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Bathymetric Map, Surface Area, and Stage-Capacity for the U.S. Part of Koocanusa Reservoir, Lincoln County, Montana, 2016–18

Scientific Investigations Map 3485
Prepared in cooperation with the U.S. Army Corps of Engineers
By:  and 
https://doi.org/10.3133/sim3485

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Abstract

The U.S. Geological Survey and U.S. Army Corps of Engineers collected high-resolution multibeam sonar data during 2016–18 to compute stage-area and stage-capacity tables for the U.S. part of Koocanusa Reservoir in Lincoln County, northwestern Montana. Koocanusa Reservoir is a transboundary reservoir extending about 48 miles from Libby Dam upstream to the U.S. international boundary with Canada and another 42 miles within Canada to near Wardner, British Columbia. The upstream extent of the reservoir within Canada, where much of the sedimentation was previously documented, was not included in this study. Previously developed stage-area and stage-capacity tables were developed for the entire reservoir and could not be directly compared to the stage-area and stage-capacity tables from this study. Two discrete stage-area and stage-capacity values from the original survey (unknown survey date prior to 1980) were available for parts of the reservoir within the United States at the normal full-pool and normal minimum-pool elevations (2,459 and 2,287 U.S. survey feet above the National Geodetic Vertical Datum of 1929, respectively). At the normal full-pool elevation, the stage-area relation resulted in a 0.06-percent increase in surface-water acreage. Conversely, a 0.03-percent decrease in storage capacity at the normal full-pool elevation occurred. At the normal-minimum-pool elevation, the stage-area relation showed a 1.21-percent decrease in surface water from 14,487 to 14,314 acres. The usable storage capacity, defined as the volume of water between the normal full-pool and normal minimum-pool elevations, decreased by 0.39 percent (15,353 acre-feet). Results from this study indicate that a relatively minimal amount of sedimentation has occurred since initial filling in Koocanusa Reservoir for parts of the reservoir within the United States. Updated stage-area and stage-capacity tables for the entire reservoir will require additional bathymetric and topographic surveys for the parts of Koocanusa Reservoir within Canada.

Suggested Citation

Fosness, R.L., and Dudunake, T.J., 2022, Bathymetric map, surface  area, and stage-capacity for the U.S. part of Lake Koocanusa, Lincoln County, Montana,  2016–18: U.S. Geological Survey Scientific Investigations Map 3485, scale 1:100,000,  https://doi.org/10.3133/sim3485.

ISSN: 2329-132X (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Methods
  • Stage-Area and Stage-Capacity Tables
  • Summary
  • Acknowledgments
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Bathymetric map, surface  area, and stage-capacity for the U.S. part of Lake Koocanusa, Lincoln County, Montana,  2016–18
Series title Scientific Investigations Map
Series number 3485
DOI 10.3133/sim3485
Year Published 2022
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Idaho Water Science Center
Description 1 Plate: 30.00 × 35.00 inches; Data Release
Country United States
State Montana
County Lincoln County
Other Geospatial Koocanusa Reservoir
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details