LONGMONT — Portions of the St. Vrain River turned tomato red Wednesday as federal scientists studied how fast the water flows downstream.
Workers with the U.S. Geological Survey poured small amounts of nontoxic red dye into the river at two spots, by Airport Road and by South Pratt Parkway. They then waded into the water every five minutes at several places downstream to collect samples they would later test to see how fast the now-invisible dye arrived.
Scientists will use the information to conduct a water-quality study Monday, tracking how water picks up contaminants as it passes through the city, both above and below the city’s sewage-treatment plant.
“It will help us better understand how the urban environment and people affect water,” said Bret Bruce, project chief for the ongoing USGS study of the South Platte River basin.
The St. Vrain joins Boulder Creek east of Longmont and eventually becomes part of the Platte River.
Along the way, those rivers pass through dozens of communities large and small, and scientists are trying to figure out exactly what kinds of modern chemicals are passing through our bodies and into the water. They’re also looking at compounds leaching from plastics and other manufactured goods.
Traditionally, wastewater-treatment plants remove bacteria and chemicals such as ammonia and nitrogen from the water. But city officials know the federal government will likely in the next decade require them to remove other contaminants, such as caffeine, antacids and birth-control hormones.
That’s going to cost taxpayers money, and city officials want to do what they can now to reduce the amount they’ll eventually have to spend. Interim steps could include building wetlands where plants would filter out chemicals.
There are but few studies showing the effect of low levels of these compounds on aquatic life, and scientists are hoping studies such as the one on the St. Vrain will help them learn more.
USGS experts have already begun studying the “bio-accumulation” of such compounds in animals living in the river. Material that mimics the way living tissue absorbs chemicals were placed in the river over the last month and removed last week.
“They’re (designed) to mimic fish tissue,” Bruce said. “You never know where fish have been, so this gives us a better feel for what’s passed over the field of study.”
Those filters are now being studied to see what contaminants they collected. Longmont city officials, who requested the USGS studies, will start getting information about water quality over the next few months, with a final report ready in a year.
“I’d like to be ahead of the game and try to address some of these things,” said Cal Youngberg, the city’s water-quality director. “Wastewater plants aren’t designed to remove those compounds.”
Trevor Hughes can be reached at 303-684-5220, or by e-mail at thughes