Casper’s effort to lower selenium levels in its water during the coming year will be tested in 2018 when the city’s wastewater treatment plant must apply for a new permit from the Wyoming Department of Environmental Quality.
If the DEQ finds that selenium levels are too high, it could require Casper to build a facility to remove the chemical, potentially costing the city up to $50 million.
In anticipation of future infrastructure needs, the Casper City Council on Tuesday night set…
“We have been very concerned about pending potential EPA regulations that might require us to make some major upgrades,” said councilman Charlie Powell at a Dec. 21 council meeting.
While the DEQ grants permits to wastewater plants, the agency relies on the federal Environmental Protection Agency guidelines.
Selenium is a heavy metal that naturally occurs in the Cody Shale formation that lies under most of Natrona County. Selenium can break off from the shale and become mixed with soil and leach into groundwater and irrigation runoff.
While small levels of selenium are healthy, in high levels the metal can be toxic to both humans and aquatic life. Humans can tolerate much higher levels than fish and waterfowl.
In 1998, the DEQ designated 37 miles of the North Platte River as an impaired waterway due to high selenium levels.
Based on 1999 regulations, the EPA currently allows the county to treat the high selenium levels by working with local landowners, especially those who irrigate, who wish to voluntarily reduce selenium runoff from their land.
Lisa Ogden of the Natrona County Conservation District said her organization encourages converting dirt ditches to pipelines and using sprinkler systems instead of flood irrigation to cut down on the amount of sitting water on land around the county.
“That does minimize how much selenium is taken up into the water,” Ogden said.
While Ogden said the county has seen a steady reduction in selenium levels since the 1990s, the risk faced by Casper is that new EPA recommendations might no longer allow the current pollution mitigation strategy of cutting down on selenium runoff across the county.
Instead, Casper may be forced to treat high selenium levels at a single point: the wastewater treatment facility.
Federal regulations currently require selenium to be kept below 5 micrograms per liter in waterways and below 50 micrograms per liter in drinking water.
Ogden said that based on monthly tests the North Platte River has exceeded the 5 microgram limit only three times in the last 15 years.
You have free articles remaining.
However, the wastewater treatment plant in Casper takes in water that has 8-12 micrograms of selenium per liter, according to public utilities manager Bruce Martin.
“It’s about 8 to 12 coming into the plant and about the same going out,” Martin said.
But once the treated wastewater, with its high selenium levels, is deposited into the river, it disperses and falls below the EPA limits, Ogden said.
The new EPA recommendations are more detailed than the 1999 standards, but states are not required to adopt them.
The agency specifically noted that states can set their own “site-specific” regulations for selenium. Ogden said the hope is that when the wastewater treatment plant’s permit comes up for review in 2018 the DEQ will take into account the county’s unique circumstances.
Ogden said concerns about selenium in water originated at mines where the chemical discharge killed birds and fish in huge numbers. In such cases it is easy to treat the source of pollution — a mine — and stop the selenium from entering waterways. But that’s not the case in Natrona County.
“We are sitting on the Cody Shale,” she said. “It’s not like you can shut down geology.”
If the new EPA recommendations do force single-point treatment, Martin said that will put the city in a jam because there is little that can be done at the Sam H. Robbs Regional Wastewater Treatment Facility — without spending tens of millions on a new facility — to lower selenium levels in the water it treats.
Sometime in the next decade, Casper will likely have to spend anywhere from $24 million to $…
“As it sits right now, with our current treatment we wouldn’t be able to meet a limit — depending on what that limit was,” he said.
Martin said that the city was currently working with a consultant to explore options to reduce selenium levels at the wastewater plant and both the city and county fund the conservation district.
Ogden’s work is focused on ensuring other waterways in the county, especially the North Platte River, have low enough selenium levels that the wastewater plant’s discharge does not bring the entire river above allowed thresholds.
“If we keep it low in the river, then what comes through the wastewater plant will mix and be low enough,” she said.
The DEQ employee who has been working on selenium issues in Natrona County was out of the office for the holidays and unable to comment.
Powell, the councilman, said the city was making progress but it appears that what happens over the next year will be a serious test for water treatment in the region.
“EPA is watching us very closely,” Powell said. “We hope those levels will continue to come down so the EPA will say, ‘They’re low enough, you’re safe and you don’t have to spend $50 million.”
Be the first to know
Get local news delivered to your inbox!