PORTLAND, Ore. (KOIN) — The City of Portland is deciding how to treat its drinking water for a potentially deadly parasite — cryptosporidium.

The Bull Run water source tested positive for crypto a number of times this spring. Now, the city must make a decision on how to treat its water by August 11.

In a public hearing on Tuesday, the Portland Water Bureau presented 2 options to mitigate the parasite.

One option is to build an ultraviolet plant, at a cost of about $105 million. The other alternative is to build an entirely new treatment facility that could cost up to half a billion dollars. The new facility option could result in a 5% increase in residents’ water bills by 2020, according to the bureau.

“Yes, there are rate increases, but they are fairly low given what we have to do, ” Mike Stuhr, director of the Portland Water Bureau told KOIN 6 News.

The decision, which could reshape how Portlanders get drinking water for decades, must be agreed upon by next month.

The reason for the tight deadline stems from a 2012 mandate by the EPA for major cities to filtrate their water supply for crypto. Portland, however, applied for a waiver – known as a variance – to be exempt from that filtration because the community and city officials claimed the water was already clean.

After a series of failed tests earlier this year, in which crypto appeared; the variance is being revoked.

Now, the city must treat the water or face stiff penalties that could include a government takeover of the water supply.

Despite the presence of crypto in the water supply, there are some Portlanders who are still opposed to both options.

Floy Jones, a resident of the city, said, “They’re both nearly, equally bad options, I mean we don’t have a public health problem, we have a 125-year history of no disease in the community. We don’t have infectious cryptosporidium.”

However, doing nothing is not a “viable alternative,” according to Stuhr.

If the city does nothing and there is an outbreak due to crypto, local elected officials could face serious charges.

City council is expected to vote on the $105 million UV option or the $500 million filtration facility on August 2. Meanwhile, the drinking water in Portland is said to be safe and the detected levels of crypto are not a risk to public health at this time.