Ralph L. Parshall Collection

Ralph Leroy Parshall, engineer, contributed significantly to the field of irrigation engineering with the development of a flow-measuring device that became known as the Parshall flume and continues to be widely used. A Colorado native, Parshall was born in Golden on July 2, 1881. He received his B.S. in civil and irrigation engineering from Colorado Agricultural College (now Colorado State University) in 1904. During the summers of 1906 and 1907 he pursued graduate work at the University of Chicago. At Colorado Agricultural College, he was an instructor in physics and civil engineering between 1904 and 1909 and then assistant professor from 1909 to 1913. In 1913 he was appointed assistant engineer and director of irrigation investigations with the Division of Irrigation, Soil Conservation Service, U.S. Department of Agriculture, then housed at the college. In 1918 he became director of the program and served in that capacity until he retired in 1948 with the title of Senior Engineer. Even in retirement he continued as researcher, consultant, and sometimes lecturer at the college.

While Parshall's flume was his most notable work, he also investigated a number of irrigation-related problems. He designed and built various irrigation recording instruments and meters, such as those used in concert with the Parshall flume, and developed sand traps such as the vortex tube and riffle deflector. Parshall participated in surveys and planning for the Colorado-Big Thompson Project, and during the 1940s was survey supervisor for an investigation of snow measurement methods and work relating water content of snowpack to irrigation water supply.

Parshall was honored as a Life Member of the American Society of Civil Engineers, as well as a Life Member of the Colorado Society of Engineers. He was also honored with a lifetime achievement award from the Alumni Association of the Colorado Agricultural College in 1942. He received a special citation and medal from the U.S. Department of Agriculture at his retirement in 1948, and a gold medal award from the Colorado Engineering Council in 1949.

Parshall married Florence May Stuver in 1906 and had two sons: Maxwell and Deane. Ralph Parshall died in Fort Collins, Colorado, on December 29, 1959.

Maxwell Parshall was born in Colorado on March 11, 1907. He attended Colorado Agricultural College and the Massachusetts Institute of Technology, receiving his B.S. in chemistry from MIT in 1929. After graduation he worked in Colorado, first for the State Dairy Commission and later for the U.S. Department of Agriculture. In 1937 he began working at Colorado State College (now CSU) in Fort Collins, serving with the Civil Engineering Department and for a number of years heading the weather station there. He remained at the college for more than 30 years. Parshall died in Billings, Montana, on January 30, 1996.

Carl Rohwer, born in Nebraska in 1890 and graduated from Cornell in 1913, joined Ralph Parshall at the USDA in Fort Collins in 1914. The two worked together on many projects, studying evapotranspiration, water flow measurement, water well designs, and ditch seepage. Rohwer became the leader of the research group after Parshall retired, until his own retirement in 1956. He died in 1958.