Baker City officials are asking residents to reduce their water use by watering lawns and gardens in the evening or early in the morning.
The request is related to the confirmation this morning that at least five city residents, and likely more, have been infected with cryptosporidium.
Although the source of the crypto has not been confirmed - water sample test results probably won't be available until late Friday at the earliest - if the city's water supply is responsible the most likely source is Goodrich Lake, high in the Elkhorns, both City Manager Mike Kee and Public Works Director Michelle Owen said.
As a result, the city this morning stopped diverting water from Goodrich, and switched to the city's well, which doesn't produce as much water.
In addition, Owen said she has asked major water users such as the city-owned Quail Ridge Golf Course, Mount Hope Cemetery and the Baker School District, to reduce irrigation.
Water use at Geiser-Pollman Park will be cut in half for the next few days, Owen said.
Speculation about Goodrich Lake being the crypto source is based on a few factors, Kee and Owen said.
First, the city started using Goodrich water on July 15. That date coincides pretty closely with the outbreak of crypto cases, as symptoms generally begin two to seven days after the person is infected.
"Adding Goodrich water was the only change to our system during that period (since July 15)," Owen said.
Second, there is a large population of mountain goats living near the lake, and animal feces is a common source of crypto contamination.
Finally, there is a possible link between Goodrich water and three positive tests for crypto in 2010 and 2011.
During a 12-month period the city, as required by federal law, had 24 water samples tested for crypto. Three of those tests detected small numbers of "oocysts" - the protective shell that makes crypto resistant to the chlorine concentrations that the city uses to disinfect its water.
All three of those positive samples were taken at a time when the city was using Goodrich water, Owen said. That in itself isn't proof because the city was using water from several other sources at the time as well, and water gets mixed up as it flows through the pipeline to town.
No cases of crypto contamination were reported during that 2010-11 period.
City workers today have taken water samples from Goodrich as well as from the other streams the city diverts water from.
City officials initially believed test results would take at least seven days, but Kee said Owen contacted a lab in Seattle that can test as many as seven samples within 48 hours.
A city worker will drive those samples, including one from Goodrich Lake, to Seattle early Thursday.
Although the water from the city's well actually originally came from the mountain watershed, Owen said all of that water was diverted into the well in June or earlier, weeeks before any reports of crypto.
In the meantime city workers are also inspecting each of the stream diversions to make sure there isn't an obvious potential source of crypto contamination, such as an animal carcass lodged in a diversion pipe.
Although water from Goodrich was shut off this morning, some of that water could remain in the distribution system for as long as a week, Owen said. However, the city might try to speed that process by flushing fire hydrants.
Kee said city officials had planned to drain and clean the pool at Sam-O Swim Center, but it appears there might be another option. By adding higher concentrations of chlorine for 13 hours, the city can disinfect the pool against crypto (those concentrations are much too high for drinking water). The pool is closed as of Wednesday afternoon.