From the record
“The China Ditch in Douglas County, in the U.S. state of Oregon, was a 30-mile (48 km) canal built in part by Chinese laborers to supply water for the hydraulic mining of gold. The Myrtle Creek Consolidated Hydraulic Gold Mining and Manufacturing Company began purchasing land for the ditch in 1890 and was bankrupt by 1894.”
Wikipedia article China Ditch, CC BY-SA 4.0.
One of 47 National Register listings published here for Douglas County · listed in 1991 · category: Structure.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service