Idaho cities will be required to cut their phosphorus discharges into the Spokane River by more than 90 percent over the next decade to protect water quality.
The new limits are included in wastewater discharge permits for the cities of Coeur d’Alene and Post Falls and the Hayden Area Regional Sewer Board, which were issued last week by the U.S. Environmental Protect Agency.
“I’m still digesting it,” Sid Frederickson, Coeur d’Alene’s wastewater superintendent, said of the 50-page permit. “But as near as I can glean, there were no surprises.”
The new permits come after years of effort to reduce algae blooms and boost dissolved oxygen levels in the river. Washington dischargers have been operating under similar limits since 2011.
The permits require some of the nation’s lowest phosphorus emissions in treated sewage. By December, 2024, the city of Coeur d’Alene’s treatment plant will be limited to just over three pounds of phosphorus in daily wastewater discharges.
The ratio is 50 parts per billion of phosphorus in the discharges, said Brian Nickel, an EPA permit writer. That’s the equivalent of a single drop of water in an olympic-sized swimming pool.
Coeur d’Alene, Post Falls and the Hayden sewer board are already working on improving their systems and installing new technology to achieve the new limits.
Coeur d’Alene is anticipating $33.5 million in improvements to its wastewater treatment plant over the next decade. The Hayden sewer board broke ground this summer on the first phase of a $31 million project to reduce phosphorus in its wastewater. Post Falls expects to spend roughly $60 million on its treatment facility over the next two decades, said John Beacham, Post Falls’ environmental manager. That work includes improving the plant’s efficiency, better phosphorus removal and other upgrades to keep the plant in compliance with operating permits, he said.
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