Flooding, according to Howard County's 2004 Natural Hazards Mitigation Plan, "is the most common natural disaster to impact Howard County."
Flooding is well-documented in the county — moreso than earthquakes or tornadoes, for example — and has taken lives and caused millions of dollars in damages over the years.
Located entirely within the watersheds of the Patapsco and Patuxent rivers, the county is susceptible to swollen rivers and to flash floods at any time of the year and should be prepared for them, the mitigation plan says.
"There's no question it is our top hazard, so we've taken it real seriously," said Ryan Miller, deputy director of the county's Office of Emergency Management.
Unfortunately, the county learned the hard way.
Forty years ago this month, when Tropical Storm Agnes rampaged through Howard County on June 21 and 22, 1972, there was no comprehensive county plan in place for flooding, officials said.
Many local residents were caught off-guard by the rapidly rising waters that flooded historic Ellicott City, washed out bridges and roadways and caused widespread damage in Elkridge and other low-lying areas of the county. Some were trapped on second stories of their homes, some on roofs.
County roads, sewage treatment services and other resources were overwhelmed — ill-suited and under-equipped to deal with the devastation, local officials recalled.
Members of the professionalized Howard County Department of Fire and Rescue Services, which was in its infancy at the time, recall having little rescue equipment and using rope, flashlights and flat boats not meant for swift currents to perform daring rescues in raging waters.
Data on storm water levels was slow to come in or unreported altogether, as there were relatively few gauges throughout the region's watersheds.
Without many of the early-warning systems of communication in place today, businesses and homes were suddenly flooded with little or no advance warning.
As a direct result of the storm, a flood warning system was instituted for historic Ellicott City, and according to county officials, changes to how the county mitigates vulnerabilities and plans for natural disasters have continued to be rolled out ever since.
The county now prohibits structures from being built in flood-prone areas and has a program for purchasing and demolishing structures already there.
It has a team of storm water management professionals who monitor a series of gauges throughout the two watersheds during large storms and predict rises in water levels at various points throughout the county — allowing them to sound alarms and warn emergency personnel before flooding begins.
The county has a network of contacts in communities that are most vulnerable to flooding, who provide county personnel with critical information and eyes and ears on the ground ahead of and during major storms.
The county also has put together grant funding for business owners in flood-prone areas who want to move their utilities off the ground. It has created NotifyMeHoward, a message alert system to send out early warnings.
The county is also working on a new version of its 2004 hazard mitigation plan, with updated data and information.
In all, Miller said, the county is far more prepared for flooding than it was in 1972.
Not that there aren't lessons still to be learned.
After the flooding in historic Ellicott City during Tropical Storm Lee last year, local residents complained that the county had done a poor job maintaining the stream beds that cut through the town before meeting the Patapsco.
Debris that had built up in the streams, including in the Tiber tributary, contributed to currents backing up so badly that the streams flooded homes in the west end of Ellicott City, above the more historically vulnerable portion of town, residents said.
"All of the water came down, not from the river itself this time, and obviously that all comes from development and not dealing well with storm water management," said Len Berkowitz, owner of Great Panes Art Glass Studio on Main Street for more than 30 years, whose shop sustained almost $30,000 in damages during Lee.
Berkowitz said the county is trying to work with the community to fix remaining problems and mitigate additional sources of storm runoff uphill from the town. But rushing water coming downhill, through and under some of the historic town's oldest buildings, is a harrowing sign, he said.
"If one of those buildings had caved in, it would have flooded the whole town, without a doubt," Berkowitz said of Lee, and the debris it smashed against buildings' support beams.
The county is now in a procurement phase to hire a contractor to map the stream beds and their geographic features, in part to identify obstructions and remove them, Miller said.
"Ellicott City is in kind of a fish bowl, if you will, and has survived a lot of floods," Miller said. "But there are certainly some things that we can do, like to make sure the culverts are sized properly and clear."
The county will continue to learn lessons and find new ways to mitigate vulnerabilities to flood waters in the years to come, Miller said.
But county residents can do their part as well, he said.
They can sign up for NotifyMeHoward and identify ways to safeguard against high waters by keeping valuable property off the ground. They can also purchase flood insurance using the new rate maps for the county just released by the Federal Emergency Management Agency.
Perhaps most important, they can learn lessons from past flooding in the county, Miller said, such as not to drive into what appears to be shallow water during flooding, an action that has killed people in the county in the past when the waters suddenly rose and washed their cars away.
"If we can somehow weave in some personal preparedness, like not driving through standing water, that would be great," Miller said.