The energy company uses 1500 billion litres of water annually for its Trevallyn Power Station, with just a fraction of that reserved for environmental flows into Cataract Gorge.

Professor Davis has proposed that increasing the water flow through Cataract Gorge would help flush silt from the estuary if combined with other restorative strategies.

``The trade-off is, that water is used for hydro-electricity, which we all desperately need,'' she said.

``So it's absolutely vital that (Hydro Tasmania) is prepared to look at ways in which more water may be delivered to the uppermost estuary while still maintaining their operations.''

The state-owned company has so far poured cold water on the idea of any more increases through Cataract Gorge.

Last month it increased the base environmental flow to 78 billion litres a year - about six times the flow it is obliged to release under its water licence, according to the company.

``That's our position,'' a company spokesman said yesterday.

``Siltation has occurred in the Tamar estuary for centuries and has been a significant problem for the Launceston community long before the Trevallyn Dam was built.''

Professor Davis said that the amount of water need to flush the silt may not even ``cut into power generation''.

One suggestion has been to reroute the power station's discharge back to Cataract Gorge and the yacht basin via a canal.

Hydro Tasmania said that this would mostly likely be highly expensive with ``no degree of certainty''.

Nevertheless Hydro Tasmania is involved in the process through the Tamar Estuary and Esk Rivers program, which it partly funds.

TEER is currently looking at Professor Davis's suggestions as part of a working group involving the Launceston CIty Council and other river stakeholders.

``The objectives of Professor Davis's proposal have to be very clear before we can determine what the best options to pursue are and what Hydro Tasmania will support.''