This presentation created a lot of interest during the regional consultation on the Don Sahong Hydropower project hosted by the MRC in Pakse in December 2014

1. How new fish passage development can mitigate the impacts
of the Don Sahong Hydropower project on fish migration
A presentation to the MRC regional consultation site visit to Don Sahong
Hydropower Project by Dr Peter Hawkins on 11 December 2014

2. Potential social and ecological impacts of a dam
• Displace people from their homes and
livelihoods
• Trap particulate matter (sediment)
• Alter river flow pattern
• Drown wetlands and terrestrial ecosystems
• Spoil water quality
• Block fish migration path
12/12/2014 Slide 2

3. THE KHONE FALLS IS THE ORIGINAL DAM
ON THE MEKONG MAINSTREAM
Just like a man-made dam the Khone
Falls alter
• sediment transport,
• river flow, and
• are a barrier to fish migration
12/12/2014 Slide 3

4. Khone Falls Dam
Don Sahong
dam site
Great Fault Line
Landsat Image
12/12/2014 4

5. Khone Phapheng
significant barrier to upstream migrating fish

6. Tat Pho-Tat Liew Rapid - a barrier to upstream fish
migration in the Sahong Channel

7. Khone Larn rapids - a barrier to upstream fish
migration in the Xang Pheuak channel
May 2014
12/12/2014 Slide 7

8. Somphamit Falls – impassable barrier to
upstream fish migration in western channels
Image by Suthep Kritsanavarin

9. Scheme Location on Hou Sahong with overlay of
LEGEND
Waterfall/rapid
Head pond
Proposed Head Pond
12/12/2014 9

10. Artist impression of power house on lower
12/12/2014
Sahong Channel
Slide 10

11. Xang Pheuak and Sahong Channels from the air
12/12/2014
Power house
Hou Sahong
Slide 11

12. Damming Hou Sahong will not
…alter transport of particulate matter (sediment)
…alter river flow pattern downstream
…drown significant wetland or terrestrial ecosystems
…change water quality
…displace many people
Compared to almost all other Mekong Basin dams –
the impacts from Don Sahong will be insignificant
12/12/2014 Slide 12

13. So why are we all here today?
It is probably because of these statements **……….
Hou Sahong is the only channel that allows year round
fish passage across the falls
Hou Sahong is the only channel large enough to support
migration of big groups of large fish.
What scientific evidence supports these statements?
** “Roadmap Document” MRCS (Nov 2014)

14. Dr Ian Baird is the source of all these comments
Roberts & Baird (1995) concluded that Hou
Sahong was “the most important channel for all
migrating fish species at all times of the year”.
The same paper also said that Hou Xang Pheuak
is a “major pathway for fish migrating upstream
past waterfalls”
Hou Sadam is “important for all migrating
species during most of the year”
ROBERTS, T. & BAIRD, I. G. 1995. Traditional Fisheries And Fish Ecology On The Mekong River At Khone Waterfalls
In Southern Laos. Nat. Hist. Bull. Siam Soc., 43, 219-262.

15. What are the basis for Dr Baird’s claims?
The claims that Hou Sahong is the most
important migratory route and the only channel
that provides year round fish passage are based
on fishers stories

16. Quote from Baird (2011)
“local inhabitants and scientists who have
studied fish in the area widely believe that a
large proportion of the fish that migrate up the
Mekong River from Cambodia to Laos pass
through this [Hou Sahong] channel.
Locals declare that the Hou Sahong Channel is
by far the most significant migratory fish
passage year-round.”
BAIRD, I. G. 2011. The Don Sahong Dam: Potential Impacts on Regional Fish Migrations, Livelihoods and Human
Health. Critical Asian Studies, 43, 211 — 235.
12/12/2014 Slide 16

17. Now its time to separate fact from fiction
It seems that because many other learned
Professors have repeated the fishers stories
reported by Professor Baird
- they have become accepted scientific facts..
12/12/2014 Slide 17

18. What essential scientific evidence is missing from Dr
Baird reports?
Roberts and Baird 1995 report does not provide
any scientific observations of the relative
success of fish passage through any channel.
Baird’s data is from fishers catches, and fishers
fish for their living – not for science
DSPC fish monitoring program is collecting data
on relative success of fish passage for the first
time

19. What other scientific evidence is missing from Dr
Baird’s reports?
Fish need water – Baird provides no data on
flows but does say…
Sadam and Xang Pheuak are both important
upstream migration pathways for part of year
What were the flow patterns in the Sahong and
Xang Pheuak channels in the 1990s?

20. Daily flow in Sahong and Xang Pheuak derived from Pakse flow records
Baird Study Period Sahong and Xang Pheuak
Xang Pheuak
12/12/2014 Slide 20

21. Fast forward 20 years
THE HYDROPOWER ERA
MEKONG RIVER FLOW AFTER 2014
- A NEW ‘FLOW PARADIGM’
12/12/2014 Slide 21

22. The MRC “Definite Future Scenario 2015” is
already here
Base case
(2000)
Definite
Future
(2015)
Actual
(2014)
Active storage
u/s of DSHP (Mm3)
9,127 43,925 42,840
The “Definite Future Scenario 2015” is described in, MRC 2011. Assessment of Basin-wide
Development Scenarios: Main Report, Basin Development Plan Programme.
12/12/2014 Slide 22

23. In 2000, 9.1 km3 active storage upstream Don Sahong
12/12/2014 Slide 23

24. In 2014, there was 21 km3 of active storage upstream
of Don Sahong (excluding 2 Chinese dams)
12/12/2014 Slide 24

25. After 2010, Xiaowan added 10 km3 to active
storage upstream of Don Sahong
12/12/2014 Slide 25

26. After 2014, Nuozhadu Dam added another 12 km3
to of active storage upstream, of Don Sahong
12/12/2014 Slide 26

27. Cumulative impact of Hydropower development
on Mekong river Hydrology
• The hydropower era arrived definitively in June 2014
with the commissioning of the final turbine of the
Nuozhadu Dam
• Historical flow records will no longer be relevant for
predicting Mekong River dry season flows in the future

28. Flow at Khone Falls in the hydropower era
Xang Pheuak was reported as a seasonally
important fish passage in the 1990s.
In the hydropower era the increased dry season
flow will facilitate improvements to make the
Xang Pheuak channel a year round fish passage.
12/12/2014 Slide 28

29. Evidence the MRC ‘Definite Future Scenario 2015’ is here
- from increased median dry season flow at Pakse between 1990s and 2011-14
median flow
by month Q Pakse
[1990s]
Q Pakse
[2011+]
Q Pakse
% change
(m³/s) (m³/s)
Jan 2,506 3,089 23%
Feb 2,032 2,799 38%
Mar 1,720 2,663 55%
April 1,929 2,719 41%
May 2,600 3,757 44%

30. Median flow in Xang Pheuak and Sahong in the
dry season months in 1990s (Baird study period)
median
Q Sahong
Q Khone Larn
Q Khone Larn
flow by
[1990s]
[1990s]
[2011+]
month
(m³/s) (m³/s) (m³/s)
Jan 125 81 127
Feb 84 44 104
Mar 55 21 93
April 74 37 98
May 133 88 182

31. Dry season flow in Xang Pheuak at Khone Larn
since 2011 exceeds Sahong channel flows in 1990s
median flow by
month Q Sahong
[1990s]
Q Khone Larn
[2011+]
(m³/s) (m³/s)
Jan 125 127
Feb 84 104
Mar 55 93
April 74 98
May 133 182

32. Baird Study Period Sahong & Xang Pheuak
Xang Pheuak
12/12/2014 Slide 32

33. Hydropower Era
Xang Pheuak
Sahong
12/12/2014 Slide 33

34. Is improving fish passage feasible?
• Fish passage experts are regular visitors to DSPC
site
– MRCS Fish passage experts November 14 (2 days)
– World Fish Centre - November 14 (start 2yr project)
– US Army Corps of Engineers - September 14 (7 days)
– DSPC consultants (many months since 2009 )
• No fish passage expert on visiting the site has
ever said fish passage improvement is impossible
• All agree there are many options
– They do argue over the best way to do it
12/12/2014 Slide 34

35. Map of existing and planned fish passage work
12/12/2014 Slide 35

36. Measuring Fish Passage Performance
• Observing others catch fish is not adequate proof
of passage success
– Local people fish for food not for science
• DSPC has developed standard monitoring
methods
– Document at DSHPP.com
• Results published in peer review journals as
available
• DSPC aim to have a monitoring process which all
stakeholders can agree is suitable for assessing
fish passage effectiveness
12/12/2014 Slide 36