William Martin, manager of Tredyffrin Township, one of the towns that owns the ruptured pipe, said the pipe was repaired by 5 p.m. Wednesday, and there was no more overflow into the creek.
Full repairs to the road were expected by Thursday afternoon.
He said officials would not know the cause until a detailed analysis is done.
"Clearly, we need to evaluate the whole line," he said. Installed in the early 1970s, it is a 30-inch concrete pipe with steel reinforcing bands. The line operation is shared with all the members of the Valley Creek Trunk Sewer which includes Tredyffrin, Easttown, East Whiteland, Malvern Borough, Willistown and Valley Forge Sewer Authority.
Throughout the region - and the nation - water officials are dealing with an aging infrastructure that will cost billions of dollars to upgrade.
But taxpayers and officials intent on reelection often balk at such projects, preferring more visible, above-ground ventures - until a major burst occurs.
Valley Creek flows into the Schuylkill not far from where the spill occurred, but drinking-water intakes downstream in Norristown and Philadelphia remained unaffected by the spill, officials said.
Not so the creek itself.
Downstream of the pumping station, as it goes through the park, it hugs the winding Route 252 between a white covered bridge at Yellow Springs Road and Route 23. A hiking trail also runs along it.
But while the road was closed, the park's chief ranger, Greg Tinkham, said the trail remained open.
"At this point, as far as trails, it's not a huge impact," he said of the spill, adding, "Obviously, the creek's an issue. I wouldn't recommend anyone going in the creek."
He said the park's other trails are open and unaffected.
Although there was no noticeable fish kill at the time, members of the Valley Forge Chapter of Trout Unlimited, who were walking the edges of the stream Wednesday, were worried.
They said it may take several days for fish to die, or dead fish may already be in deeper parts of the stream, hidden by the now-turbid water.
Valley Creek is known for the exceptional quality of its brown trout fishery, said John Dettrey, the group's secretary. Anglers come from out-of-state to fish in its scenic pools, bordered by mature sycamore trees.
Ironically, he said, the fishery owes much of its success to an earlier pollution incident, when PCBs drained from the Paoli Rail Yard, later designated a Superfund site.
PCBs don't kill the fish, but the chemical accumulates in their tissue, and humans who eat the fish can be harmed.
So Valley Creek became a catch-and-release fishery, and the trout grew. Some now are 28 inches, Dettrey said.
"A lot of people will tell you, it's one of the best things that ever happened . . . if you take the view that trout populations benefited by people not coming to remove them," he said.
Drexel University's Charles Haas, the LD Betz Professor of Environmental Engineering, said it was unlikely that Philadelphia's drinking-water intakes would be affected because the wastewater would be so diluted by the time it flowed that far downstream.
But water officials remained alert.
A "flow model" from an early warning system estimated the plume from the spill reached Philadelphia's intakes at Queen Lane and Belmont between 3 and 4 a.m. on Wednesday.
Officials increased the frequency of raw-water analyses at both plants and did not see any impacts from the spill, but both plants increased chlorination Tuesday evening as a precaution, said spokeswoman Joanne Dahme.
Pennsylvania American Water, which owns the Norristown plant, also upped its chlorination, both as a precaution and because Wednesday's rainfall increased the turbidity of the river water, said spokesman Terry Maenza.
At the pipe break, workers from many companies plus consultants and regulatory officials worked throughout the day.
Trucks from Aqua America, a private water company, sucked about 200,000 gallons of sewage out of the creek and transported it to a nearby treatment plant run by the Valley Forge Sewer Authority, where the broken pipelines would have deposited it.