Previously stripped bare of vegetation and ravaged by gully erosion, "The Gib" now has a green ribbon along Turallo Creek from leaky weirs which slow the water flow and trap sediment after storms and floods. Mrs Davy hears masses of noisy frogs whenever she walks down to a weir in the quiet of sunset.

But the NSW Office of Water's threat of a $1 million fine hangs over the Bungendore property, and another $132,000 for every day it fails to pull out the concrete barriers that form the weirs, which have been a labour of love for Mrs Davy and her late husband, Bill, who died in 2010.

Mr Davy was sceptical when the couple visited Mulloon Creek, east of Bungendore, to discover sequence farming, a concept developed by controversial farmer Peter Andrews for reducing drought severity and boosting farm and landscape productivity.

Part of the Canturf owners family who have been farming in the district for more than eight generations, Mr and Mrs Davy brought "The Gib" in 1982, and began repairing barren and degraded land. They hauled concrete blocks into the creek, and encouraged reeds and grasses to take hold, and insects, larvae, snakes, yabbies and water snails to come back.

The aim is to reintroduce a natural valley flow pattern to reconnect the stream to the flood plain, and water rats, and cattle egrets feeding in the reeds are sure signs life is returning.

The Office of Water's controlled activity notice, issued in September last year, refers to 24 water managed works and seven piles of excess concrete material. Unmoved, the Davy family is holding an open day on Saturday to demonstrate sequence farming, and Mrs Davy hopes a frog expert will be among the visitors, to reinforce the value of their stream remediation.

"I'm pissed off," Mrs Davy said. "I'm annoyed with what the government is doing. " She said the expense of undoing all the work is the least of her worries. "Mentally it would be disastrous, I love the creek, it is beautiful, it's changed so much from a dry creek bed to green grass, the cattle love it."

Turallo Creek runs downstream through several smaller properties; Bungendore village; a large property, "Turallo", owned by the Davy family; and ultimately into Lake George. Mrs Davy believes more water leaves "The Gib" now than it did before the recycled concrete and naturally forming land bridges appeared.

"Water seems to attract water. I am no scientist, but I am passionate about this. The government is yet to get with it [national sequence farming]. You only have to drive to Cooma and you see dry gullies everywhere," she said.

Mrs Davy's daughter, Kate, said they had made submissions to the NSW government, and had opinions from a scientist and hydrologist who said dismantling the leaky weirs along the creek would be more devastating for the stream, but did not know where they stood with the government agency.

The Office of Water said in a statement that it was continuing to liaise with the Davys regarding unauthorised structures in Turallo Creek, had engaged an independent expert to report on the structures and the implications of either leaving them in place or removing them.

This would be done before reaching the most suitable outcome for the property owners, downstream landholders and the environment.