away as Japan and China and even Siberia - up to 150 different species including 48 known breeders.
Black Swans and their young cygnets, Egrets, Ibis and Magpie Geese are now starting to populate the lagoon.
Mr Robins said anticipated spring rains would further enhance the breeding of the birds.
"It's going to help - lots of the breeding is done in Hacks Lagoon so as long as that remains filled up it'll be fine.
"With the increased bird population there comes an increased demand for food sources - also flourishing with the rains filling up the lagoon and providing them with suitable habitat.
The Southern Bell Frog is one of these food sources - surviving well despite being endangered elsewhere.
"They're certainly endangered in SA but there's quite a stronghold here in Bool Lagoon for them," Mr Robins said.
"We need to continue getting wet years to sustain their population."
He concedes the lagoon won't fill up to the extent it has done in recent years - resulting in the water needing to be let out - with only 10 per cent filled at this stage.
"It's fairly late at the moment - unless we get good continued spring rains it probably won't fill," Mr Robins estimated.
"I don't think it will fill at all - we won't need to let water out."