Effect of Toston Dam on Upstream Ice Conditions

• Main Author: Ashton, George D.
• Other Authors: COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
• Format: Text
• Language: English
• Published: 1989
• Subjects: Snow; Ice and Permafrost; Civil Engineering; *DAMS; *ICE; THEORY; WINTER; LEVEL(QUANTITY); JAMMING; ELECTRIC POWER; RIVERS; ELEVATION; FLOODING; SUMMER; RESERVOIRS; RAILROAD TRACKS; MISSOURI RIVER; MONTANA; IRRIGATION SYSTEMS; HYDROELECTRICITY; WATER; COMPUTER PROGRAMS; THICKNESS; RIVER ICE; TOSTON DAM; ICE JAM THEORY; HEC-2 COMPUTER PROGRAM; WATER LEVEL; Burlington; Crow Creek; Ice; permafrost
• Online Access: http://www.dtic.mil/docs/citations/ADA210119; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA210119

A study was conducted to evaluate the effect of raising the winter- period reservoir level at Toston Dam on the Missouri River to an elevation of 3952.6 ft ASL. At present the dam is operated as an overflow dam with crest elevation of 3941.6 ft during the winter. In summer, flashboards are installed to maintain reservoir levels in the range 3949 to 3952 ft and water is diverted for irrigation. A proposal to install hydropower at the dam would require replacement of the existing flashboard system and maintenance of a higher water level at the dam during the winter. There is concern with the possible effects on the Crow Creek pumping plant located about 2 miles upstream, with possible ice-related flooding of the Burlington Northern railroad track along the east side of the reservoir, with effects of ice on existing islands in the reservoir, etc. The analysis used the HEC-2 program with the ice option to estimate water levels under present and future raised dam elevations. Ice thicknesses were estimated using a trial-and-error procedure based on existing ice jam theory. Results of the analysis were validated using field observations from two winters. Keywords: Montana; River ice.