The past president of the community environment group said the threat to the water supply could have far-reaching implications.
The State Administrative Tribunal (SAT) in April overruled objections by residents and the Shire of York to the revised landfill proposal for Allawuna Farm by waste giant SITA Australia.
�As residents who source water from this catchment, we have the right to protect these natural drinking resources from any impending threat of contamination and pollution from a large, putrescible waste facility,� Mr Cable said.
�Water along this creek line during the summer periods is fresh and drinkable and, having surveyed this creek line, we have observed fresh water ponds that leach drinkable water out of rock formations in the centre of this system.�
Opposition to the landfill proposal resurfaced again in April after the SAT ruling.
Mr Cable said he had a sound knowledge of the catchment area, having conducted water-sampling tests and field studies of the upper reaches over 16 years of working alongside land management volunteers.
�This is still a viable catchment where the water is unpolluted and needs protection from further salinisation and pollutants . . . the very reason large amounts of government monies and volunteer labour have gone into the protection and plantation of large amounts of native seedlings in the upper reaches of this catchment,� Mr Cable said.
The planting of more than 300,000 native seedling stems in the upper catchment attracted government funding.
�How illogical is the placement of a huge, putrescible landfill adjacent to a creek line that has a large paleo-channel and aquifer, depositing fresh water into the Mundaring, Helena drinking water catchment?� Mr Cable said.
�Living in one of the driest continents on planet Earth, our precious natural drinking resources should be protected at all costs.�
Mr Cable said with the prediction of continuing depleted rainfall, there should be no negotiation on placing a large landfill in a drinking water catchment.
SITA Australia state general manager Nial Stock said the Allawuna Farm project was a well-planned facility that met environmental standards and would deliver economic benefits to the York region.
�All water sources will be protected and separated from the landfill,� Mr Stock said.
�The Department of Water has confirmed the landfill will not impact on the Mundaring Weir drinking water catchment.�
The reassurance on water by SITA follows previous residents� concerns about the number of road trains transporting waste through Midland, Glen Forrest, Mundaring and Sawyers Valley to the proposed landfill site.
Mr Stock said a maximum of eight pocket road trains � each doing three round trips a day and setting off at about 35-minute intervals � would transport waste to the site.
Public submissions closed last month and are under review by the Department of Environment Regulation.
The Wheatbelt Joint Development Assessment Panel is due to reconsider the Allawuna Farm proposal before July 15.