As Arnold waits to see how high Meramec will go, the river has begun receding in Eureka, Pacific

Floodwaters from the bloated Meramec River have begun receding in Eureka, Pacific and Valley Park, but downstream in Arnold, the water continues to rise, with southbound lanes of Interstate 55 shut down and northbound expected later Wednesday.

In Pacific, where city officials have issued a boil order, the water rose to about 33 feet Tuesday, just short of the December 2015 record. It was beginning to fall rapidly. The river crested Tuesday night in Eureka at just over 46, almost exactly at the 46.1-foot record from 16 months ago. The Meramec River in Valley Park is expected to crest early Wednesday afternoon, at just over 44 feet. At noon, it was just over 43 feet.

In Arnold, the river continues to rise, currently at a few inches over 45 feet, with an expected crest of 46 feet.

"We would like to remind everyone not to drive through flooded roadways, and remain patient," said Matt Gabrian, a spokesman for the St. Louis County Police Department.

Gabrian also advised people to stay out of the rising water.

"Flood waters often contain infectious organisms, including intestinal bacteria such as E. coli, salmonella, and shigella, Hepatitis A virus, and agents of typhoid, paratyphoid and tetanus," he said.