BRT4 in Bulgaria: the Kresna Gorge issue and the impressive Bulgarian ‘river intelligence’

BRT4 in Bulgaria: the Kresna Gorge issue and the impressive Bulgarian ‘river intelligence’

Before we came to Kresna gorge in Bulgaria, our final destination of Balkan Rivers Tour 4, we knew very little about the river conservation efforts in Bulgaria in general. But from the first day, when we were blown away by the memorable appearance of a team of local river defenders, we knew that we were in for a real treat. They have also highlighted the issue of Kresna gorge, a place with the highest biodiversity in Bulgaria, which could be lost for good.

These are just two from Dimiter Koumanov’s extensive ‘repertoire of complaints’ to the EU Commission, showing the interconnection between hydropower development, corruption, river destruction and local communities. (Source Koumanov Dimiter 2019)

Dark clouds rolling over the sunny Kresna Gorge

Biologist Andrey Kovatchev from Balkani Wildlife Society gave us an introduction about the geography and ecology of Kresna Gorge and the environmental threats it faces. The gorge is 18 km long, it lies in southwestern Bulgaria and it was carved by the Struma River. The Kresna Gorge is statistically the sunniest place in Bulgaria. The region has a dry Mediterranean climate, which makes the Struma River a narrow migration corridor for species and so its river bank is a lively place where their paths cross.

Kresna Gorge is a convergence zone of Mediteranean and Continental climate and it’s these conditions, combined with the remarkable ability of life being able to adapt to extremes and occupy different niches, which makes it the most ecologically diverse place in Bulgaria, and hence it’s protected by Natura 2000 Kovatchev (n/a).

Unfortunately, for a while now, there have been dark clouds rolling over sunny Kresna, in the form of development, which is subsidised by the EU. The Struma motorway is a part of Trans European Network for Transport, which aims to connect nine countries from Athens to central Europe. The locals know first-hand about marginalised communities lacking the infrastructure that would enhance economic development. However, in their case, the motorway going through the gorge would not only mean an economic loss, but also the complete devastation of the Kresna gorge. What pains them the most is knowing that there are alternatives to the motorway going through the gorge (e.g. a route for the motorway outside of the Kresna Gorge) but the government rejected them in 2017, due to the pressure from construction companies, according to Bankwatch (2019).

The problem is that the existing road would be turned into a motorway, which means there would be no local road left. The younger generation which has been working so hard on establishing tourism in the gorge over the past decade, in particular rafting, would find it extremely difficult to run their businesses without having a local road, and a lot of them would be forced to relocate to the city in search of work. The depopulation of rural Bulgaria is a pressing issue, in fact, it’s amongst the worst in Europe according to Margaras (2019), and young people should be by all means encouraged to stay. Another issue is the loss of fertile agricultural land, and even the area that wouldn’t be lost due to construction, would be impossible to cultivate, as it would become inaccessible. How on earth do authorities imagine farmers are supposed to access their land, by racing down a motorway in a tractor, or even a horse carriage? 

Another casualty would be the wildlife, which since the broadening of the road in 1997, has suffered enormously, ending up as road-kill, in particular the type that can’t fly over the gorge in order to cross it, which unfortunately, is the majority. The narrow migration corridor is confined to the bottom of the valley, which is exactly where the road will be. A study by Beshkov (2019), on road-kill shows a striking figure of species loss ( e.g. decline in numbers of endangered tortoises and snakes by 60%), and with the motorway being located in the gorge this would be like stabbing this magnificent mega-creature straight in the heart. 

Habitat change, predominantly habitat loss, is the main threat to Europe’s biodiversity. The state of European biodiversity is shameful, about 60% of species and 77% of habitats remain in poor condition, says a report on biodiversity by the European Environment Agency (2015).

Knowing how impoverished Europe is in terms of biodiversity, one would expect that the ecological gems of Europe would be protected, if not by national legislation than at least by European, such as Natura 2000. How does Europe dare to finance a motorway going through a place which constitutes one of the last remaining and precious European biodiversity hotspots?

The Hercules who will defeat the water monster Hydra

The story of Bulgarian river defence is truly inspirational. It is an impressive network of ‘river intelligence’ which comprises of mainly fishermen’s associations, and a few nature conservation organisations. Despite the fact that they appear to be small in numbers, they are big in action and spirit! Together they fight against small hydro dams that cause huge environmental damage to their rivers.

Dimiter Koumanov, a lifelong fisherman, a charismatic figure and a fearsome river defender, is at the forefront of defending Bulgarian rivers.

In one of his articles, Koumanov (2017) compares the impacts of hydro dams to Hydra, the indestructible water monster from Greek mythology, which has many heads and if you cut one off, two more would grow back in its place. The person who finally defeats Hydra is Hercules, and we believe that today’s Bulgarian Hercules is this team of river defenders.

The word small is deceiving with regards to the impacts of small hydro dams, as one would think small dams create small impacts. However, the situation is quite the opposite. ESHA (2009) claims in their study on the environmental impacts of small hydro dams that they cause just as big and irreversible damage to rivers as the big hydro dams. One of the issues with small hydro is the requirement of having a minimal residual flow, which remains in the river so that the river can still function as an ecosystem and sustain life. This minimal flow is often set too low to cater for the needs of downstream riverine ecology or is simply being completely ignored, claims Fischer, (2000). The insufficient flow below the dam creates a uniform flow, which alters habitat conditions which in turn results in the loss of diverse habitats, and that leads to a decrease in numbers and diversity of aquatic species, according to Schmutz, (2018)

Another adverse effect of hydro dams on river ecology is the prevention of fish migration upstream and downstream. There is an established consensus amongst aquatic biologists that the existing mitigating measures used on hydro dams are ineffective, says a report on impact assessment of dams Garandeau, (2014). According to Koumanov (2017), the situation is particularly bad in Bulgaria, because these fish passages in the form of fish ladders or fish steps, have in the majority of cases been found to malfunction. He says that the blocked fish passages are a common practice for two reasons. One is the decrease in the cost of hydro dam maintenance, because if they block the fish steps with a barrier, this prevents inlet grates from getting clogged by debris. The second reason is that by diverting all the water for hydropower production, then guess what, more electricity can be generated.

Fish steps at HPP Davidkovo 2, Davidkovska river, Natura 2000 site in Rhodope Mountains. Even experienced climbers would struggle to get over this wall, let alone fish, comments Dimiter Koumanov. (Source

As if the hydro dams don’t pose enough danger to Bulgarian rivers, there is yet another river killer on the rise, which has been present for decades, but it’s about to get even worse. Bulgaria and its neighbouring countries have a long history of base as well as precious mining according to Bird, (2010). 

There are severe impacts on human health and the environment associated with mining because of the prolonged residence time of heavy metals that accumulate in river sediments and floodplain soils, claims Macklin,( 2006) in a geomorphological study of rivers contaminated by heavy metal mining. The problem with these heavy metals is aggravated when a contaminated river is used for hydropower production. In a complaint to the EU Commission, Koumanov (2019) explains how the existing fifteen small hydro dams and another twenty proposed dams on the Iskar River will exacerbate the problem of heavy metal pollution in the river. When sediment accumulates in dams, they become pollution traps according to Todorova, (2016), and when the hydro power plant discharges the silt from the dam into the river, the high concentration of heavy metals kills all life downstream. Flushing of reservoir sediment has a negative impact on river ecology in itself, claims (Espa, 2019), let alone when it’s heavily polluted. When the Lakatnik HPP after just one year of operating, released thousands of cubic meters of toxic silt into the river, all aquatic organisms in the range of fifteen kilometers downstream died, reveals Koumanov (2019). When the silt is discharged from the first HPP in line, the next HPP downstream gets it, and then the next. Just imagine the massacre that happens each time when one of the HPPs releases the silt, then multiply that by fifteen.

In recent years, gold deposits have been discovered in Bulgaria, Kenarov1 (2011) and Serbia, Vasovic (2013), and since gold mining is the most polluting of all metal mining, we can expect even more heavy metals being discharged into rivers on a national as well as transboundary level. In Bulgaria, the locals fear gold mining would heavily pollute water and soil, explains Keranov2 (2011) and they stress that, “Our real treasure is not gold, but water.”

So how does the “Hercules river intelligence” work? One of the most effective tools, which is a collaboration between the Association “Balkanka Fishing Club”, WWF Bulgaria, and a fistful of other fly fishing clubs, is the development of an online platform which monitors HPPs in Bulgaria, (2019). This monitoring is done in a style of citizen science and they call it ‘permanent public control’. Due to the lack of interest from the authorities, they reckon more than 90 percent of all HPPs in Bulgaria don’t operate in line with legislation. The main goals of this online platform are to closely monitor adequate fish passages, fish kill caused by industrial pollution, residual minimal flow, treatment of silt, and controlled flushing of reservoirs. Information can be uploaded by anyone, in the form of pictures, stats, measurements and any additional information.

Bulgarian river defenders also have macroinvertebrates experts among them. Helena Huđek and Pencho Pandakov, members of the River Intellectuals network, provide studies of macroinvertebrates that serve as ecological indicators of river health. 

Once Balkanka gathers enough scientific evidence to file a complaint against a HPP, they write to the EU Commission, demanding to close it down. They are relentless, and they reap what they sow; they have stopped about 20 HPP either from operating or from being built.

Association ‘Balkanka Fishing Club’ has a unique story. Their transformation from being a conventional fishermen’s association to river defending activists is very uncommon and most admirable! Traditionally, fishermen prefer ‘quantity over quality’, which is a common practice across fishing communities throughout the world and has resulted in alteration or even destruction of river ecology and the extinction of endemic species.

In contrast, Balkanka has been doing some impressive pioneering work in the field of river conservation. Ivan Pandukov, the current president of Balkanka, says that their work includes the stocking of native Balkan trout,implementing conservation measures, working with academics to protect the endemic fish species, monitoring the HPPs, and filing complaints to the EU Commission.

The word hydro dam has amongst the general public in Bulgaria such bad connotations that over the past five years, not one student in Bulgaria has chosen to study engineering hydrology says Dimiter Koumanov. As he is telling us this, his face lights up with pride, just like a parent’s face would, after succeeding in raising a child with a good moral compass.

Despite the stark depopulation of rural areas in Bulgaria, and the initial concern about who is going to save Bulgarian rivers, when there is no one left to save them, we have been reassured that these rivers have fearsome river defenders on their side. If Hydra can grow back a head once it’s been chopped off, then the ability of Hercules’ network of river defenders with many hands and swords, is to chop off a head the moment it grows back, persistently, one by one, until Hydra is defeated. It’s the people of this calibre, with Hercules’ courage and shrewd strategy, that bring hope for Bulgarian rivers.

-Mojca Kralj

References – links to  main scientific articles used to write the blog

Bankwatch, Feb 25 2019. Kresna gorge / Struma motorway, Bulgaria.[online]. Available from: [Accessed 23 Oct 2019].

Beshkov Stoyan, 2019. Scientis’s statement on wildlife monitoring in Kresna Gorge, Bulgaria, by the Bulgarian Academy of Sciences National Museum of Natural History. [online].Available from: [Accessed 21 Oct 2019].

Bird, Graham & Brewer, Paul & Macklin, Mark & Nikolova, Mariyana & Kotsev, Tsvetan & Mollov, Mihail & Swain, Catherine. 2010. Contaminant-metal dispersal in mining-affected river catchments of the Danube and Maritsa drainage basins, Bulgaria. Water Air Soil Pollution.[online].pp. 206:105–127. Available from: [Accessed 22 Oct 2019]. (2019) Monitoring of existing HPP / SHPP in Bulgaria. Available from: [Accessed 20 Oct 2019]

Espa P, Batalla RJ, Brignoli ML, Crosa G, Gentili G, Quadroni S (2019) Tackling reservoir siltation by controlled sediment flushing: Impact on downstream fauna and related management issues.[online]. PLoS One 14(6): e0218822. [Accessed 19 Oct 2019].

European Environment Agency. 18 Feb 2015. Biodiversity Briefing. [online].Available from: [Accessed 19 Oct 2019].

Fischer S., Kummer H., 2000. Effects of residual flow and habitat fragmentation on distribution and movement of bullhead (Cottus gobio L.) in an alpine stream. In: M. Jungwirth, S. Muhar & S. Schmutz (eds), Assessing the Ecological Integrity of Running Waters. Netherlands: Kluwer Academic Publishers, pp. 305-317

Garandeau Régis, Stephen Edwards, Mark Maslin. 2014. Biophysical, socioeconomic and geopolitical impacts assessments of large dams:an overview. University College of London.[online].Available from: [Accessed 21 Oct 2019].
Kenarov Dimiter1 31st Oct 2011. Plans for Gold Mine Divide Bulgarians.The New York Times. [online].Available from: [Accessed 20 Oct 2019].

Kenarov Dimiter2 17 Nov 2011. Where Your Gold Comes From: the Story of an Exploited Town in Bulgaria.The Atlantic. [online].Available from: [Accessed 20 Oct 2019]

Koumanov Dimiter, Bankwatch 21 Dec 2017. Guest post: One beast with many heads – a hydropower hydra in the Balkans. [online]. Available from: [Accessed 22 Oct 2019]

Koumanov Dimiter 2019. Complaint to the Commission for the European Communities concerning failure to comply with community law. [online]. Available from: [Accessed 22 Oct 2019]

Kovatchev Andrey ( n/a). Save Kresna Gorge. International Union for Conservation of Nature. [online]. Available from: [Accessed 24 Oct 2019].

Macklin M.G., P.A. Brewer, K.A. Hudson-Edwards, G. Bird, T.J. Coulthard, I.A. Dennis, P.J. Lechler, J.R. Miller, J.N. Turner, (2006). A geomorphological approach to the management of rivers contaminated by metal mining. Geomorphology. [online] Volume 79, Issues 3–4, pp. 423-447. Available from:

Margaras V. 2019. Demographic trends in EU regions – European Commission. European Parliamentary Research Service. [online]. Available from: [Accessed 22 Oct 2019]

Schmutz S., Moog O. (2018) Dams: Ecological Impacts and Management. In: Schmutz S., Sendzimir J. (eds) Riverine Ecosystem Management. Aquatic Ecology Series, vol 8. Springer, Cham, pp.111-127.

SHERPA (The European Small Hydropower Association) 2009. Environmental barometer on small hydro power. [online]. Available from: [Accessed 22 Oct 2019]

Todorova, Yovana & Yotinov, Ivaylo & Lincheva, Stilyana & Topalova, Yana. (2016). Heavy Metals Impact on Sediment Microbial Communities in River-Dam Sequence of Small Hydropower Plant Cascade. Bulgarian Journal of Soil Science. Vol: 1. pp. 51-63. 

Vasovic Aleksandar, Eisenhammer Stephen  June 13, 2013. Serbia may be on cusp of mining revival after years of decline. Reutors. [online]. Available from: [Accessed 20 Oct 2019].