FLINT, MI -- The U.S. Environmental Protection Agency has concerns about the city of Flint's ability to distribute chlorine throughout the water system during the summer months.

"With the onset of warmer weather, the situation is urgent," the EPA states in a June 3 letter to Flint Mayor Karen Weaver and Michigan Department of Environmental Quality Director Keith Creagh.

The letter instructs the state DEQ and the city to expedite planning, permitting and installation of chemical feed equipment by June 10.

Flint Mayor Karen Weaver the city is aware of the issue and they are working to address it.

"We've been in contact, not only have we heard from the EPA, but we also have been in contact with the state and we're working to get this fixed and to stay on top of things," Weaver said. "We're gonna try to do this as quickly as possible. One thing we want to do is make sure we don't rush anything, so we don't end up in another bad situation again as well. So we really have to be careful as we do this and make sure we have everything in place, but we are working to address this situation."

MDEQ spokeswoman Melanie Brown said the agency and the city are working together to resolve the issues.

"The city, DEQ and EPA continue to identify and resolve issues relative to the water treatment system," Brown said in a statement. "We are in the process of working directly with the city to resolve the issues raised in the letter."

The EPA's Safe Drinking Water Task Force has been concerned about chlorine residual levels in Flint's water since meeting with the Utilities Administrator in January, according to the letter.

"It is encouraging that EPA sampling this week has shown adequate chlorine residuals at each of the 24 sites we tested. However, as chlorine decay increases with warmer water temperatures, EPA is concerned that the Respondents will not be capable of maintaining chlorine residuals that follow best practices and are protective of public health. In particular, we are concerned that while the City can add chlorine at its Cedar Street and West Side Reservoirs, this additional chlorine does not reach the entire distribution system. The City does not currently have the equipment or means of adding additional chlorine or caustic at the Flint Water Treatment Plant (WTP) to consistently protect public health throughout the distribution system." the letter reads.

While water from Detroit arrives in Flint with a chlorine residual, it is necessary for Flint to have the capability to boost the level of chlorine in the level of chlorine in the water to maintain a residual throughout Flint's distribution system, according to the letter.

Due to the EPA's concerns, the agency has been engaged with the MDEQ and Flint for several months to ensure the maintenance of chlorine levels. This included the EPA's monitoring of 24 locations geographically spread throughout Flint's distribution system, according to the letter. Also part of the EPA's field sampling response in Flint, more than 800 chlorine residual samples have been taken at residences from January of this year until May.

In addition to the testing, the EPA worked with the city to install 13 automated flushers on hydrants in areas with lower chlorine residual levels to help move water through the distribution system and to improve chlorine levels.

The EPA warns in the letter that the situation is urgent. In a May 26 meeting at the Flint Water Treatment Plant, the need to expedite the ability to boost chlorine in the distribution system was discussed with the city and MDEQ, according to the letter. The EPA believes the city and state must take immediate action to implement a temporary solution even as a long-term treatment system is developed and put in place.

"Based on our recent discussions, EPA understands Respondents intend to ensure that a temporary chlorine feed is installed at the Flint WTP as soon as possible. On June 1, 2016, MDEQ approved the City's temporary sodium hypochlorite and sodium hydroxide feed system approach and are awaiting the submittal of final plans for permit issuance. The approval letter did not provide an estimate date of installation, but we understand from our call on June 2, 2016 with the City and MDEQ that a June 10, 2016 target date for the temporary feed system can be met. In addition, EPA suggests that the City purchase backup chemical feed systems in case of failure of current and future systems operated by the utility. Loss of disinfection and loss of phosphate feed may result in adverse water quality reactions that can take place rapidly." the letter reads.

In addition, the EPA Task Force recommendation is that the city maintain target pH levels in the distribution system to ensure that orthophosphate treatment is effective. The chemical feed installation should include both the ability to add sodium hypochlorite to boost chlorine residual and to add caustic soda to address and correct low pH levels in the distribution system in order to ensure that orthophosphate treatment is effective and lead release in minimized, according to the letter.

Both infants and children have tested positive for elevated levels of lead in their blood since the city switched to using the Flint River as its water source in 2014.

In January, the state announced there were 87 confirmed Legionnaires' cases from June 2014 through October 2015. Of the 87 confirmed cases, nine people died.