The dredging program is idle and the level of silt build-up is causing concern among residents and businesses.

The state government, which promised millions of dollars for dredging in 2010, said it no longer believed the practice was a solution.

However, the Launceston City Council is looking to conduct limited dredging and raking.

Council general manager Robert Dobrzynski said the council believed that raking at the right time and dredging would reduce visible silt below the low-water mark. He said it would offer a short-term solution until a permanent one was found.

Bass Labor MHR Geoff Lyons said on Sunday he would not seek funding until a longer term strategy was found, prompting the opposition to pledge $2.5 million in emergency dredging.

Senator Stephen Parry and Bass Liberal candidate Andrew Nikolic announced the pledge yesterday.

The ponds that collect silt from the Tamar when it is dredged have the capacity for another 70,000 cubic metres, but any large-scale dredging would require them to be emptied. Tests have indicated that the ponds contain significant amounts of acid sulfate, limiting disposal options.

Trials are being conducted on the silt to help determine the best way to dispose of the contaminated waste.