Baker City Manager Mike Kee said recently that the city's water supply could be protected against cryptosporidium within 12 months with the installation of an ultraviolet light treatment plant.
Our question is whether it's good enough.
Although crypto has been the focus of the city's efforts for the past several weeks, and rightfully so, the parasite is hardly the only water-treatment threat the city faces.
And UV light, though effective against crypto, is no defense against some of those other threats.
Until late July, the possibility that the city's water could sicken something like 10 percent of our population seemed somewhat farfetched. It had never happened before, so far as we can tell, in more than a century of sustained sipping from the very same streams and springs.
Yet now we know better.
And it would be a pity for us to make the same mistake twice.
The federal law that requires the city to protect its water against crypto would have taken effect whether or not the city ever found a single crypto oocyst in its water.
In other words, federal officials don't need actual proof of contamination to mandate a level of water treatment, they need only to show a potential risk.
In the case of crypto in Baker City's water, that risk has proved to be real.
Yet there are other possible threats to the city's water that a UV plant can't deal with.
A wildfire will burn some portion of the city's 10,000-acre watershed - the only uncertainty is when the fire will happen, and how many acres it will cover.
A wildfire likely would temporarily foul any nearby stream with ash and dirt, contamination that UV can't remove but a filtration plant, in some cases, could.
It's not likely that a fire would spread over the entire watershed, which means the city probably would be able to continue using some of the watershed streams during and immediately after a blaze. However, the timing would almost certainly be troublesome, since most fires happen during summer, when the city's water demand peaks. To that end, the city is wise to be looking for wells and other supplementary sources.
Another threat is the federal government.
Baker City already is an outlier among public water systems in that it doesn't have to filter water from surface sources. Just three other Oregon cities are also exempt from filtration: Bend, Portland and Reedsport.
But federal officials have shown, with the pending rule regarding crypto, that the trend is requiring cities to do more to safeguard drinking water supplies.
We're not comfortable in assuming that the rule requiring cities to protect unfiltered surface water against crypto will be the last such mandate. Future rules could involve inorganic contaminants, such as heavy metals, that filtration can remove but a UV plant can't.
The downside to filtration is cost. In 2009 an engineering firm estimated a filtration plant would cost $17.7 million, with annual operating costs of $332,000. The comparative figures for a UV plant were $2.3 million and $13,000.
But we don't know how much a filtration plant would cost residents, in the form of higher water rates. Sen. Jeff Merkley, D-Ore., is sponsoring legislation that could allow the city to borrow money and repay it over a longer period than is allowed under current programs.
Ultimately, the price for filtration, and the long-term protection it would give us against threats both environmental and regulatory, might be too high to justify regardless of the theoretical benefits.
But our elected city councilors, who make these decisions on our behalf, can't make a fully informed choice if they don't demand that the city staff provide them with all the relevant data about other alternatives, and if they don't have a frank discussion about the future of our water supply.
Certainly no one would argue that UV, though cheaper initially, would turn out to be a bargain if the UV plant no longer keeps our water safe five years from now, or 10, and we're forced into filtration.