In order to be in accordance with their interlocal agreement with Cascade Water Alliance, the city of Issaquah will have to use more water from well No. 5 — a well that is generally not used due to its levels of arsenic and manganese, city officials said Tuesday.

While the levels are not below EPA standards, they are borderline. If the parts per million of arsenic in random test results increase, or if the EPA lowers their standards any farther, the city will either have to pay penalties to the CWA to use more water, or will have to build a water treatment facility, which could cost more than $ 7.3 million.

The water is safe to drink, however.

“Our numbers were well under the old EPA number, and we are still under the new level,” Public Works Operations & Emergency Management Director Bret Heath said.

Issaquah officials originally agreed that they wanted to keep their independent water rights for the aquifer. In order to do that, they had to agree that they would contribute a certain amount of water to the city to help CWA. Originally the city agreed to supply 4.4 million gallons per day during peak hours and 2.5 million gallons per day on average. CWA produced an audit that determined that the city could only reasonably supply about 83 percent of that. However, that audit was never approved by the council so the CWA is requesting a new audit.

If the city cannot come up with the amount of water they agreed to supply, then they will receive warnings as well as fines, which could be hugely expensive. CWA is currently auditing all of its members, not just Issaquah.

To keep up with the amount of water, the city will have to use well No. 5, which so far has only been used during peak times due to the arsenic in the water. The well is 400 feet deep, and the arsenic is a naturally occurring geological condition.

In addition, the city will also start the process of blending its water with CWA for the supplies going to Talus and the Highlands. These two areas already have CWA water, which is fluoridated. So, as the city’s water and CWAs water are mixed, fluoride will be added to maintain the area’s water standard. The blending of the water should start early next year.

“It’s really just a time-consuming effort to keep it clean,” Heath said.

By Dec. 31, the city should be on the second phase of the project, which includes working on the pH balance of wells 1 and 2 on the pH balance and working on the manganese in well 5.

Manganese is not a health concern but rather a aesthetic one, officials said. Manganese shows up as small black flecks in the water that can turn water a grey color. This can also affect clothes being washed, leaving them a bit dingy. The city will use sodiumpolyphosphates to bind and carry the manganese, which can then be removed from tanks.

“We’re told it’s an effective way of dealing with it,” Heath said.

The manganese has always been in well 5 however it didn’t start showing up until after the city began chlorinating its water. Since then, the city has avoided using well 5 unless it is really needed, such as during the peak summer months. If manganese appears in the water, then the line has to be flushed.

By supplying part of its own water, the city is saving a significant amount of money. By 2010 it could save $143,000 a year at a conservative estimate, Heath said.