"The main reason for declining storage is lack of rainfall/inflows into the dam due to dry conditions,'' he said.

"This is combined with water being delivered to water customers with a legal entitlement to water, downstream communities, environmental licence holders (ie state and federal governments), as well as the riverine environment under the terms of the valley's water-sharing plan,'' Tony Webber explained.

"Whole allocations are restricted as availability drops, dam levels will only rise with significant rainfall, sufficient to saturate the catchment.''

There is no threat of water restrictions in the region it's understood.

"As a provider of untreated bulk water, State Water Corporation does not play a role in water restrictions or any other aspects of urban water provision,'' Mr Webber said.