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BRIEF
CHRONOLOGY OF ZOSEL DAM'S HISTORY
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| Zosel
dam constructed to provide a millpond for delivery of logs to the Zosel
Mill. No reference made to Canada or the International Joint Commission
(IJC). |
| Complaints
about high Osoyoos Lake levels result in Washington State (WA) asking the
IJC to hold hearings. This done, they appoint a Board of Engineers (B of
E) to investigate the hydraulics of the outlet of Osoyoos Lake. |
| The
B of E determines that under some conditions, Zosel Dam is causing high
lake levels. The IJC order Zosel to increase the capacity of the dam so
that it can pass 2500 ft3/sec with the millpond level not exceeding
elevation 911 ft. No mention is made of Osoyoos Lake levels. An International
Osoyoos Lake Board of Control is established to monitor the operation. |
| Modifications
to Zosel Dam completed to the IJC's satisfaction. |
| Zosel
sawmill stops using the millpond to deliver logs. |
| Partial
collapse of Zosel dam (due to age/maintenance) necessitates emergency repairs
by Washington and the US Army Corps of Engineers (USACE). |
| Another
failure of the dam occurs, again repaired. |
The
IJC ask the USACE to report on the condition of Zosel Dam. Their report
expresses grave concern about the dam's structural integrity and indicates
that, were it to collapse, Osoyoos Lake could fall as low as 905 ft.
Although there has been no reference from either British Columbia
(BC) or WA, the IJC calls hearings to discuss the condition of Zosel
Dam. During these hearings, BC and WA agree that there is a basis for a
cooperative approach and tell the Commission that they will return within
a year with a joint reference. The IJC asks the USACE to draw up plans for
a replacement structure. |
| The
USACE produce a plan for a replacement structure almost a kilometre upstream
of the original dam. The cost estimate is for US$6.2 million. |
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BC and WA exchange
a document entitled British Columbia-Washington Cooperation Plan for
Osoyoos Lake Levels and Trans-Border Flows. This document which is
non-binding lays out target lake evelations and trans-border flows during
both normal and drought conditions once a new dam is built.
WA applies
to the IJC for permission to rebuild Zosel Dam much as outlined in the
USACE report with the BC-WA Cooperation Plan attached for reference
only.
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| The
IJC holds public hearings in both Oroville and Osoyoos to gather local input
to the proposed dam. |
| The
IJC issues an Order
of Approval for the construction of the dam. This details the required
capacity of the dam as 2500 cfs at an Osoyoos Lake elevation not exceeding
913 ft and the range of allowable lake levels under various conditions.
(This capacity is very similar to that required under the 1946 Order
of Approval as a millpond elevation of 911ft. at 2500 cfs implies an Osoyoos
Lake level of about 913ft.) |
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WA and BC agree
on a Memorandum of Understanding regarding the cost sharing of
the design and construction of the new facility. (The delay was due to
fiscal problems in both jurisdictions.)
Acres International
(Vancouver) is appointed as the consulting engineer. After detailed site
investigation and design they submit plans which show the dam moved downstream
(close to the original dam location), with a different gate design and
proposing a new solution to the Tonasket Creek fan problem from the proposed
by the USACE.
Because the
dam location is changed and because the original time limit for construction
of the dam would be exceeded, the IJC decides to hold further public hearings
in Oroville and Osoyoos. After these a Supplementary
Order of Approval is issued, approving the new design and location
and extending the completion date.
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| Construction
of the new dam begins. |
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Construction
essentially complete.
Drought conditions
are forecast on the Similkameen. After the water has been stored and the
lake raised to elevation 913, drought does not materialize and the stored
water is dumped in early August. This leads to discussions regarding how
best to lower water levels if drought declaration is rescinded.
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| Drought
forecast and occurs. Osoyoos Lake held above elevation 911.5 from May 6
through August 25, maximum 912.63 ft. |
| Drought
forecast and occurs. Osoyoos Lake above 911.5 from June 18 until September
30th, with a peak of 912.87 in mid-August. This is achieved by importing
water from the Similkameen through the old Okanagan-Tonasket Irrigation
District flume. Many complaints about high lake levels are received. |
| Drought
forecast and occurs. BC and WA agree
on a maximum Osoyoos Lake level of 912.5 with BC supplying the volume equivalent
of 6 inches on Osoyoos Lake out of Okanagan Lake when asked to do so by
WA. Not to be considered a precedent. |
| Drought
forecast and occurs. Same agreement
as '93 re 912.5 is agreed by BC and WA. |
| Drought
forecast but does not occur. |
| Drought
forecast and occurs. Similar agreement
between WA and BC to keep max level to 912.5. |
| * |
| x
R.
Y. McNeil 01/09/25
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