Larji Dam Fishladder: an unlovely trinket, a deceptive ornament

Emmanuel Theophilus[1] (etheophilus@gmail.com)

The 126 MW Larji Hydropower project near Aut on the mainstem of the Beas is run by the Himachal Pradesh State Electricity Board (HPSEB)[2]. The dam is constructed a little downstream of the confluence of the two main tributaries upstream, the Sainj and the Tirthan, at the narrowest part of a spectacular gorge, towering with limestone cliffs. The impounded waters of this dam have, since its construction in 2006, drowned the access road to the entire upper Kullu valley including Manali and the hundreds of villages upstream, including access to the entire Lahul valley and the region of Ladakh over the high passes from this end. The HPSEB then constructed a 3 km long tunnel to enable passage of traffic, and many people have warned of the hazardous nature of the tunnel. The 220 odd gods that descend from different valleys, on the backs of people to the lower Kullu valley every year in autumn however, refuse to use this tunnel. This is what compelled the HPSEB to build and maintain this tunnel, and during autumn to winter, to keep the water-storage in the dam low to enable the passage of gods, who have been traveling this route for over three and a half centuries. It is remark-worthy though, that this dam constructed as recently as 2006, seems to be heavily silted-up already and the dark shadows of sediment-shoals are visible just below the waters of the reservoir[3].

Being among the most recently completed, the Larji dam is the only dam on the Beas that has a fish-ladder, so it was of particular interest to us. Seeing no guard at the security booth, we walk in to the HPSEB dam operating office, and ask to speak to an officer about the fish ladder. To our complete surprise, we are spoken to and even taken on a tour of the ladder by a foreman who has worked on the dam for many years.

Having seen an elaborate fish ladder on the Kuri Chhu river in Bhutan of doubtful effectiveness[4], we could not help but look at this one with hope and excitement. Located at around 1,000 meters altitude, this dam was clearly in the way of a host of migratory species of fish. If this ladder design was effective, then surely the ‘barrier’ problem to seasonal migration for breeding and dispersal would have been addressed. Here though, is what we saw and heard.

  1. For one, the flow through the fish-pass seems too small to create an ‘attraction flow’ for fish. But even more obviously, the downstream entrance of the fish ladder is a steep cascade over a couple of meters of broken masonry and rock, that would clearly be un-negotiable by any fish that does not jump that high[5].
Downstream entrance of Larji fish ladder: The 2 m high jump that fish require to enter the ladder can be seen here

Downstream entrance of Larji fish ladder: The 2 m high jump that fish require to enter the ladder can be seen here (all photos by the author)

2. The outlet from the dam reservoir into the fish ladder is blocked off by a metal grill-mesh that is narrow enough to trap flotsam like Bisleri water-bottles. The mesh seemed too fine to let Mahseer of breeding-age pass through, either upstream or downstream.

3. The fish ladder was in a serious state of disrepair. To our questions about whether the ladder worked or not, the foreman says honestly that it does not. We see the reasons for this when we walk down the ̴100 meter length of the fish-pass channel.

Fishladder can be seen in serious state of disrepair and blocked by broken concrete parts can be seen here

Fishladder can be seen in serious state of disrepair and blocked by broken concrete parts can be seen here

4. The Larji fish ladder seemed to be a hash of different designs of fish passes. There were four different design elements in this one fish-pass. It had a slotted-weir fishway design, a low gradient Denil fishway, a steep-pass Denil fishway and a plain concrete culvert on a grade design. Most of these slotted weirs were clogged with fallen rocks and debris from the slope above, and in places, the pools in them were over-flowing the weir in a vertical fall almost 2 meters high.

Steep-pass Denil fishway part of the fishladder can be seen here, water is flowing too rapidly here for any fish to be able to go upstream

Steep-pass Denil fishway part of the fishladder can be seen here, water is flowing too rapidly here for any fish to be able to go upstream. The water picks up momentum down an extremely steep slope with the baffles at 45 degrees to the flow, not offset to slow the water, but concentrating the force of the water in mid-stream flow. The slope seemed to be at almost 40 degrees angle, and the water was turbulent in the extreme in this section. A workable Denilway slope, even for the strongest of swimmers among fish, is not designed to exceed a slope of 20% at most. This was close to a 100% slope

5. The oblique baffles on a Denil fishway are supposed to be placed in a manner that provides staggered partial-obstructions that slow the water down at variable velocities to make it passable for fish. However, here we saw that the water picks up momentum down an extremely steep slope with the baffles at 45 degrees to the flow, not offset to slow the water, but concentrating the force of the water in mid-stream flow. The slope seemed to be at almost 40 degrees angle, and the water was turbulent in the extreme in this section. A workable Denilway slope, even for the strongest of swimmers among fish, is not designed to exceed a slope of 20% at most. This was close to a 100% slope[6].

This part of fish ladder is less steep Denil

This part of fish ladder is less steep Denil

The last part of the fishway was a plain concrete culvert on a grade channel, essentially a sloping channel, where even the concrete sides of the channel had toppled over into the river-bed, and the final drop was over a two meter fall into the downstream flow. I asked the foreman whether he knew whether fish managed to make it over this extreme gauntlet. He said that they did not, but that he often saw fish gather and concentrate at the bottom of the dam under the sluice gates, and make futile leaps in an attempt to get over the dam. Clearly, the Larji dam fish ladder is just an unlovely trinket, a deceptive ornament.

Watch a 41 seconds video showing how fast the water is moving through the Larji Dam fishladder at: http://youtu.be/grVaxXPdeyY, Video is by the author.

It seemed to me that the dam builders and operators, the HPSEB in this case, both at the design and the executive levels, were not serious about constructing a fish-pass that would work, and neither were they serious about this at the operation and maintenance aspects. Whether they were serious at all even at the conceptual level, to put in place a mitigation measure that actually helped migratory fish bye-pass the barrier of the dam, or was this part of the design merely to obtain environmental clearance, can only be conjectured about. That hydropower projects can devise deceitful strategies for obtaining environmental clearance is one thing, but what does this tell us about the Union Ministry of Environment and Forests, the Expert Appraisal Committee on River Valley Projects appointed by MoEF, the regional office of the MoEF, the state Fisheries Department and also the state pollution Control Board, who are all variously part of the approval processes for hydropower projects, when they get their environmental clearances based on such ‘mitigation measures’?

Larji Dam - about 100 m long fishladder channel can be seen on the right side

Larji Dam – about 100 m long fishladder channel can be seen on the right side

END NOTES:

[1] This article has been extracted from SANDRP’s publication: Headwater Extinctions: Hydropower projects in the Himalayan reaches of the Ganga and the Beas: A closer look at impacts on fish and river ecosystems, authored by Emmanuel Theophilus, for details, see: https://sandrp.wordpress.com/2014/12/16/new-publication-headwater-extinctions-impact-of-hydropower-projects-on-fish-and-river-ecosystems-in-upper-ganga-and-beas-basins/

[2] The 126 MW Larji project is also infamous for being the costliest hydro-power project per unit electricity generated so far in India. Finally built at a cost of R.s 10.27 billion, which was twice the estimated cost, the Vigilance department unearthed major financial misappropriation by HPSEB officials.

[3] The Larji Dam became infamous in June 2014 when 25 students were washed away downstream from the dam due to sudden and unannounced release of water from the dam, see: https://sandrp.wordpress.com/2014/06/12/nadiya-bairi-bhayi/

[4] https://sandrp.wordpress.com/2014/02/02/fish-ladder-at-kurichhu-hydropower-project-bhutan-some-thoughts/

[5] Other than loaches, those tiny finger sized fish that can even climb (squiggle technique) up high waterfalls, provided there is something like a water-slide at the margins of the fall. They however, are not migratory fish.

[6] CIFRI recommends that the speed of flow of water in a fish-pass should not exceed 2 meters per second. Please see ‘Status of fish migration and fish passes with special reference to India’. MK Das and MA Hassan. CIFRI 2008.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: