The 55-year-old officer, whose nearly two decades of command in the Army Corps of Engineers includes a stint in Iraq and helping oversee the restoration of the Gulf Coast after Hurricane Katrina, is choosing now whether to blow a massive hole in the Birds Point levee in southeast Missouri. Doing so will drown 130,000 acres of rich farmland and destroy 100 homes. Opting not to risks that flooding will wipe away the entire town of Cairo, Ill. It also has consequences on the entire levee system.
While waters and emotions rise, the straight-talking Walsh has maintained a business-like demeanor. He's met with people on both sides of the river, some of them angry or upset about the plan, which aims to relieve pressure on the flood wall at Cairo, a long-struggling community of 2,800 residents. In answering people's questions, he's often cited statistics or protocol. And he's shown empathy, if not emotion.
"I recognize all of your lives will be impacted," he told one group of Missouri property owners last week. "But these levees have never been under this pressure before."
Even those opposed to the Corps' plan appreciate how Walsh -- who is responsible for managing the entire length of the Mississippi River valley, from Canada to the Gulf of Mexico -- has handled the situation.
"The general has a very difficult decision to make relatively quickly," said Missouri Gov. Jay Nixon, whose administration opposed the plan all the way to the U.S. Supreme Court, which declined to intervene. "He understands the magnitude of the decision on his plate."
Nearly everyone is already out of Cairo. Mayor Judson Childs ordered mandatory evacuation after a massive sand boil was discovered, creating fears of an uncontrolled levee break. Walsh could decide on making a deliberate break on Monday. Barges have brought explosive devices to the site, about 130 miles south of St. Louis, and Corps workers have begun loading them onto the levee. The Corps said the explosion could occur as soon as three hours after Walsh gives the command.
Since the floodwaters began to rise to near record levels last week, rhetoric has been harsh from both sides of the river. Missouri officials not only condemned the idea of blasting the levee but filed suit to stop it. Childs last week implied racism was at play, saying Cairo -- a community that is 70 percent black -- was on the "verge of being the next 9th Ward of New Orleans," referring to damage caused by Hurricane Katrina.
If Walsh is feeling pressure, he's not showing it, nor is he talking about it -- Walsh declined interview requests for this story.
He said last week, though, that he would rather use the controlled levee break to ease the floodwaters than do nothing and risk seeing a levee burst or be topped elsewhere where more lives and less farmland were at risk, and insisted he's not taking the decision lightly.
Walsh "has lived up to his reputation, Nixon said. "He's very sharp and focused on the job at hand."
The native of Brooklyn, N.Y., assumed his first command in San Francisco in 1994, moved to Sacramento, Calif., and then onto Corps headquarters in Washington, eventually becoming chief of staff. In 2004 he took command of the division in Atlanta, then went to Iraq, where he was commander for the Corps' Gulf Region Division. Walsh took command of the Mississippi Valley division in 2008, a region that includes portions of 12 states and encompasses 370,000 square miles.
Until now, the married father of two has kept a relatively low profile -- except for one word he said in June 2009.
During a Senate hearing on the Gulf Coast restoration, Sen. Barbara Boxer took exception to Walsh's reference to her as "ma'am."
"You know, do me a favor," the California Democrat said. "Could you say 'senator' instead of 'ma'am?'"
"Yes, senator," Walsh responded, though military officials quickly pointed out that protocol directs that officers may use "sir" or "ma'am" when addressing those above them in the chain of command.
Now, the general faces stakes far greater than hurt feelings.
Robert Jackson, a commissioner in Mississippi County, Mo., who owns 1,500 acres in the floodway, became animated and even mildly cursed during the forum in East Prairie, saying that blasting the levee would not only damage farm land but undo millions of dollars of work the county has done on everything from roads to ditches.
Walsh remained calm, but stood firm that all options were on the table. And Jackson said later that he understands what the general is up against.
"Human lives come first," Jackson said. If people died because a levee broke downriver, "They'd drag him in front of a Senate committee tomorrow to answer for it."