Beginning around 1870, Schuylkill County mines processing coal for the industrial revolution dumped culm, or waste, into huge piles in the valleys of the Schuylkill River's tributaries, and before regulations required containment, fine anthracite and silt washed downstream. Later, waste from washing and sizing coal was sluiced directly into the tributaries. By 1945, coal and silt discharged into the river was estimated at 3 million cubic yards per year, and before dredging began, 30 million cubic yards of culm had accumulated, clogging the main channel, filling dams, increasing flooding, fouling the water, and spreading black sediment over low lands during spring floods, making the Schuylkill River known as the dirtiest river in the state. In the 1940s and 50s, federal and state agencies funded a $55-million desilting project that over five years demolished five old canal dams, built 27 impounding basins, and constructed three desilting basins near new dams at Kernsville, Augurn, and Tamaqua. Dredged culm was transferred into these basins to dewater over five years, while river edges were trimmed to gentle slopes and undergrowth was removed for 40 feet on both sides to improve water movement. Although the initial dredging ended more than 50 years ago, active facilities at Kernsville, Auburn, and Tamaqua still remove about 100,000 tons of culm annually. At Felix Dam, the maintenance building, fenced power area, spud pole, dredge slip, and winch were part of removing culm from the pool behind the newer dam. High-voltage transformers and switching gear powered the dredge's electrical cutting head and pumps; the cutting head could clear culm and silt to a depth of 27 feet, while spud poles at the stern pivoted it along the river bottom and moved the dredge forward and backward. Suction pumps could move material about one mile to a basin, and booster pumps could carry it three more miles if needed. The Felix pool was dredged in 1950 and again in 1951 by the dredger "Montgomery."