eel protection devices and operations at the rimouski river hydroelectric powerplant: a win/win...

Eel protection devices and operationsat the Rimouski River Hydroelectric Powerplant:

a Win/Win approach that works

Guy Verreault and Jean Therrien

Ministère des Ressources naturelles, de la faune et des parcs du Québec

Genivar Consultants

Introduction

• Research / licensing process• Dam and hydropower plant rebuilt in 1996-1997• Eel migration surveys (upstream and

downstream) since 1994• Salmon and eel upstream and downstream

facilities• Downstream device tested: bypass with light in

1997, and with screen in 1998• Main task: eliminate turbine mortality without

significant loss of electricity production

Study area: Rimouski River

River drainage: 1637 km2

Mean annual water flow: 30.8 m3/s

Run-of-river 3.5 MW hydroelectric dam

Located 6.5 km from estuary

Maximum turbined flow: 26 m3/s

Water intake velocity: 0.7 m/s

STUDY AREA - DAM VICINITY

Downstream device

• In 1997, three components: a light barrier, a bypass, and a fine grid (1 cm) inclined screen (effectiveness evaluation)– Light device (90 W submersible mercury

bulbs, 40 Lux at 2 m with 30˚angle) in the water intake

– Bypass in the wall of spillway gate– Fine grid (1 cm) inclined screen behind

lighting barrier• In 1998, two components: a bypass and a

fine grid inclined screen.

BYPASS PLAN VIEW

The results

Ligth avoidance device

Sample Device Waterflow to device

m³/s

Waterflow

to turbines

m³/s

Efficiency

%

42 Halog 0.5

(7 eels)

4.7

(35 eels)

7.7

42 Halog 0.5

(7 eels)

9.0

(35 eels)

12.5

26 Halog

+ Hg

0.5

(0 eel)

8.8

(26 eels)

0

• Efficiency of the light system in 1997: 0 to 12.5%

• Unsufficient lighting on edges

• Backup screen diverted all migrants

Light avoidance behavior

• Current velocity was not too fast (Taft, 1998)

• Water flow in the bypass was correct (0.5 m3/s)• Problem lies in:

– Dark coloring of the water– Low intensity of lighting

• Behavioral barrier are not 100% effective with eel… (Hadderingh et al., 1992) and many other animals

• Field experiments may differ with laboratory observations

Experimental design: alternative diversion

Efficiency: 100%

• Physical barrier tested the following year

• Total efficiency when adequately installed

• Minor adjustments required for total diversion

• Great concern with leaf clogging

• Physical barrier is effective in any water condition

Clogging with leaves and debris was of great concern

Air compressors

Conclusion• High survival rates could be achieved

with simple device at small hydrodams

• Technical problems could be solved with imagination

• No significant loss in electricity production when protection devices are installed and well operated

• Moreover, strong involvement from dam operators is the main factor for a successful protection of downstream migrants