Bloede's Dam was a hydroelectric dam on the Patapsco River in Maryland. It was the first known instance of a submerged hydroelectric plant, where the power plant was actually housed under the spillway. It is also recognized as one of the earliest dams constructed of reinforced concrete. This area is now part of Patapsco Valley State Park Avalon Area. History and design The Patapsco Electric and Manufacturing company, of Ellicott City, brought fame to the Patapsco River corridor in 1906 when it constructed the world's first underwater hydroelectric plant to supply its electricity. The Dam is named for Victor Gustav Bloede (pronounced as Blerda), a German immigrant who founded of the Avalon Water Works in the same area, was its president at the time. Bloede hired electrical engineer Otto Wonder to oversee the development of this unique hydroelectric project near Gray's Mill on the Patapsco River. Construction was performed by the Emmerson Ferro-Conrete company of Boston. The dam itself was long, wide at the base and had a drop of . It was an Ambursen Hydraulic Construction Company (Boston type) reinforced concrete slab and buttress dam. The power plant technology and equipment were state of the art when it went into operation in 1907, with 34-inch Poole & Hunt Leffel Wheels and two 30-inch 500 hp horizontal Samson Turbines capable of an electromotive force of 11,000 volts. A 200 foot long fish ladder was constructed along the site. The arrangement made the facility the world's first underwater hydroelectric plant. In its original plan, the plant was meant as an independent competitor to the local electric companies, and supplied power to the surrounding towns of Illchester, Ellicott City and Catonsville many of which were outside of the utilities' service area. It replaced an earlier 300 hp plant purchased for $12,000 in 1900 two miles away at Gray's mills that employed a millrace with a bevel gear and rope drive. The $175,000 electric generation equipment was engaged on 28 November 1908 at 3:30pm by Victor Bloede's daughter, Miss Vida Bloede. Waffles were served to 500 dignitaries and guests from electric waffle makers. The newly formed Maryland Public Service Commission refused to grant Bloede a franchise to compete in electricity generation. Bloede claimed that Consolidated was attempting to force a sale because the company was charging less on street light contracts with Catonsville and Baltimore. In 1913, the plant was sold to Consolidated