'

Coquitlam Lake supplying the remainder. Hydrology studies carried out by
Kerr, Wood Leidal Associates Ltd., as part of the Comprehensive Regional
Water Supply Study have determined the population that can be supplied with
water fro“feach of the three sources. This "Population Support Capacity" or

PSC, has been derived for various frequencies of drought, both with sources
as presently developed and with additional storage capacity.

i
The results indicate that for the 100-year drought case, Capilano and

Seymour combined have a PSC of about 1.2 million people. Coquitlam has a
PSC of about 1.8 million people if used primarily for domestic supply with
power generation taking a secondary role. The storage volume at Coquitlam
Lake is sufficient to optimize the annual inflew for domestic supply while

the Capilano and Seymour supplies are heavily storage-constrained.

The reason for proposing a Water Shortage Response Plan is mainly to address
‘concerns over storage depletion that occurred in the summer of 1990 in
Capilano and Seymour Lakes. The combined population served from these two
reservoirs is approaching the 1.2 million PSC and this fact, coupled with
low natural inflow to the lakes last summer, resulted in the lakes being
drawn down to record low levels in July and August. This gave rise to
concerns that actual shortages and inability to supply could result if the
drought persisted into the late Fall. Fortunately, enough rain fell to
avert a crisis, but it was felt that a better means of communicating
information about the state of water reserves and their significance to:
District members was needed. The proposed Water Shortage Response Plan is
intended to meet this need, recognizing that it will require modification as

experience is gained with its application. Given the fact that much of the
region's water demand arises from unmetered residential use, it is difficult

to ascertain the impact of various conservation strategies.

Description of Plan

The. proposed plan can be best described in two related parts:

:
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1. Communication of Supply/Demand Status

2. - Recommendation for Response

1. Communication of Supply/Demand Status