Developments need to back off of Wolf Creek, which runs through the heart of Grass Valley, to allow natural buffer zones to absorb runoff into the waterway.
That’s the conclusion of a volunteer water-quality watchdog group based on a decade of monitoring.
“Because it runs right through town, it does get affected from runoff from the streets. That’s a major issue for it,” said Jonathan Keehn, the president of the board of directors of Wolf Creek Community Alliance, which has coordinated a cadre of 15 to 20 volunteers who have tested the water quality at several dozen sites along the creek every month for the last 10 years.
The creek alliance’s compilation and analysis of that decade of data is the first study of its kind of the local watershed and was made possible by an approximately $9,000 grant, Keehn said.
The group will present an overview of their findings at a “State of the Creek” presentation today.
“It basically says the water is generally pretty good,” Keehn said. “There are no major problems with it.”
But the alliance wrote in its study that surrounding land uses have “greatly altered and impacted the creek, its riparian corridor and upland watersheds.”
Other threats beyond development pressure include current land use, irrigation, ranching, mining and climate change, the study notes.
The lack of sufficient natural habitats between Wolf Creek and developed areas is the biggest problem, Keehn said, and one that has led to an increased frequency of water quality decreases. Without such buffer zones to absorb and filter water runoff, rainwater often runs directly into the creek, carrying all the muck it accumulated while trickling down cement and other surfaces.
“You have to have a buffer zone on both sides of the creek to allow natural flow,” Keehn said. “With native plants and as much soil with plants growing on it as possible, the wider the buffer is and the safer your creek will be. It’s that simple.”
Wolf Creek, a tributary of the Bear River, is a perennial stream whose watershed encompasses roughly 80 square miles and includes 18 subwatersheds. Its main stem is approximately 23 miles long. Wolf Creek’s headwaters begin at the south side of Banner Mountain, located just east of Grass Valley, and flow south to join Bear River at the Placer and Nevada counties’ shared border. Most of the area traversed by the creek outside of Grass Valley is agricultural and rural-residential land situated in mixed conifer forests and blue oak woodland habitats.
The nonprofit environmental group also found that temperatures of the water are higher than they should be at certain points along the creek, Keehn said.
“Right below the (Grass Valley water) treatment plant, waters are higher in temperatures than it would be if it were a natural flow,” Keehn said, citing one example. “That can be an issue for fish.”
Grass Valley’s water treatment plant has impacted the creek in other ways, too. The treatment plant has exceeded its intake capacity and overflowed into the creek at least three times in the last five years, according to the state Water Resources Control Board.
“(Water quality) occasionally gets affected negatively whenever the wastewater treatment plant gets overloaded,” Keehn said.
While Grass Valley has incurred fines for those instances, the city has blamed Empire Mine, which accounts for nearly a quarter of the plant’s incoming untreated water, as a contributing factor to its overflows.
In a February 2009 settlement agreement with the city, Empire Mine’s owner (the Newmont Mine Corporation) agreed to construct its own treatment plant to keep water from flowing into the city’s system. However, Newmont missed a May deadline to begin building the plant.
“Enough is enough. We need to get to the state and say, it’s time,” said Jeffrey Foltz, Grass Valley’s interim city manager, in a Wednesday interview with The Union. In that conversation, Foltz rounded his fingers into the shape of a zero to describe how much Newmont Mine has done toward building a water treatment plant.
“For the health of the city going forward, that issue needs to be solved and put to bed and get Newmont’s water out of the city sewer plant,” Foltz said.
The Wolf Creek Community Alliance members hopes their study will raise awareness of the creek’s challenges and influence future decisions that could further impact the waterway, Keehn said.
“We feel that … 10 years of doing the same type of monitoring and being able to consolidate the info in one spot is a very satisfying feeling,” Keehn said. “We are glad to have done it and to be able to share it.”
To contact Staff Writer Christopher Rosacker, email firstname.lastname@example.org or call 530-477-4236.