The Upper Main Ditch is a section of the El Dorado Ditch built by mining interests to convey water to the Placerville area in the late 1800s. The ditch and water rights were sold to the Western States Gas and Electric Company in the early 1900s, primarily for hydroelectric power generation. A smaller portion of the ditch water was maintained for delivery to some agricultural users. Over time, EID took over the rights and responsibilities for delivery of non-power generating water to irrigation and domestic water users. In 1997, EID took responsibility for all water rights and the facilities along the original El Dorado Canal, known as FERC Project No. 184, which provides raw water to the Upper Main Ditch.