Bushfire damage combined with heavy rain falling on one of the shire's most important water catchments has forced local government to impose drinking water restrictions, while irrigation restrictions have been lifted.
With its forest catchment "denuded" by the Badja Forest and Werri Berri bushfires in January, the Brogo Dam rose from just 10 per cent to overflowing within 24 hours on Monday.
The catchment collected at least 5.6megalitres of water per minute, and 12 roads remained closed on Thursday, with the Bega, Brogo, Bemboka and Towamba Rivers and surrounding creeks posing a danger to the community, Bega Valley Shire Council said.
The combination of ash and debris saw council deem the dam water, which currently has no treatment plant, not suitable for consumption.
Council's water and sewer manager, Chris Best, announced Level 4 water restrictions for the north of the shire on Wednesday, and the trucking of a million litres of water from Bega to reservoirs, at a cost of $30,000 per day.
"The use of water outdoors for garden watering, washing cars and boats, or for any other purpose is not permitted," a council spokesperson said.
Mr Best said the "very expensive" measures would continue for now, with the cost of almost one million dollars per month likely to see it exchanged for a boil water notice at some point, with the turbidity level of the dam currently at well over 100 times the critical control level.
Water NSW, which controls Brogo Dam, lifted irrigation restrictions from the dam on the same day, one month on from being imposed on local farmers.
"In these circumstances, full water security has been restored, and the public interest reasons for applying the temporary water restriction, no longer apply," a Water NSW spokesperson said.
Mr Best said council had started planning for the approach in early-January, however trucks from as far as Albury have been called in to assist.
In 2018, Premier Gladys Berejiklian announced $25million for future water treatment plants for the Brogo/Bermagui and Bega/Tathra water supplies.
Mr Best said council was working closely with the Australian Defence Force to secure a portable water treatment plant for the supply, which residents are regularly forced to boil after heavy rain and floods.