The Spokane River Watershed – Contemporary Issues and Ongoing Solutions
March 2, 2016
This is the second in a series of four articles about watershed planning efforts in Spokane County, and the vitally important role conservation plays in protecting our diverse watersheds.
The Spokane River watershed contains the most diverse mix of landscapes and land-use in the region. The watershed extends from the headwaters located high in the temperate forests of north Idaho, through the urbanized corridor connecting Coeur d’Alene to Spokane, and ultimately on to the river’s terminus on the arid Columbia plateau.
The watershed includes abundant natural resources including forests for timber harvest, mineral-rich geologic zones for mining, and fertile agricultural areas. It also includes one of the most prolific, yet vulnerable, ground water aquifers in the western United States, the Spokane Valley – Rathdrum Prairie (SVRP) aquifer that supplies drinking water to over a half million residents. The regional economy depends on these natural resources and industries, but there has been a cost in terms of water quality and quantity. Conservation planning can help to mitigate some of these impacts.
Water quality impacts from urban development are significant and the costs are high. Sources of municipal pollution primarily include stormwater, industrial facilities, and municipal wastewater treatment plants. Local conservation efforts have played a role in addressing some of these sources.
Regional stormwater managers have begun to embrace the idea of using natural drainage for transporting and treating stormwater. Why fight Mother Nature? Local examples include the Hazel’s Creek and Browns Mountain projects in south Spokane and the Price/Wall facility in north Spokane.
Another example is disposal of reclaimed municipal wastewater. Increasingly, municipal wastewater treatment facilities are discharging reclaimed water into wetland areas, protecting surface water resources while also recharging aquifers and developing wildlife habitat. The City of Cheney’s facility near Turnbull National Wildlife Refuge is a local example. Another example is Spokane County’s efforts in the Saltese Flats area, which is used for agriculture and grazing, and was identified in the Spokane River watershed plan as a prime area to conserve for wetland restoration. Spokane County purchased 510 acres from willing parties and now a design is underway to restore the wetland functions. The restored area will slow water runoff to recharge the aquifer and benefit late summer flows in the Spokane River, restore habitat, provide recreation and education opportunities, and could potentially be used for application of reclaimed water.
Water quantity impacts in the watershed are well documented, but are more difficult to address. Flow records for the Spokane River extend back to the early 1900s, and late summer river flows in the Spokane River have diminished significantly over the past 100 years. Low river flows late in the summer affect habitat, particularly for fish. The history of water use of the Spokane River and the SVRP aquifer is complex, and has changed over the years as the Spokane Valley converted from primarily agriculture to residential use. Other factors that can influence river flows include climate, municipal water use (particularly in the late summer), and forest management practices.
Timber harvesting and development of rural forested areas can reduce protective tree canopies that shelter snow cover. When canopies are removed, the snow melts more quickly, accelerating spring runoff which results in flooding and lower late-summer stream flows. Conserving forested lands can help to maintain snow cover later into the spring, and INLC has helped many landowners conserve their forested properties, preserving trees as protective canopies and reducing premature runoff.
Finally, this is where your stewardship comes in…you too can have an effect on the local watershed and the Spokane River by simply conserving water. It’s well known that the SVRP aquifer and the Spokane River are hydraulically connected. Studies by the United States Geological Survey (USGS) indicate that up to 50% of the water in the aquifer comes from the Spokane River, specifically the section between Post Falls and Sullivan Road in the Spokane Valley. Downstream from Sullivan Road the aquifer recharges the river with cool water. If you fish the Spokane River you know where the cool water is! Because of this connection between the aquifer and river, some of the water removed from the aquifer for summer lawn watering could have been recharging the river. So, if we all conserve just a fraction of the water we use in the summer, the beneficial effects would be seen as a healthier river. Think about it!
Please contact me at rlindsay@spokanecounty.org if you have any comments or questions. I look forward to hearing from you. See you in the next issue!