Gender-bending fish found in Colorado rivers
EAGLE – When veteran fish biologist John Woodling decided to examine fish inhabiting waters below Front Range sewage plant outlets, what he found shook him and attracted national media attention.There were very few males and the reproductive organs of both male and female fish had hermaphrodite tendencies: They contained both male and female tissues. It’s a scenario he fears may have long-term implications for humans, including people in Eagle County.Woodling, 58, believes the changes in these inter-sex fish were caused by a cocktail of pharmaceutical substances – such as antibiotics, hormones, steroids – that humans use and pass along to the environment. Those substances could lead to extinction of some species because they may interfere with reproduction, he said. “This is the first thing that ever freaked me out,” Woodling said Wednesday during Waterwise Wednesday, a monthly presentation of the Eagle River Watershed Council, an environmental group. “The ratio of males to females is so totally skewed, it’s not funny.”Woodling’s research was conducted on white suckers, a fish common to the rivers in Boulder, Denver and Colorado Springs.We are what we drinkBecause Colorado is a water-poor and people-rich state, what’s happening to the fish could happen to humans, he said.It works like this. As the state’s demand for water increases, it will require humans to recycle the water they use, exposing humans to hundreds of recycled pharmaceuticals.And that’s not a future-based scenario. Many Front Range cities have water systems that depend on reused water.Woodling suspects the substance behind the sexual mutations in the fish was nonylphenyls, a common substance found in many plastic containers that can transfer to the food and beverages they hold.”Nonylphenyls are bad,” he said, noting that some European countries have banned their use. “They’ve been found in everything we eat.”Those, and other substances called endocrine disrupter chemicals, are in broad use by humans. When ingested or when organisms are exposed to them, they can cause harm. That exposure in concentrations as minute as a just a few parts per-billion can be harmful over the long term, Woodling said. Wastewater treatment plants, at present, do not remove many of the endocrine interrupters that can cause changes in living organisms, said Bob Trueblood of the Eagle River Water and Sanitation District, which operates local wastewater treatment plants. Endocrines are glands that secrete hormones in living organisms that stimulate development or regulate bodily processes. But local water systems do not rely solely on recycled water, so sources of raw water are less contaminated than recycled water is, he said.The Vail sewer plant does release treated water into Gore Creek, which flows into the Eagle River, which is used as a raw water source for the Avon water treatment plant. But the percentage of treated to untreated water in the river here is far less than it is in Front Range rivers where treated water can comprise up to 98 percent of the flow.”Dilution is the critical factor,” Trueblood said.Trueblood said the district regularly tests water by watching the survivability of fathead minnows and water fleas. Woodling has not conducted any tests on fish populations below local wastewater treatment plants.What’s good for business…But regulating what substances that will be allowed to enter the environment isn’t easy, Woodling said.”You’re looking at a culture that has changed,” he said. “We’re for business, not environmental or human health problems.”And instead of attempting to tighten water quality standards, Woodling said just the opposite is occurring. When he looked for a reference stretch of uncontaminated water during his experiment to use a a scientific control, he was not able to find one. Above the wastewater plants in rural areas the water was contaminated with antibiotics from livestock, he said. But as a point of perspective, Woodling said he believes that zinc, a metal that once dissolved is toxic to fish, may be a more urgent problem than the endocrine interrupter substances. Zinc is one of the substances emitted by the waste from the defunct Eagle Mine at Gilman.Woodling is familiar with the Eagle River. Each year he and his teams conduct a fish and bug census to judge the effectiveness of the Eagle Mine cleanup.Sewer plants can remove substances that can harm living organisms, though that can be costly, Trueblood said. “It’s just an expense,” he said, adding that those levels of treatment would boost sewer bills by up to 70 percent. “It’s all delivered to our front door.”In many instances it’s easier to ban the use of the substances instead of trying to remove them from wastewater, Trueblood said. People concerned about the quality of their drinking water can use a reverse osmosis water filtration system that will remove virtually everything from drinking water, he said.Woodling said the mutations in fish he and his team observed along the Front Range diminished significantly just a few miles downstream from the discharge point of the sewer plants. He did not sample trout populations, but said in future experiments he may include them – if enough funding is available.Woodling said the mutations in fish he and his team observed along the Front Range diminished significantly just a few miles downstream from the discharge point of the sewer plants. He did not sample trout populations, but said in future experiments he may include them – if enough funding is available.
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