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By Dan Rudy 

Water quality given passing grade

 


Appearing in people’s post boxes, the results of a 2014 Water Quality Report have been released by the City and Borough of Wrangell.

The annual report is conducted in compliance with the federal Safe Drinking Water Act and provides residents details about how their water quality matches up to regulatory standards.

The town’s water originates from a pair of surface reservoirs on Mount Wrangell. The reservoirs are connected by a spillway, and raw water moves from the lower reservoir to the treatment plant.

Water entering the plant is treated with ozone to remove iron, reduce the level of organics and provide some initial disinfection. Afterward, it is run through a pair of roughing filters, then four sand filters. Chlorine is then added before being stored in the plant’s two 424,000-gallon tanks.

Because of its type and location, Wrangell’s water system has been rated highly susceptible to contamination from nitrates, bacteria, volatile organics and heavy metals. However, testing of the water has shown it to be of passable quality, well within national standards in most cases.

A by-product of chlorination, Wrangell’s haloacetic acid levels ranged from 22.7 parts per billion (ppb) to 116, coming in at 57 ppb on average. Total trihalomethanes ranged between 9.8 and 49.9 ppb, at an average of 28.622 ppb; this falls well below a maximum residual disinfectant level of 80 ppb. Similarly, bromates tested at 1.1 ppb, below the 10 ppb maximum.

Inorganic contaminants included trace amounts of barium, chromium and nitrate. These typically come from erosion of natural deposits but can also occur from industrial discharge, fertilizer runoff and septic tank leaching.

Also typically coming from erosion, some trace radioactive contaminants were detected in the water. Measured in picocuries per liter (pCi/L), radium was detected at a level of 0.195, well below maximum contaminant guideline levels of 5 pCi/L. Alpha emitters read at 0.77, below a maximum of 15 pCi/L.

Copper levels were also reported at a low 1.17 parts per million, below a goal of 1.3. Trace amounts of nickel were also recorded.

Lead, on the other hand, was reported at 7.29 ppb; while half the actionable level of 15, the Environmental Protection Agency (EPA) has set a maximum contaminant level goal of zero. The EPA website explains that this level was set based on the best available science, which indicates there is no safe level of exposure to lead.

Unlike other typically found contaminants, lead found in drinking water most often is a result of corrosion of the plumbing materials belonging to water system customers. When contaminant levels are such that action is needed, treatment guidelines require tighter management of water systems’ water corrosivity to mitigate contamination, rather than a more direct method.

An electronic copy of the report is available on the City and Borough of Wrangell’s website, http://www.wrangell.com, under the Public Works section. Paper copies can be retrieved from City Hall. For more information on the report, contact the Public Works Department at 874-3904.

 

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