Osoyoos - Annual Report 1995

ANNUAL REPORT
to the
INTERNATIONAL JOINT COMMISSION
from the
INTERNATIONAL OSOYOOS LAKE BOARD OF CONTROL
for
CALENDAR YEAR 1995

ACTIVITIES OF THE BOARD

The International Osoyoos Lake Board of Control was established on February 12, 1986, by the International Joint Commission to carry out the provisions of the Commission Order of Approval dated December 9, 1982, and the Supplementary Order of Approval dated October 17, 1985.

The Board met in Osoyoos, B.C., on September 28, 1995, and also held a public meeting that day.
OPERATION AND MAINTENANCE OF ZOSEL DAM

a. Osoyoos Lake Elevations

Levels of Osoyoos Lake were controlled by Zosel Dam throughout the year in accordance with criteria specified in the Order of Approval. The authorized range of normal operating elevations, 909.0 to 911.5 feet, is shown by the blue area in appendix I. The grey area on appendix I shows the authorized range of elevations, 910.5 to 913.0 feet, that may be used to provide additional storage from April 1 to October 31 if drought conditions are declared by the Board. Drought conditions did not occur and criteria for normal operation applied during the year.

Recorded lake elevations for water years 1992-95 are shown on appendix I.

Data on Osoyoos Lake levels and relevant river flows are summarized in appendix II.

b. Drought Operation

Drought conditions did not occur during the year.

c. Zosel Dam

The Oroville-Tonasket Irrigation District operated Zosel Dam under the authority of the State of Washington, Department of Ecology. Levels on Osoyoos Lake were maintained for the year in accordance with the Commission's Orders of Approval.
IMPROVEMENTS TO THE OKANOGAN RIVER CHANNEL

The Board has obtained confirmation from the State regarding the capacities of the Okanogan River Channel. Water is able to be moved out of the lake, through the channel, and past the dam at a rate of 2,500 cubic feet per second with the lake at elevation 913.0 and no appreciable backwater effect from the Similkameen River.

The detailed results of the 1993 model runs will appear in the State's annual Zosel Dam Report to the Board of Control.

The maximum instantaneous flow on the Okanogan River occurred on May 20 at Oroville and was 2,430 cubic feet per second. Osoyoos Lake was at elevation 911.97 feet, and the Okanogan River at Oroville was in backwater from the Similkameen River on that day.

The maximum elevation on Osoyoos Lake occurred on May 20 at 912.03 feet, and the mean daily discharge was 2,300 cubic feet per second at Okanogan River at Oroville for that day.

Appendix 8 - Osoyoos Lake Elevations

Appendix II - Osoyoos Lake Levels, Inflows, and Outflows


ANNUAL REPORT to the INTERNATIONAL JOINT COMMISSION from the INTERNATIONAL OSOYOOS LAKE BOARD OF CONTROL for CALENDAR YEAR 1995 ACTIVITIES OF THE BOARD The International Osoyoos Lake Board of Control was established on February 12, 1986, by the International Joint Commission to carry out the provisions of the Commission Order of Approval dated December 9, 1982, and the Supplementary Order of Approval dated October 17, 1985. The Board met in Osoyoos, B.C., on September 28, 1995, and also held a public meeting that day. OPERATION AND MAINTENANCE OF ZOSEL DAM a. Osoyoos Lake Elevations Levels of Osoyoos Lake were controlled by Zosel Dam throughout the year in accordance with criteria specified in the Order of Approval. The authorized range of normal operating elevations, 909.0 to 911.5 feet, is shown by the blue area in appendix I. The grey area on appendix I shows the authorized range of elevations, 910.5 to 913.0 feet, that may be used to provide additional storage from April 1 to October 31 if drought conditions are declared by the Board. Drought conditions did not occur and criteria for normal operation applied during the year. Recorded lake elevations for water years 1992-95 are shown on appendix I. Data on Osoyoos Lake levels and relevant river flows are summarized in appendix II. b. Drought Operation Drought conditions did not occur during the year. c. Zosel Dam The Oroville-Tonasket Irrigation District operated Zosel Dam under the authority of the State of Washington, Department of Ecology. Levels on Osoyoos Lake were maintained for the year in accordance with the Commission's Orders of Approval. IMPROVEMENTS TO THE OKANOGAN RIVER CHANNEL The Board has obtained confirmation from the State regarding the capacities of the Okanogan River Channel. Water is able to be moved out of the lake, through the channel, and past the dam at a rate of 2,500 cubic feet per second with the lake at elevation 913.0 and no appreciable backwater effect from the Similkameen River. The detailed results of the 1993 model runs will appear in the State's annual Zosel Dam Report to the Board of Control. The maximum instantaneous flow on the Okanogan River occurred on May 20 at Oroville and was 2,430 cubic feet per second. Osoyoos Lake was at elevation 911.97 feet, and the Okanogan River at Oroville was in backwater from the Similkameen River on that day. The maximum elevation on Osoyoos Lake occurred on May 20 at 912.03 feet, and the mean daily discharge was 2,300 cubic feet per second at Okanogan River at Oroville for that day.