When Storm Sandy slammed into the Atlantic Coast Monday night, it dumped upward of six inches of rain on Harford County, flooding streams, creeks and ditches and raising the possibility that the Susquehanna River could swell in the coming days as the storm's remnants pass through Pennsylvania.
Locally, however, the flooding was comparable to what's typical of a heavy summer storm, raising the level of streams like Deer Creek, Winters Run and Little Gunpowder Falls enough to force the closure of some roads Tuesday morning, including Harford Road.
By midday Tuesday, Little Gunpowder Falls at Laurel Brook Road in Fallston was flowing at 533 cubic feet per second, about 20 times its average flow for this time of year, according to the U.S. Geological Survey. That was nowhere near the level reached on Sept. 8, 2011 when the same USGS gauge recorded a flow of 5,000 cubic feet per second in the aftermath of two named storms passing through. A cubic foot is roughly equal to 7-1/2 gallons.
Similarly, Deer Creek at the Rocks gauge had a peak flow of nearly 4,000 cubic feet per second Tuesday and was receding by 3 p.m. This flow was about 60 times the stream's median flow of 63 cubic feet per second, but substantially less than the more than 7,000 cubic feet per second recorded on Sept. 8, 2011.
The storm caused flooding in low areas of Havre de Grace along the Susquehanna River and Flats, though, again, nothing comparable to last year's high water, and substantially less damaging than the Isabel storm that caused a Chesapeake storm surge that ended up ripping out the popular Promenade at the mouth of the Susquehanna.
On Tuesday, the Susquehanna remained swollen and moving briskly past the city, with the Municipal Yacht Basin flooded and the parking lots around the Jean Roberts Memorial Park area also covered with water.
City police were keeping people away from parks and other low lying areas along the river Tuesday morning, although the storm surge to that point did not appear to be significant.
The full impact from the river remained uncertain, however, as Havre de Grace Police spokesman Jeff Gilpin said low-lying areas could see more flooding during high tide later in the day as tides changed.
Concerned about large volumes of water coming from farther up the river in Pennsylvania and New York and with the approaching high tides, Harford County emergency officials were, as of Tuesday morning, still advising people living in lower areas Havre de Grace to consider evacuating.
The U.S. Geological Survey gauge on the Susquehanna River at Harrisburg, Pa., the nearest gauge not affected by the opening and closing of gates on dams, showed a sharp increase in flow from about 14,000 cubic feet per second, a fairly typical flow, to nearly 60,000 cubic feet per second. The increase occurred over a span of about 12 hours and the water level hadn't peaked. Meanwhile, the National Weather Service was showing the remains of Sandy over west central Pennsylvania and continuing to drop precipitation in the Susquehanna Basin. Some of that precipitation, however, was coming in form of snow which wouldn't necessarily contribute to flooding in the short term.
By comparison, the river's peak flow after last year's storms was recorded Sept. 9, 2011, at nearly 10 times the Tuesday flow, or 600,000 cubic feet per second.
The Conowingo Dam generator report, recorded daily for the convenience of anglers, noted that the Fishermen's Park on the downriver side of the dam was closed because of the storm. Meanwhile, four of the dam's 52 flood gates were opened Tuesday. Flooding typically occurs along the low areas of Route 222 between the dam and Port Deposit when a dozen or more gates are opened.
Most of the flood advisories in Pennsylvania, as of Tuesday afternoon, were in the Delaware River basin rather than the Susquehanna basin.
Bryna Zumer contributed to this story.Copyright © 2015, The Baltimore Sun