Horsetooth headed to EPA 303d list?
Horsetooth reservoir is heading on to the EPA's impaired list, according to the Fort Collins Coloaradoan. From the article, "The U.S. Environmental Protection Agency says Horsetooth, Fort Collins' primary drinking water supply, should be placed on the list - called the 303d list - because levels of dissolved oxygen in the reservoir have failed to meet standards for aquatic life.
"Dissolved oxygen, the amount of oxygen dissolved in water, is essential for aquatic life. When it gets too low, fish die or their populations struggle.
"The EPA had also pursued the listing based on what it said were 21 failures in the last seven years by the reservoir - based on data provided by the city of Fort Collins - to meet state drinking water standards, but an EPA official said Friday the agency will drop that argument for now.
"State water quality leaders say Horsetooth should be monitored for two more years because they don't have enough data to justify a spot on the 303d list, the same recommendation they made in 2004.
"The Northern Colorado Water Conservancy District, which operates the reservoir for the U.S. Bureau of Reclamation, says Horsetooth doesn't belong on the list because low dissolved oxygen, or D.O., is only a problem in some parts of the reservoir.
"'Low D.O., if in a reservoir at all depths, is a serious issue,' said Don Carlson, assistant manager of the NCWCD.
"But Carlson said dissolved oxygen levels at Horsetooth are 'only a problem at a certain depth.'
"The state's Water Quality Control Commission will hear the case Feb. 13 in Denver...
"Fish in Horsetooth haven't suffered from the low dissolved oxygen levels because they're able to swim to depths with better levels, said Ken Kehmeier, an aquatic biologist for the Colorado Division of Wildlife and the fisheries manager for Horsetooth...
"But another question is how often dissolved oxygen levels at lower depths near the Soldier Canyon Dam - where the city of Fort Collins draws water for its drinking water treatment plant - have violated state standards. The EPA says it's happened 21 times in the last seven years...
"Prolonged low levels of dissolved oxygen near the bottom of the reservoir can cause the release of manganese from nutrients in the water. High levels of manganese can be difficult to treat out of drinking water but are seen primarily as an aesthetic problem...
"Low dissolved oxygen levels are the result of high nutrient levels. Those nutrients, including phosphorus and nitrogen, trigger algae growth and drive up total organic carbon in the water, not all of which can be eliminated by the city's drinking water treatment facility.
"The remaining TOC, when mixed with the chlorine used to treat drinking water, produces chloroform, a known carcinogen tightly regulated in drinking water by the EPA. City officials say TOC is not a problem for the city's water supply.
"Nitrogen and phosphorus enter the Colorado-Big Thompson, of CB-T, system and Horsetooth through wastewater discharges, urban development, rain (which carries nitrogen) and C-BT's own pipelines, where algae grows.
Category: Colorado Water
8:36:45 AM
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