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RE: dam-l 40 MW, low head, run-of-river dam

Shelley,
 
A quick note from the next province over.
 
It really depends on the project, and in particular its operations.  Here
are a few details to look into.  
 
1)  You said it was run of the river (ROR).  I'm wary of that term as there
can still be impacts within that type of dam/operation.  Run of the river to
most implies that there is no seasonal storage (e.g.. storing meltwater into
the winter), but there might still be fluctuations in both the reservoir and
downstream on a shorter time scale.  Flow fluctuations on the daily scale
downstream of dams refered to as ROR can have a significant environmental
impact.
 
2) Which river are they proposing to build this dam on.  ROR dams still
block fish movement.  However if there is a falls on the river d/s and
nearby this concern would be lessened.
 
3) ROR dams can still affect d/s water temperatures, though this might be
accomodated into their design.
 
4) Low head does not mean low reservoir storage volume.  The Keenleyside Dam
on the Columbia River is low head (17m) but impounds a lot of water.
(Incidentally a project has recieved approval to install 150 MW capacity
powerhouse in conjunction with that dam.  You might find some information on
the internet by looking under the BC Environmental Assessment Office.   The
project should still be listed on their project list and at least some of
the review information provided.)  More details are needed on this to
evaluate potential impacts.  I'd guess that they would not proposed a
significant impoundment as it would then be advantageous to operate in a
non-ROR manner.
 
5) Entrainment of fish still occurs at ROR dams, and is a contravention of
the Federal Fisheries Act (See section 35(2) I believe).
 
6) Elevated total gas pressure can still occur at ROR plants.  They might
even be more prone to it b/c there is probably a greater likelihood of
spill, given that flows fluctuate and turbine capacity would be less than
annual maximum flows.  If turbine capacity is at or near annual maximum
flows, and if there is significant seasona variation in flows I would be
concerned about whether peaking or load following would be part of the
proposed operations.  Again TGP can be considered at the design state and
impacts at least minimized.
 
7) What would the project discharge into.  If its a river then flow
fluctuations are more of a concern that if it were a lake or a d/s
reservoir.
 
8) Lastly regarding information I don't think you'll find much at the public
libarry level.  You might try going to one of the university libraries and
possibly accessing the primary literature.  Try doing some searching in the
Aquatic Science and Fisheries Abstracts (ASFA).  They're on CD and should be
available through university libraries.  
 
Also a lot of reviews of small hydro facilities don't seem to get beyond the
grey literature and government review processes.  You might look into
similar sized projects in Alberta and find what issues came up when they
were reviewed.  There are a few proposals of similar MW capacity in BC, but
all are diversions not ROR.  They would be much help as examples I don't
think.  The main issue with most of them is the downstream flow regime after
water is diverted out for power generation.
 
Hope these comments are useful.
 
Steve McAdam
 
 
 
 
 

-----Original Message-----
From: Shelley Skrepnek [mailto:shelleys@telusplanet.net]
Sent: Wednesday, July 14, 1999 8:49 PM
To: dianne@sandelman.ocunix.on.ca
Subject: dam-l 40 MW, low head, run-of-river dam


Hello Dianne,
 
Glacier Power Ltd. of Calgary is proposing the construction of a 40 MW, low
head, run-of-river dam 3 km upstream of the Dunvegan bridge near Fairview,
Alberta.  I can't find any information on low head, run-of-river dams on the
Internet or at the Public Library.  The council for the Municipal District
of Fairview is dancing with joy over this.  As an environmental activist,
should I be concerned about this dam?  Do you have any information on the
environmental effects caused by dams of this type?  
 
Thank you.
 
Shelley Skrepnek