(CNN) -- Two fires have merged, coming dangerously close to protected areas in Florida's Okefenokee National Wildlife Refuge.
The so-called Honey Prairie fire, which has been burning since late April, united with another blaze called the Paxton Road fire Tuesday, the U.S. Forest Service said.
Working around the clock, 526 firefighters have been deployed to combat the flames.
"We've got lots of crews out there trying to hold that line, trying to protect that wildlife refuge," Forest Service public information officer Haven Cook said.
Cook said while the fire is 75% contained, dealing with a fire in swamp can be tricky.
"When we're dealing with a situation like this, the fire can lay down, creep under all that peat, and so when we have significant weather like a wind event, it can spark and develop an active flame front very quickly from there."
The fire reached the eastern edge of Okefenokee Swamp to Chesser Island, a tourist attraction that housed an observation tower and a 4,000-foot boardwalk that stretched out into the middle of the swamp.
"The tower is fine; so is the historic Chesser Island homestead," Cook said. "But the boardwalk did burn; about 90% of it burned."
Florida Gov. Rick Scott declared a state of emergency Monday, citing the ongoing danger of wildfires and drought conditions.
Meteorologists say there are moderately good chances for rain toward the end of the week, but thunderstorms may also be in the forecast.
"This fire can go on for weeks until we get a good drenching rain," Cook said. "The firefighters are going to be monitoring this and watching this for two, maybe three weeks because it's been such a dry year."