BOISE, Idaho — Boise city officials say the Ada County Landfill can't dump water that soaked through the region's trash into the Boise wastewater treatment system.

The Idaho Press reports the city turned down Ada County's request to dispose up to 4 million gallons of water collected from the landfill earlier this summer. The liquid, called leachate, was rejected because city officials say it could disrupt the water treatment process.

The last time the county dumped leachate into the water renewal system was 2010.

Lab testing showed the leachate ponds contained arsenic and nickel at rates 50 and 20 times higher than treated domestic water, along with small amounts of other organic compounds like phenol.

Ada County Landfill Director Kurt Hunt says he asked for permission to dump the leachate to be prepared in case of an emergency overflow of the leachate ponds, but there's not an immediate need to dispose of the water.