Moyog assemblyman Terrence Siambun claimed the landowners have breached the Stop Work Order imposed by the authority.
The tagal system entails zoning certain sections of the river, which would then remain off-limits to fishing activities for a certain period to allow the resources to flourish before being harvested jointly by the villagers involved.
Encroachers would be penalised with a fine under the Sabah Inland Fisheries and Aquaculture Enactment 2003.
Siambun urged the government, particularly Tourism, Culture and Environment Minister Datuk Seri Masidi Manjun to seriously look into the problems.
"It actually involves various ministries not only Masidi's. However, I am emphasising this issue more on to Masidi who had frequently voiced out his concern in protecting the environment but yet to take serious actions to work along with other ministries to save the Moyog River.
"The Moyog river debacle falls onto Masidi's ministry as the culture and environment are badly effected due to the pollution.
"Furthermore, tourism operators also complained that business had slowed as tourists refused to buy their products.
The muddy river had prevented tourists to enjoy the beauty of Moyog River since last year," told Siambun.
More than 600 Tagal Zones in nearly 200 rivers in 17 districts have been implemented statewide since 2000 costing millions of ringgit.
The Water Department had also voiced their concerns on the impact of the non-stop pollution in Moyog River.
The pollution due to hill cutting activities had disrupted water supplies not only in Penampang but also in Kota Kinabalu and Putatan.
Its deputy director Teo Chee Kong had said that the Kasigui Water Treatment Plant had to be shut down on many occasions as the Nephelometric Turbidity Units (NTU) readings were above the maximum 1,000 NTU set by the World Health Organisation (WHO) for a treatment plant to run efficiently.
"Penampang people are worried about the pollution. The city residents may not realise this but the pollution in Moyog River is alarming. Moyog River is the sole water source to all of us. Soon we are going to have a major water supply issue not due to the river not having enough water but caused by the murky water which actually can be controlled if the government of the day looks at this issue seriously.
"It kept me wondering, despite all the evidence, the landowners still carry out their activities.
Why is there no action taken against them? Are the owners immune from any legal actions?" he asked.
He also urged Masidi to be more responsible and sensitive when making statements on environmental impact in Penampang and go to the ground to look into the issue instead of simply assuming everything is still under control.
At the same time, Siambun asked the State government to fulfil its promises to utilise some of the RM390 million approved grants to solve the Moyog River problems.