Sources and Pathways

Air
Chemicals from hundreds to thousands of miles away can travel as particulates in the air, eventually coming back down to earth. This type of atmospheric fallout may contribute to contaminants in the St. Joe, St. Maries and Coeur d'Alene river basins. These contaminants may then migrate through Lake Coeur d'Alene into the Spokane River.

Stormwater and Combined Sewer Overflows (CSOs)
The City of Spokane has over 700 miles of storm drains and sewer drains. Stormwater drains take urban runoff from rain and snow and discharges it into the ground and directly into the Spokane River. There are 130 storm drain outfalls into the river. Sewer drains carry wastewater from homes and businesses to a wastewater treatment plant. At times, primarily during large storm runoff events, wastewater that is not treated at the city's treatment plant discharges directly into the Spokane River from 27 combined sewer overflow outfalls.

Industry and Municipal Treatment
The Clean Water Act requires permits in order to discharge pollutants directly into the Spokane River. This is called the National Pollutant Discharge Elimination System (NPDES). The NPDES permits for the seven existing municipal and industrial dischargers are being reviewed as part of a renewal process. Although regulated and treated, some pollutants still enter the river. The proposed waste water treatment facility for Spokane County must also go through the NPDES permitting process.

Upstream
Heavy metals from one hundred years of mining in the Coeur d'Alene Basin travel downstream to the Spokane River. Flooding causes the most movement of metals downstream.