Water Stewardship Information Sources

Citation Aquarius Research and Development. 2010. Skookum Creek Power Project - Hydrological Analysis. Prepared for ROR Power.
Organization ROR Power
URL http://squamish.cc/extranet/Planning/Referrals/Skookum%20Clean%20Energy%20Project/EXHIBITS/Ex%20%2010.%20Hydrological%20Analysis/Hydrological%20Analysis.pdf
Abstract/Description or Keywords A small hydropower “run‐of‐river” project is proposed on Skookum Creek in the Mamquam River Valley.  In
order to estimate water availability for environmental and energy analysis, a field program was initiated in
Dec 2003 at Skookum Creek.  This report presents the methods used in this program and results of the
program to date, with subsequent regression of these short‐term records to long‐term regional records in order
to estimate long‐term runoff volumes and patterns for the Skookum Creek Power Project.   The WSC stations
on the Cheakamus River to the north and on the Stave River to the east of the proposed project were used as
the primary regional stations.  The results of this analysis for the proposed intake and powerhouse locations
are shown in Table 1‐1.  The MAD at the powerhouse/gauge location is estimated to be 6.37 m³/s ± 7.1% at 1 σ
(67% confidence, or 14.2% at 2σ or 95% confidence).  Approximately 70% of this uncertainty is attributable to
hydrometric uncertainty, and only 30% is attributable to the extrapolation to long‐term patterns. Much of the
uncertainty in this estimate is due to large storm events that do not affect energy production estimates. For this
lower range of flows, a second uncertainty estimate is provide for flow less than 200%MAD, which is only ±
4.9% (1 σ).  Extrapolating from the lower elevation gauge (powerhouse) site to the intake site introduces
further uncertainty, estimated to be equal to the orographic enhancement of 7%/100 m difference in elevation
or 6.2% for 89 m difference.  Added in quadrature to the lower gauge uncertainty results in an uncertainty of
intake flows of ± 9.4% at 1 σ, or ± 7.9% for flows less than 200%MAD.  Therefore the MAD estimated at the
intake site is 5.44 m³/s ±9.4% (1σ).
Overall these estimates of MAD were lower than regional expectations, and it is hypothesized that a
significant amount of water is bypassing the gauge, and likely the intake, sites.  Civil infrastructure and
bedrock constrictions near the intake site are expected to force more of this flow to the surface, and the
estimated flows at the intake site, and the spot flow measurements near the intake site, reflect this hypothesis.   
The synthetic flow series at the powerhouse and intake site are considered to be good quality and reliable
within the uncertainty limits provided within this report.
Information Type report
Regional Watershed Howe Sound & Sunshine Coast
Sub-watershed if known Skookum Creek
Aquifer #
Project status complete
Contact Name
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