Osoyoos Lake Plan of Study

Plan of Study for Renewal of the International Joint Commission’s Osoyoos Lake Orders August 11, 2006 Prepared by Glenfir Resources [page intentionally blank] Final Plan of Study for Renewal of the International Joint Commission’s Osoyoos Lake Orders August 11, 2006 Prepared by Glenfir Resources 2 DISCLAIMERS This Plan was prepared by Glenfir Resources, an independent contracting proprietorship associated with neither the International Joint Commission (the Commission) nor the Governments of Canada or the United States. The report contents do not necessarily reflect the views of the Commission or the governments of either country and do not commit the Commission in any fashion. Glenfir Resources cannot accept responsibility for the performance or actions of any of the companies cited as possible Study Agents in this Plan of Study. ACKNOWLEDGEMENTS The authors would like to thank the members of the Osoyoos Board of Control and staff of the International Joint Commission for their guidance and assistance. We would also like to thank the many agencies, organizations and individuals who provided information and made suggestions in regard to this Plan (see Appendix II). TABLE OF CONTENTS EXECUTIVE SUMMARY .............................................................................................. 5 INTRODUCTION ............................................................................................................ 8 DESCRIPTION OF THE BASIN..................................................................................... 9 Historical Context ................................................................................................. 9 Physiography ........................................................................................................ 9 Climate................................................................................................................ 10 Demographics ..................................................................................................... 10 Land and Resource Management ....................................................................... 10 Ecological Significance ...................................................................................... 12 Changes since the 1985 Orders of Approval were issued .................................. 13 SYSTEM HYDROLOGY AND WATER MANAGEMENT........................................ 14 Geology .............................................................................................................. 14 Groundwater ...................................................................................................... 15 Surface Water ..................................................................................................... 15 Uncontrollable Factors Regulating Lake Levels ................................................ 17 Impacts to System Hydrology ............................................................................ 19 Orders of Approval ............................................................................................ 21 Compliance with the Orders .............................................................................. 23 METHODS FOR PREPARING THE PLAN OF STUDY ............................................ 24 Information Sources ........................................................................................... 24 Identification, Selection & Prioritization of Issues and Studies ........................ 24 Selection of Study Agents .................................................................................. 25 Choice of Timelines ........................................................................................... 25 Cost Estimation .................................................................................................. 25 KEY ISSUES AND RECOMMENDED STUDIES ...................................................... 26 Study 1 – An Assessment of the Most Suitable Water Levels for Osoyoos Lake During Drought Years ....................................................... 26 Study 2 – An Evaluation of the Criteria Used to Declare Drought ................... 33 Study 3 - A Review of the Dates for Switching Between Summer and Winter Operation ....................................................................... 37 Study 4 – An Investigation of the Effects, if any, of Water Regulation on Water Quality in Osoyoos Lake..................................................................... 41 Study 5 – An Investigation of Methods for Including Ecosystem Requirements in Orders of Approval .............................................................. 45 Study 6- An Investigation of Methods for Including Climate Change Information in Orders of Approval .................................................................. 50 Study 7 –A Demonstration of the Factors That Govern Lake Levels during Floods .............................................................................. 54 4 Study 8 - An Assessment of the Methods Used to Monitor Flow Capacity in the Okanogan River ..................................................................................... 59 IMPLEMENTATION OF STUDIES ............................................................................ 63 PUBLIC INVOLVEMENT AND PUBLIC RESPONSE .............................................. 65 5 EXECUTIVE SUMMARY Zosel Dam stores water in Osoyoos Lake for irrigation, domestic, recreation, and fisheries uses. The dam is operated to maintain certain lake levels that are prescribed by the International Joint Commission (Commission) in “Orders of Approval”. These orders terminate in 2013. At that time Commissioners will need to know whether to renew or modify them. This “Plan of Study,” explores issues associated with the present Orders and recommends investigations that will inform the Commission about these issues. Included in this plan are descriptions of how the studies should be carried out, who should carry them out, estimated costs, and recommended timelines. To set the stage for the studies the plan describes both the Canadian Okanagan River basin and the U.S. Okanogan River basin. The Similkameen River basin is also included because it frequently affects outflows from the system. The review of the basins shows that many changes have occurred in the 18 years since the Zosel Dam was reconstructed and the present Orders took effect. The population has grown to about 355,000 people, water demands have increased, waterfront properties have increased greatly in value and climate change has altered the valley’s hydrology. All these factors should be considered when the Orders are reissued. The first step in preparing the Plan of Study was to scope out the issues connected with the present Orders of Approval. This was done by notifying 492 groups or individuals, directly contacting about 90 parties known to have interests relating to Osoyoos Lake, and making presentations at two public meetings, a meeting of the international Bilateral Okanagan Basin Working Group and a meeting of the Okanagan Shuswap Land and Resource Management Plan Implementation Committee. In addition we looked for issues as we reviewed over 150 technical reports, meeting minutes, and government files. Our research and consultations indicated that the biggest single issue directly linked to the present IJC Orders is high water levels stored through the summer during drought years. The present orders allow the lake to be raised to 913.0 feet above sea level throughout the summer so that water will be available for irrigation and fisheries in the fall. This level reportedly exposes lakeside properties to erosion from boat wakes and waves caused by summer winds, soaks camping areas, covers beaches, and inundates hayfields. However, a reduction of only 6 inches reportedly solves these problems and appears to be acceptable to most stakeholders. To further investigate this issue we propose a study that will define the future water demand, examine several variations of the lake levels that would meet the demand, look at the impacts involved, and recommend the best options for lake levels during drought conditions. Not only have people been impacted by the high water during droughts but they have also noticed that drought conditions have been declared in about half of all years since the new Zosel Dam was completed in 1988. As a result, many question the suitability of the criteria that are being used to declare a drought. The criteria are based on the amount of 6 water in Okanagan Lake, the expected summer inflow to Okanagan Lake and the expected inflow to the Similkameen River. These are logical criteria but they are employed in an all or nothing fashion that fails to take into account the severity of drought. A study is recommended to determine ways of setting water levels based upon the degree of drought. Osoyoos Lake levels are regulated differently in the winter than the summer. The dates of switching between summer and winter schedules have been criticized for not conforming to the natural hydrograph. Some complainants say that filling the lake early removes any storage capacity that would otherwise be available to absorb flood waters. Others say that the hydrograph should be kept as natural as possible to benefit the ecosystem. We propose a study that would employ modeling techniques to examine the pros and cons of various scheduling dates. Water quality in Osoyoos Lake is a major worry for many stakeholders since the economy of the area depends upon beach

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