Michigan Gov. Rick Snyder said Monday that 89 percent of water samples collected from key locations in Flint measured below the "action level" of 15 parts per billion for lead in an initial round of testing, but concerns remain.

Samples from the "sentinel" sites will help determine when it is safe to drink unfiltered water again. Snyder said the results are a "start" but "it's not time to draw conclusions."

Snyder told reporters that 11 percent of 175 samples exceeded the action levels, including five homes above 100 parts per billion of lead.

More data is being collected over the next seven weeks.

Utilities are required to show water from customers' taps does not exceed the action level in at least 90 percent of homes sampled.