CINCINNATI -- Just west of Downtown, sandwiched between two railroad bridges, there's a stone arch built more than 150 years ago.
Jeff Agricola is fairly certain the arch carried an aqueduct for the old Whitewater Canal system, linking the Whitewater River to Downtown. The Mill Creek flows underneath, meaning the arch carried water above water until it was was abandoned in the mid-1800s.
Few but the most intrepid urban explorers ever see it. On Saturday, thousands of people heading down the Ohio River for Paddlefest can go under the arch and get up close with other parts of early Cincinnati history, on a tour of the lower Mill Creek.
People set out from Schmidt Recreation Center on Aug. 6, 2016 for last year's Paddlefest. (Photo by Joe Simon | WCPO contributor)
The creek used to be Cincinnati's open-pit sewer, a notorious river of poo. But you'd never think of it as a sewage ditch if you paddled it today. Decades of cleanup work from thousands of volunteers have started to turn it around. There's still some waste, but also lots of wildlife.
This is the second year for the Mill Creek Mile -- a half-mile up, half-mile back -- thanks to Paddlefest's new route. The 9-mile event course goes from Schmidt Recreation Complex in the East End to Gilday Riverside Park in the city's Riverside neighborhood, taking participants right past the mouth of the Mill Creek.
Agricola is a member of the Mill Creek Yacht Club, a group that's canoed 26 of the stream's 28 miles. The yacht club will have volunteers in the water and on land for Saturday's tours. Members also placing banners at the creek's historic structures for people who want a self-guided experience.
"It has a powerful sense of place," yacht club member Bruce Koehler said.
RELATED: A trip down the Cincinnati region's notorious river of poo
The lower stretch of the Mill Creek is packed with infrastructure: In a half-mile stretch, paddlers will go under seven bridges -- four railroad bridges, plus the Sixth Street, Eighth Street and Gest Street viaducts. For some perspective, there's the same number of bridges along Paddlefest's main 9-mile course.
Gest Street, at the northern end of the half-mile tour, has a relatively new bridge deck. But Agricola said the abutments date to the 1840s or 1850s.
"You're talking about very early urban sprawl," Agricola said. "Obviously, they had the need to get to the west side of the Mill Creek Valley."
The span with the stone arch has a bridge from 1918 to the north, and 1920 to the south. The Cincinnati-Whitewater Canal was a spur off the main canal in Indiana, to bring commerce to and from the city. The canal on top would have been made of wood.
Agricola said the Indianapolis and Cincinnati Railroad bought the right-of-way in 1862, after the canal company went bankrupt.
"Then the railroad came through added to one side -- slapped a concrete bridge immediately up against the stone arch with the same opening," Koehler said. "They did it on the opposite side two years later."
Paddlers who opt for the Mill Creek tour also will pass through the Metropolitan Sewer District's Barrier Dam and by the pump house. The city built the dam after the Great Flood of 1937, when the Ohio River maxed out at 79.9 feet and drove 100,000 people from their homes. Fifteen percent of Cincinnati was covered in water. Eight people lost their lives.
Construction started in 1941 but was postponed because of World War II. The dam was completed in 1948.
"It protects 4.6 square miles of Cincinnati from the Ohio River floodwaters, and it'll protect those 4.6 square miles to a flood stage of 83 feet," Agricola said.
The dam's opening to the Mill Creek is closed when the Ohio River begins to flood, with 14 metal bulkheads weighing 11,000 pounds each. Pumps lift water out of the Mill Creek and dump it back into the Ohio.
"When all pumps are operating at full capacity, which rarely happens, they can move 9 billion gallons a day," Agricola said -- which he put at about 30 Riverfront Stadiums' worth of water.
About 2,000 people were at last year's Paddlefest, and the yacht club estimates about 600 came up the Mill Creek. They're hoping for even more this year.
Kayaks, canoes -- all boat types are welcome, Koehler said: The water is deep, and there's no logjam blocking the path.
Volunteers will be available at the Mill Creek from 7 a.m. to noon.
Online registration for Paddlefest has closed, but there are three chances to register in person:
Thursday, Aug. 3, 4-8 p.m.
Roads Rivers and Trails in MilfordFriday, Aug. 4, 4-8 p.m.
Paddlers, Friends, and Sponsors Party at Schmidt Recreation ComplexSaturday, Aug. 5, 6-8:30 a.m.
Paddlefest put-in at Schmidt Recreation Complex
