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Ralph L. Parshall Collection

Identifier: WRLP

Scope and Contents

The Ralph L. Parshall Collection consists of documents dated 1888 to 1992, with the bulk falling from 1921 to 1961. While Parshall is the focus of the collection, there is relatively little personal correspondence and few of his personal files are contained here. The collection does include Parshall's patent on the water stage recording instruments used with his flume, awards he received, publications, copies of talks he presented on KOA radio in Denver, and data and multiple drafts from his study of seepage in the South Platte Basin. Additionally, media types include photographs of Parshall, a number of lantern slides depicting flumes, weirs, plans, graphs, and tables, and a 16mm film on snow measurement. Included as well are some materials related to Carl Rohwer, who joined the Division of Irrigation in the U.S. Department of Agriculture in 1914. These mostly concern a project in the San Luis Valley. The collection also contains some files from Maxwell Parshall, including correspondence, data, a tape, and a transcript of the tape.


  • Creation: 1888-1992
  • Creation: Majority of material found within 1921-1961


Restrictions on Access

There are no access restrictions on this collection.

Restrictions on Use

Not all of the material in the collection is in the public domain. Researchers are responsible for addressing copyright issues.


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.


13.5 linear feet (7 document boxes, 3 flat boxes, 2 lantern slide boxes, 2 artifact boxes, 1 film box, 1 flat file)

Language of Materials



Ralph Parshall contributed significantly to the field of irrigation engineering with the development of a flow-measuring device that became commonly known as the Parshall flume and continues to be widely used. Materials in the collection include Parshall's patent on his "Venturi flume water stage recording instruments," awards that Parshall received, publications, copies of talks he presented on KOA radio in Denver, and a number of lantern slides depicting flumes, weirs, plans, and various graphs and tables. The collection also contains some materials related to Parshall's son, Maxwell Parshall, as well as to Carl Rohwer, a colleague in the Division of Irrigation at the U.S. Department of Agriculture. A portion of the collection is digitized and online.


The collection consists of 4 series in 15 boxes and 11 oversize folders:

Series 1: Papers, 1909-1992 and undated

Series 2: Publications, 1902-1962 and undated

Subseries 2.1: Publications by Parshall, 1921-1961

Subseries 2.2: Publications by others, 1902-1962 and undated

Series 3: Visual and audio materials, 1888-1992 and undated

Subseries 3.1: Photographic materials, 1888-1992 and undated

Subseries 3.2: Other materials, 1937-1940s and 1978

Series 4: Artifacts, 1901-1964 and undated


The Ralph L. Parshall Collection was acquired from various sources over time, with one addition received from Robert Ward on July 23, 2003. This included books, certificates, letters, photographs, and slides. The addition of the current meters was received from Everett Richardson on January 6, 2011. Additional materials, including drafts, drawings, photographs, publications, and clippings, were discovered at the Engineering Research Center and transferred to the Archive in November 2011. Letters sent by Parshall to the Elliot family were donated by Judy Elliot Riggenbach in June 2017. An artifact associated with Max Parshall was transferred from the Irrigation Photograph Collection in July 2017. The watercolor painting was donated by Kaye Shedlock and Rick Hasbrouck in February 2024.

Online Materials

Some materials have been scanned and are available through the Colorado State University Libraries website. In the electronic version of this document, direct links appear in context. Note that not all links are to the exact documents in this collection, but scans from other sources.

Related Collections

The Water Resources Archive contains the Irrigation Research Papers, which documents extensively the research of the Irrigation Investigations Unit of the U.S. Department of Agriculture in Fort Collins, Colorado, including Ralph Parshall's work on the Parshall flume. The Water Oral Histories Collection contains a 1986 tape recording by Maxwell Parshall, in which he describes work he did for the Water Supply and Storage Company and Colorado State University.

Separated Collections

The following item was transferred to the Groundwater Data Collection: Quadrangle sheets. Northeastern Colorado. Colorado Water Conservation Board. 1939.

The following materials were transferred to the Papers of Louis G. Carpenter: Lantern slides Zola Dam. 1892.

The materials found at the Engineering Research Center included documents related to Ralph Parshall, Maxwell Parshall, and Carl Rohwer, all added to this collection based on its existing contents. Materials found at the same time related to Louis Carpenter were transferred to that collection; those related to William Code were transferred to the Groundwater Data Collection. If associations were unclear, materials were kept in this collection.


The initial processing of the collection was completed in February 2005. Materials were placed in acid-free folders and metal fasteners were removed. Newspaper clippings were inserted between sheets of acid-free paper. Framed certificates and letters were removed from the frames. Loose photographs and negatives were separated to Series 3 and inserted in archival sleeves, envelopes, or folders. The film reel was housed in its own archival box, as was the cassette tape. Some publications were removed and added to Archives and Special Collections. The current meters were incorporated in October 2011. The materials found at the Engineering Research Center were incorporated in December 2012. Materials received in 2017 were incorporated in July 2017. The painting received in February 2024 was incorporated the same month.

Inventory Note

Note: Title information supplied by the archivist is bracketed. Estimated pagination is preceded by an "e." Two identical copies of the same item are indicated by the phrase "2 copies" at the end of the entry, following the number of pages of each copy. Authored articles, books, and studies are listed in bibliographic form.

Guide to the Ralph L. Parshall Collection
Edited Full Draft
Prepared by Holley R. Lange; revised by Patricia J. Rettig
Copyright 2017
Language of description
Script of description
Language of description note
Finding aid written in English.

Repository Details

Part of the CSU Libraries Archives & Special Collections Repository

Fort Collins Colorado 80523-1019 USA