A 2016 report to the council said the capital's development boom had meant a large volume of clean fill was being taken from Canberra and dumped across the border in NSW.

The report identified four hotspots where large volumes had been dumped, all close to the border: Wallaroo just across the border from Gungahlin, Tallagandra Lane, the Nanima Road and Spring Range Road area, and the Kaveneys Road and Dog Trap Road area. The latter is currently the site of five approved dump sites.

In just over a year to May 2016, the Yass council received 61 reports about the dumping, along with "numerous others" that related to matters already on file.

"Each site of an incident has often involved multiple site inspections to gather information or monitor activities for compliance," the report said.

Since May 2016, the report's two big recommendations have been met: an ACT certification system for the clean fill leaving Canberra and lowering the minimum allowed to be dumped without a developer's application.

The report said at the time ACT agencies had stopped contaminated fill being transported to NSW, according to the report.

It also said the excessive clean fill would lead to problems with the water quality of Yass's drinking water catchments as loose topsoil made its way into water supply areas.

In a more recent report to council on a development application, Canberra construction companies were said to be avoiding the high cost of clean fill disposal in the ACT by dumping thousands of tonnes of fill just over the border in NSW.

A recent development approved by council in December would have 90,000 tonnes of clean fill dumped on a NSW farm. It would have cost more than $1 million to be dumped in Canberra landfill.

Instead the company responsible will be required to pay the council $2110 as a contribution towards maintaining Kaveneys Road, where the farm is located, due to the increased truck movements.

The 2016 report said the amount of trucks from Canberra laden with clean fill was having a detrimental impact on the council's roads.

Even then, residents were complaining of the dangerous driving of the truck drivers, the dust raised from the constant truck movements, the deteriorating roads and the noise caused by the constant presence of heavy vehicles.

"It is considered that the occurrence of filling and these issues will be exacerbated with population increase and development in ... both Canberra and the locality," the report said.

Council planning director Chris Berry said developers were charged a proportional rate by council for the number of trucks they were bringing on to the road.

"You can't push the total maintenance cost across to the new developers," Mr Berry said.

He said the council didn't receive any other financial compensation out of the dumping.

"We don't get anything out of this because these are private interests," he said.

The 2016 report said the exported material from Canberra had the risk of infesting NSW local government areas with weeds.

"A number of areas in the ACT have high incidents of serrated tussock and other weeds which can easily be introduced to Yass Valley areas with the movement of the fill," the report said.

The ACT and Region Catchment Management Coordination Group, a multi-government water management group, expressed concern in the report citing the impacts clean fill dumping would have on water quality for the region's catchments.

Just recently over the Christmas period a failure at the treatment facility saw Yass's drinking water turn brown.

Mr Berry said this was an aesthetic problem and while topsoil runoff from dump sites could impact the region's water supply, the blame was mainly on Yass's geography and the drought conditions gripping the state.

The report made two recommendations, which have been followed by the NSW and ACT governments.

Mr Berry said suggestions to introduce a certification system for the clean fill had been met by the ACT government.

These certificates guaranteed it was free from contaminants and weeds while identifying where it was from and where it was bound.

However, The Canberra Times previously reported this self-certification process was still seeing fill contaminated by plastics and steel being dumped across the border.

Mr Berry said a certificate was requested by council workers if they had serious doubts after performing an initial visual inspection of the fill being dumped.

The other suggestion saw the NSW state government change the minimum amount of clean fill allowed to be disposed of on a property.

Previously developers were allowed to dump 600 millimetres of clean fill without approval, but in a loophole, there was no limit on volume nor the area of fill, other than the property's size.

"An area of 10 [hectares] with 600 [millimetres] of filling equals approximately 60,000 cubic metres of material or approximately 6500 truck loads," the report said.

The council now requires development applications be lodged for any dumping over 100 cubic metres in size.

An ACT government spokeswoman said there was no risk to Canberra's water supply from the clean fill dumping in Yass.