Almost 300,000 students from metro Denver school systems will be barred from school-sanctioned trips to Rocky Flats National Wildlife Refuge after it opens this summer, with the state’s largest district enacting a ban last week on visits to the former nuclear weapons manufacturing site.

Denver Public Schools joined half a dozen other local school districts that say Rocky Flats, with its legacy of plutonium contamination that was often shrouded in secrecy, is too much of a risk for visiting schoolchildren.

“We live in the state of Colorado, where there are plenty of opportunities to enjoy the outdoors,” said Lisa Flores, a member of DPS’s school board, which Thursday brought forward a resolution forbidding its nearly 100,000 students from taking field trips to the 6,200-acre site, which sits 16 miles northwest of Denver. “This is a site we can take off that list.”

Boulder Valley School District and St. Vrain Valley School District passed similar resolutions last year, while superintendents at Adams 12 Five Star, Adams 14, Westminster Public Schools and Jefferson County Public Schools have issued directives forbidding field trips to Rocky Flats. The refuge is scheduled to open to the public this summer, although no firm date has been announced.

Christopher Allred, a member of the Rocky Mountain Peace and Justice Center and who has led the effort to get school districts to sign on to the ban, said the unanimous vote by the DPS board is a “very clear statement on the public’s concern about this issue.”

In the middle of the refuge is the 1,300-acre Central Operable Unit, where the sprawling weapons plant that formally closed in 1992 was actually located. It remains an off-limits Superfund site, a bleak reminder of the toxic history surrounding the former federal facility, where for nearly 40 years triggers for nuclear bombs were assembled.

“This is really about the urgent public health issue around the U.S. Fish and Wildlife Service opening up Rocky Flats (for public use),” Allred said. “The fact that the refuge is surrounding an active Superfund site means we need to be cautious.”

But Carl Spreng, the Rocky Flats program manager with the Colorado Department of Public Health and Environment, said there is nothing clear — or accurate — about the information school districts are getting from what he characterizes as a “traveling activist group” dead set against seeing the refuge open.

“At the core of this is anti-nuclear sentiment,” Spreng said. “They’re using scare tactics.”

He doesn’t deny the environmental problems that have been caused by Rocky Flats, which saw two plutonium-releasing fires in the 1950s and 1960s and an infamous storage pad where barrels leaked a noxious stew of plutonium-laced oil and solvents into the ground. But he said a decade-long cleanup, completed in 2005, was a success.

The rolling property between Arvada and Superior, he said, has been exhaustively tested for contamination over the years — with hundreds of thousands of surface and subsurface soil samples taken — with no areas inside the refuge’s boundaries found to have plutonium readings above what the state considers a health risk.

Radiation levels at Rocky Flats, Spreng said, are in line with background levels found in other parts of the state. According to the CDPHE, the average Coloradan is exposed to up to 650 millirems of radiation a year — a dosage that falls somewhere between a mammogram and a CT scan. A year’s worth of Rocky Flats radiation would add less than an additional millirem to that exposure level, Spreng said.

He said the losers in the effort to ban field trips to Rocky Flats are the kids, who won’t get to enjoy the sight of deer, elk, coyotes, prairie falcons and songbirds traversing the tallgrass prairie in their natural habitat.

“School districts have denied their students the opportunity to see an urban wildlife refuge,” Spreng said. “I’m frustrated by that.”

Worse still, he said, is that several of the school districts never contacted his office or the U.S. Fish and Wildlife Service to get the other side of the story before prohibiting school visits.

“The districts are making their decisions in the absence of full information,” Spreng said.

DPS’s Flores acknowledged that the district should have spoken with state health and federal officials before accepting the Rocky Flats opponents’ argument on its face. Not that the outcome of last week’s vote would have been any different, she said.

“In retrospect, yes, it would have been good to hear from these entities,” she said. “But the fact that it was a nuclear Superfund site had the larger bearing on the issue.”