For some, a relaxing afternoon on the river and the chance for free meals outweigh the risks of cancer.
Walter Cool of Lawrence sat at water's edge with his two limp fishing lines extended loosely before him, one baited with a worm, one with chunks of fish.
At his feet: a plastic container full of shrimp held in reserve as backup bait.
Buckets, tackle boxes, beer bottles and a dozen other fisherfolk were scattered across the flat slabs of rock beneath and just to the north of Bowersock Dam on the Kansas River.
The scent of fishing apparatus and fish guts mixed with cigarette smoke.
The river gushed through the dam spillway. Above the dam, cars and trucks rolled in a steady urban stream across the bridge that connects downtown Lawrence with North Lawrence.
It was a fine, hot April afternoon. Some anglers used liver as bait. Some had luck, some didn't; among them, Mr. Cool.
Perhaps, though, he was better off fishless.
In December the Kansas departments of Health and Environment and Wildlife and Parks warned that bottom-feeding fish caught in the Kansas River anywhere below Bowersock Dam in Lawrence have concentrations of a chemical called chlordane in their fat that makes consumption of more than 5 oz. a month, or 60 oz. a year, a risky affair.
Until 1988, when the U.S. Environmental Protection Agency banned chlordane, the chemical was commonly used in urban areas to kill termites. It was banned because of a suspected direct threat to humans, not because of accumulation in fish tissue, said Steve Cringan, an environmental scientist with KDHE in Topeka.
But even after it was banned, chlordane continued to make its way from the cities and towns where it had been used into the nation's rivers, where it was consumed by and accumulated in fish.
The further downstream the fish, the higher the concentration of chlordane, Cringan said.
"Chlordane and some other pesticides can be accumulated to really tremendous levels compared to what you see in their surroundings," Cringan said. "One might be better off fishing upstream of town rather than downstream."
He noted that the EPA banned several similar pesticides, such as DDT, in the early 1970s, but that even 20 years later traces of the pesticides were still found in fish.
"And to my knowledge they were never seen in fish tissue to the levels we're seeing chlordane," Cringan said. "So that leads me to believe we'll be seeing chlordane in fish for many decades."
Chlordane is classed as a probable human carcinogen -- "a fairly potent one," Cringan said. Cringan said in particularly high concentrations chlordane also can cause liver damage.
The taboo bottom-feeding species in the Kansas River include carp, blue catfish, channel catfish, flathead catfish, freshwater drum, bullhead, sturgeon, buffalo, carpsucker and other sucker species.
Such fish caught within 18 miles of the river's confluence with the Missouri River in Kansas City, Kan., should not be eaten at all, according to KDHE.
Like others fishing the river, Mr. Cool knew about the government warnings of dangerous chemicals in the fish. And the warnings made no difference to him. He wanted to catch something. He said he spent much of the previous summer fishing the river.
Jerry Rice of Wellsville had a similarly unproductive afternoon. After three hours of fishing and nothing to show for it he was ready to pack up and head home.
It was, he said, his first time fishing the river since the 1950s. He said he usually fishes in area lakes, which the KDHE said "do not appear to have bottom feeding or bottom dwelling fish with significant chlordane contamination."
Rice also knew about the chemical contamination in the Kansas River fish.
"That's why I don't fish in rivers much," he said.
In any event, he doesn't eat fish. If he does catch anything, in a river or a lake, he said he brings it home to his mother, who is 75 years old.
Alicia Fletcher had, by fishing standards, a better day. She had gone out to the river with her mother for some "quality time."
"We don't get much time together," said Fletcher, a 23-year-old Lawrence nanny and Kansas University student.
Of course they didn't forget their fishing poles, and they continued fishing despite the health risk. The day before Fletcher had caught three fish in the river.
"When I bring fish home it's a big deal," she said. "It's a free meal."
With her mother she caught a four-pound carp. Later a "big one" snapped her line. No matter. She already had plenty of fish for her roommates -- and probably a decent load of chlordane for them as well.