Cleansing Carson City water of arsenic could come with a price tag of $3 million to $4 million, and that's only if the city's ideas for handling the heavy metal pan out.
Original estimates of treating city water suggested a cost closer to $6 million or $7 million, but Carson City public works officials have some newer plans.
City supervisors approved a $200,000 contract Thursday to test the ideas and prove to state environmental regulators that cheaper methods will work.
The arsenic level of all 28 municipal wells fall well below the old drinking water standard of 50 parts per billion, but seven won't meet a new mark of 10 parts per billion, set to take effect on Jan. 23.
Carson City's groundwater meets all other environmental standards, so there is no central treatment plant that would mix it all together before putting it into the system. If there were, the city would likely have no arsenic problem at all.
Without a central plant, water drawn from the wells goes straight into pipes that supply homes and businesses throughout the city.
Although the arsenic-tainted water likely mixes with cleaner water already in the pipes, residents closer to arsenic-bearing wells do face a chance of receiving water above the new federal regulation, said Public Works Operations Manager Tom Hoffert.
As it is, the higher-arsenic wells are only used the two or three months a year when water usage is at its peak, usually July, August and September, Hoffert said.
Four of Carson City's seven offending wells are so near the new standard, ranging in arsenic content from 11 to 13 parts per billion, that a little clean water mixed into the wells will fix the problem.
On the other three wells, which produce water with 17 to 23 parts per billion arsenic, the city plans on using a variety of methods, from injecting arsenic-free water into wells to the more expensive approach of filtering out the metal.
Carson City is also asking the state for a three-year extension of the arsenic standard deadline.
About 30 other communities in Nevada are also seeking more time, including Indian Hills General Improvement District, Gardnerville Ranchos, Sunrise Estates and the East Valley Water System, all in Douglas County.
In Lyon County, the Silver Springs Conservation Camp and Weed Heights have applied for extensions.
State health officials expect more communities to ask for extra time as the deadline nears.
Only communities with average arsenic concentrations below 35 parts per billion qualify for the three-year extension.
After that, they could receive a total of three two-year extensions, depending on how high the arsenic level is.
The standard applies to all water systems in the nation that serve 30 or more people or have at least 15 hookups to the same source. About 140 such systems are in Nevada.
Arsenic is a naturally occurring heavy metal that has been linked to skin, bladder and lung cancer.
The highest concentrations of arsenic in the United States are found in the Southwest.
n Contact reporter Cory McConnell at cmcconnell@nevadaappeal.com or 881-1217.
