Armed with six high school students, hardly any money and more than 100 clams, Harriette Phelps is on a crusade to find pollutants that are plaguing the region's waterways.

It's simple. Collect clams from the Potomac River. Move them to another creek or stream for two weeks so the tissue absorbs everything in the water. Take them out. Freeze them to death in Phelps's refrigerator. Send the tissue to a lab. Yell like hell to local officials when pollutants turn up.

Unfortunately, county and state officials don't always listen, Phelps said. But after her latest study found levels of a banned termite poison two to four times the acceptable level for wildlife in certain areas of Sligo Creek in Wheaton and Silver Spring, Phelps is lobbying those same state and county officials to help her find the contaminated source.

"Nobody is interested in funding this kind of stuff," Phelps, a retired biology professor at the University of the District of Columbia, said in the living room of her cluttered Greenbelt home earlier this month. "If it's not killing people nobody seems to care, which is understandable.

"It's not a public health issue but it's an environmental issue."

In the case of Sligo Creek, Phelps wants to make that last point clear. While the termite poison, called chlordane, has been banned in the United States since 1988, it cannot harm humans unless they drink the water in Sligo Creek—not recommended—or eat the fish—prohibited.

It's the "environmental issue" that Phelps is talking about to anyone who will listen.

The maximum level for chlordane for protection of wildlife is 100 parts per billion, according to the National Academy of Science/National Academy of Engineering. Phelps found levels of 240 ppb in the lower portion of the creek in Takoma Park and the highest level, 480 ppb, in Sligo Creek's main branch, near the Kemp Mill neighborhood of Silver Spring.

"We did not expect to see what we are finding, there are a few places where it's concentrated," said Phelps, who has been conducting clam studies for more than 10 years and examined Sligo Creek in late 2008 and 2009 thanks to $4,000 in funds raised by Roosevelt.

While it's no threat to humans it is a threat to fish and anything that eats fish, Phelps said. But even the level of that threat is being questioned by county and state officials.

"We aren't sure about her results, but even if they are accurate, the main concern would be if the people were eating fish," said Steve Shofar, a division chief for watershed management with the Montgomery County Department of Environmental Protection, in a phone interview.

As part of its restoration project in Sligo Creek, DEP reintroduced about a dozen new fish species into the creek between 1983 and 2007, said Keith Van Ness, a senior water quality specialist with DEP. And through its countywide bio-monitoring program, DEP has found the fish species in Sligo Creek have remained mostly the same, Shofar said.

Although DEP doesn't conduct toxic monitoring of its waterways—that's the state's job—"if there was a chlordane problem we think we would be able to detect that," Shofar said, because chlordane affects the reproductive ability of fish.

"We're not seeing problems with the fish," he said.

Friends of Sligo Creek, a local citizens group dedicated to improving the quality of the Sligo Creek Watershed, conducts its own tests of the creek's water quality and works with the county DEP to report any contamination, including in 2006 when a FOSC report lead to Washington Adventist Hospital being fined for illegal dumping.

"FOSC considers Sligo Creek to be in poor condition," admitted Mike Smith, chair of FOSC's water quality committee. "We don't represent it to be in clean condition."

Phelps believes the solution is finding the source of chlordane, which could date back to 1988 when one or multiple chlordane users may have scrambled to dump their supply after the substance was banned. Over time, the chlordane may have seeped into the watershed soil and creek beds, Phelps said. Given the high levels in the main branch near Kemp Mill and the diluted levels downstream, Phelps believes the source could be in the northern part of the main branch, near University Boulevard and Arcola Avenue.

In any case, the Maryland Department of the Environment would assist in finding the chlordane source, which they are open to doing, said Jay Apperson, an agency spokesman. But MDE, too, wants to see if Phelps's findings are accurate.

In 2007, MDE conducted its own clam studies in the Anacostia Watershed, including Sligo Creek, and did not find excessive levels, Apperson said. MDE will meet with Phelps to determine any discrepancies in testing methods, Apperson said.

"We get a lot of information and we take it all seriously," he said.

Phelps said MDE has been inconsistent in responding to her past findings, which include contaminants in Indian Creek in Beltsville, Still Creek in Greenbelt and Lower Beaverdam Creek, which winds throughout Prince George's County. Regardless of what happens at Sligo Creek, state officials, including Montgomery County Executive Isiah Leggett and Gov. Martin O'Malley, unveiled a $2.7 billion plan on April 19 to restore the heavily polluted Anacostia Watershed, which leads into the Potomac River and Chesapeake Bay.

State officials said they are seeking $60 million for projects in the next federal budget but there's no indication how that will affect Sligo Creek.

In the meantime, Phelps will do what she always does, sticking by her clams and her longstanding belief that the people with environmental power don't know everything.

"Healthy is a matter of definition, maybe the creek is missing some species they don't know about," she said. "It's not like all of a sudden everything's dead."