Impact to ecological reserve is top concern for Temecula quarry opponents

Another big crowd will pack the Rancho Community Church in Temecula Monday morning for another long hearing on the proposed Liberty Quarry. The quarry could be a significant source of jobs and tax revenue for Riverside County, but there are environmental risks.

The question for the county planning commission is whether those risks can be reduced, or eliminated. Biologists that work at a nearby ecological reserve don’t think so.

San Diego State University biologist Matt Rahn stands on a windswept bluff overlooking the Santa Margarita River, Southern California’s last freeflowing river from the mountains to the ocean. Surrounding it is a 4,600-acre ecological reserve that’s also the last inland-to-the-coast corridor for migrating wildlife.

“As Southern California grew up around us, we sort of became the last in a lot of things," Rahn says. "And that’s part of what draws a lot of researchers to this property. Because it’s this sort of window into the past. We have a lot of researchers come here to use it as reference site for what natural conditions in Southern California should look like."

Rahn directs the Santa Margarita Reserve field station – a living laboratory for climate change research, ozone monitoring, seismic study and more. He says it’s a bad idea to carve a 135-acre, 1,000-foot deep open-pit mine within a few hundred feet of the reserve.

Liberty Quarry would use explosives to blast rock loose for cement and asphalt. Processing plants would run 20 hours a day.

“In a lot of respects, you really couldn’t really have picked a worse place environmentally," he says. "We’re concerned across all the major environmental issues, seismic issues, the noise, the lighting, removal of groundwater from the mountain, of course, the wildlife movement corridor. So it’s just another additional loss on a region that’s already lost so much.”

At Granite Construction’s Rosemary Mountain quarry in San Diego County, project manager Gary Johnson touts the benefits of a new quarry: a steady supply of building material to a growing region, dozens of good-paying jobs and millions in annual tax revenue. Johnson says the quarry and the Santa Margarita Reserve can coexist.

“We designed the project to limit impact so they’re not significant," says Johnson. "The county has reduced the hours we can mine, reduced the hours of operation, added a lot of buffer around the site and we’ll be doing air monitoring and vibration monitoring to make sure there’s no impact.”

Johnson says Granite Construction supports the reserve’s mission. He’s toured the area and met with biologist Matt Rahn and other San Diego State representatives.

“There’s actually a number of researchers from the reserve who have sent letters to the county saying not only would we not impact their research, but they see us putting the quarry where it is as additional research opportunity for them,” Johnson says.

But when asked, the company couldn’t say who sent letters in support of the quarry. San Diego State’s Matt Rahn says they weren’t researchers, but private contractors the university hired to install monitoring gear at the reserve field station. He says they aren’t doing scientific research.

“One of them had actually provided us with equipment for a research project on wildfire sensors,” Rahn says. But Granite Construction has welcomed San Diego State scientists to conduct research at the proposed quarry site.

San Diego State earth scientist Gary Girty does field research at the Santa Margarita Reserve. He’s looking at how earthquake energy affects rock structure. He says the quarry could be a valuable resource for seismic research. He used research from one of the sites in a recent research paper.

“They’re gonna dig a deep hole, and if you can follow the hole down, characterize what’s going on with the rocks as you get deeper and deeper, it might give you some really neat clues as to what goes during rupturing events along the Elsinore fault," says Girty.

Girty says he understands why people living near the proposed quarry, and colleagues like biologist Matt Rahn, have concerns. But in a battle where emotions run high, Girty says both sides have good points.

“And somehow or another, there must be some mid-range here that can satisfy all these different views, and I just don’t know what that is,” Girty says.

That’s for Riverside County Planning commissioners to figure out. As they have at other marathon hearings, they’ll listen Monday as Liberty Quarry officials and their advocates make their case. If commissioners OK the project, it moves to the Riverside County Board for final approval.