The flood season in the nation's midsection started early this year, and there's no letup in sight, spurring federal, state and local officials to brace for what looks likely to be an unusually watery spring.

At least 16 deaths were linked to heavy flooding across Missouri, Arkansas, Tennessee, Oklahoma and other states in March; another was tied to flooding Friday in Kentucky. Last week, snow that could set off more flooding blanketed parts of the Midwest. And Kentucky and parts of Arkansas and Missouri that are struggling to recover from previous deluges remained vulnerable to the threat of weekend rain.

State and local agencies and the U.S. Army Corps of Engineers have been ramping up their readiness efforts: stocking up sandbags and other emergency supplies; inspecting levees for groundhog holes and errant trees that can take root and weaken them; and holding regular multi-agency meetings.

"What can you do?" asked Missouri State Emergency Management Agency spokeswoman Susie Stonner, noting that this year's first flood came a month earlier than usual. "You can store sandbags -- that's about it. A lot of communities already experienced flooding. Some of them are pulling sandbags back, putting them in areas where they can utilize them again. People are leaning forward in their foxholes."

In Poplar Bluff, Mo., where flooding from a March levee break destroyed a number of homes, city clerk's assistant Lori Phelps said traumatized locals are hoping the predicted rains will not cause more floods.

"There's not a lot you can do -- just sit and hold your breath," she said.

Throughout the region, the Corps of Engineers has been releasing excess water from reservoirs into already swollen streams. The Wappapello Reservoir in southeast Missouri rose 11 feet in one day during severe rainfalls in late March.

"One of the purposes of these reservoirs is flood-damage reduction," said spokesman Alan Dooley of the Corps of Engineers' St. Louis District. "The water flowing in dictates how much is allowed to flow out. We do this with an eye to retaining as much as possible and discharging it later when streams are better equipped to handle it."

On March 5, officials of the Corps of Engineers, the Federal Emergency Management Administration, the Coast Guard and state agencies met for a flood mitigation summit at the Rock Island Arsenal in Illinois, the first such meeting held in the Upper Mississippi River Basin.

The Corps of Engineers' Rock Island District, a regional distribution center, replenished its supplies of more than 1 million sandbags, almost 100 pumps, 1,000 feet each of rapidly deploying flood walls and Portadams and 2,500 rolls of plastic sheeting.

In the Midwest, flood season started before winter's end as heavy snow alternated with warm weather.

"If rain falls on top of snow, the risk of flooding is much greater than any other time of year," said Kevin Trenberth, head of climate analysis at the National Center for Atmospheric Research.

Illinois got its first floods in January, earning federal disaster designation for several counties. Ice jams, formed when floes collide and block a river's flow, also caused flooding in the Quad Cities area in the winter.

National Weather Service hydrologist Noreen Schwein said the recent flooding has been caused by large frontal low-pressure systems, more common in fall and winter, that linger over a region for long periods.

"In spring, we'll transition to more severe weather systems that move through more rapidly," she said. That likely means fewer consecutive days of rain in one place, but the deluges can still cause serious flooding.

For cities in the Great Lakes region, flooding often results in untreated sewage overflowing into rivers and the lakes.

"With spring rains, we will see overflows everywhere in the region," Jeff Skelding of the National Wildlife Federation said. The federation is part of a coalition seeking federal funding to help municipalities overhaul aging, overburdened sewer systems. "It's a problem for public health, for beaches. It's a chronic problem in the Great Lakes that's not going to go away without congressional action," Skelding said.

The National Weather Service has tried to prepare the public, holding a flood safety awareness week March 17-21 and, among other things, urging people to "turn around, don't drown" when they come to flooded roads.

"Flooding causes more deaths than any other weather phenomenon," Weather Service spokesman Patrick Slattery said. "A lot of people take on low water crossings thinking they will be fine and then find out they're not."

Because floodwater from the Midwest and Ozark regions ends up in the Mississippi River, the March floods and more spring flooding could also put the Katrina-ravaged Gulf Coast at risk. Currently, the Mississippi is so swollen that officials are considering opening the Bonnet Carré Spillway for the first time since 1997 to divert water from the Mississippi into Louisiana's Lake Pontchartrain.

Trenberth said heavier flooding is one of the widely predicted effects of global warming, because higher ocean temperatures mean the air can hold more moisture for storms to draw from.

"When it rains, it pours, and even when it snows, we will get heavier snowfalls," Trenberth said. "Whether that converts to flooding depends on what mitigation factors have occurred on the ground."