Fleet Pond-watchers claim that silt caught in Ministry of Defence silt-traps has ended up being pumped right back into the stream that leads to the pond.
Hart councillor Sharyn Wheale said she was horrified.
The pond is slowly silting up with soil washing down the Gelvert Stream from Army land at Long Valley. To stop the earth washing down, the Army built two traps, but these needed pumping out.
The silt was supposed to be pumped into an area around Long Valley, but Coun. Wheale says it was allowed to run out next to a tributary of the stream - with much of it running into the stream and then on into the pond.
"The MoD exasperate me," she said. "They know that stream. They've got to answer for this.
"Now we have more silt going in with an operation that should have created less silt."
Colin Grey, Chairman of Fleet Pond Society, said he felt very frustrated, but that efforts to rescue the pond had to carry on.
He said it is now possible to walk across from Sandy Bay to the large island in Wellington boots.
The MoD built the first silt trap in 1996 and a second was built higher up to catch soil that was washing down after two hills had their tops shaved off as part of a safety precaution for the airfield.
The pond society pressed the MoD to clean out both traps because they could not hold any more of the yellow sandy soil.
Mr Gray said they were assured the silt would be pumped on to open land, but much of it found its way to the pond.
Picture: Mr Gray at the Sandy Bay area of Fleet Pond, which is badly silted up now.