Expanding on 25 years of working together to keep your water clean, the Lewiston Water Division and Auburn Water District are building a federal government-mandated Ultraviolet Light Disinfection Treatment Facility. That collaboration across the Androscoggin River will save $2 million a year.

But don’t get the impression that this means your water is anything less than clean and safe already. Out of 50,000-plus municipal water systems in the country, the Lake Auburn watershed is one of only 50 or 60 protected so well that the water doesn’t need to go through expensive filtration.

A new ruling by the Environmental Protection Agency requires two forms of disinfection. In this officially “green” project, we will continue to use chlorine along with the new UV treatment. In order to kill and inactivate organisms such as viruses, bacteria, and protozoa that might be in the water, we will dose the water carefully to meet mandated levels of inactivation, whether those organisms are present or not. Keeping the organisms out is still our best defense, so protection of the lake is of utmost importance.

UV reactors provide further disinfection by treating the water with ultraviolet light, which inactivates organisms and renders them unable to cause disease. UV is not a chemical and does not linger in the water. In order to keep a disinfectant in the water, we will continue to use chlorine but likely at a lower dose.

Lewiston and Auburn water utilities hired Camp Dresser & McKee of Cambridge, MA, to help settle on the best approach, with an eye to ensuring that our long-term plans stay in compliance well into the future. We examined 64 options, narrowed them to 16, and ended up with the existing chlorine treatment as well as UV. Our criteria were effectiveness, cost and ease of construction.

The UV Facility will be built at the existing Lake Auburn Treatment Facility in two phases costing $12 million, with the first one — installing the UV reactors and pumping for untreated water — to be finished in June. Phase 2 includes expansion of the UV building to accommodate chemical treatment, a laboratory, and administration, and will be completed next year. Water utility staff from both Lewiston and Auburn systems will operate and maintain the new facility.

Your two water utilities have been working together to meet federal Safe Drinking Water Act requirements since 1986, as well as the 1996 and 2006 amendments to that law. As noted above, we’re exempted from the law’s filtration requirement because we’ve done such a good job of protecting the watershed from contamination and keeping the water quality at a high natural level. Of course, we still have to treat the water, but it’s much less expensive to treat than polluted water.

Back in 1996, we worked together to build an intake structure in Lake Auburn to bring water into the treatment buildings. We’ve shared chemical treatment systems and have a combined drinking water laboratory for testing. Certain staff positions, such as the water quality manager and the SCADA (systems control and data acquisition) technician, are shared within the utilities.

The new Ultraviolet Light Treatment Facility is funded in part by federal stimulus money approved by Congress in February 2009. Lewiston and Auburn submitted a joint application for funding under Maine’s State Revolving Loan Fund. We received $7.7 million for Phase 1, split this way — $2.35 million in a grant and the remaining $5.35 million in an interest-free loan. Phase 2 will cost about $3.3 million and will be funded by other mechanisms typical of water utility funding. Lewiston and Auburn are funding the project through water bonds. With change orders, the first phase came to $8.6 million. The project will raise rates.