For over ten years, Stetson has provided technical support for the water rights claims of the Gros Ventre and Assiniboine Tribes living on the Fort Belknap Indian Reservation in central Montana. Stetson has quantified reserved water rights claims on the Milk River and Lower Peoples Creek, including preparation of conceptual irrigation water development plans and determination of Practicably Irrigable Acreage (PIA) requirements for the Reservation. Stetson has quantified available natural flow, and has developed a reservoir and irrigation operations model to simulate scenarios within the irrigation development plan. Stetson prepared feasibility-level designs and cost estimates for three off-stream reservoirs and for the enlargement of Fresno Reservoir located on the Milk River. An integral part of the study was a feasibility-level analysis of about 60 pump stations with capacities ranging from 125 to 3,800 gpm and main river pump stations with capacity ranging from 50 to 520 cfs. Design and cost estimates for water delivery pipelines ranging in size from 6 to 48 inches in diameter were prepared. The project also included the design of over 3,000 acres of wetlands and wildlife habitat for migrating birds.

Tasks completed for this project include:

  • Collection and analysis of climate data for weather stations located in the vicinity of the Reservation and a review of existing surface water and groundwater data from state and federal agencies.
  • Land classification for about 200,000 acres, using aerial photograph interpretation to establish land use for about 50,000 acres.
  • Irrigation system and water delivery facilities design and cost estimates for about 40,000 future acres, including cropping pattern, diversion requirements, pump stations, canals, drip and sprinkler irrigation systems, pipelines, and drainage.
  • Development of a reservoir and water delivery system operations model with 16 reservoirs, using a 69-year period of record.
  • Evaluation of water quality for irrigation suitability.