How sustainable hydropower can promote biodiversity

The UN demands urgent action on biodiversity. Sustainable hydropower can be part of the solution, writes Alain Kilajian of the International Hydropower Association (IHA).


Today, the United Nations is holding a summit on biodiversity under the theme ‘Urgent Action on Biodiversity for Sustainable Development’.

With keynote speeches from heads of state including China’s President Xi Jinping and Germany’s Chancellor Angela Merkel, the summit is expected to bring attention to the Earth’s declining biodiversity and demand immediate action to promote more sustainable practices.

The global picture is indeed grim. You don’t have to look far to see the loss of biodiversity around us. When is the last time you heard a song thrush sing? The World Wide Fund for Nature’s 2020 Living Planet Report summarises it pretty clearly: “Biodiversity is being destroyed at a rate unprecedented in history”. Forests are being cut down, oceans are being polluted and wetlands devastated. This type of destruction is leaving much of the global fauna without the essential habitat they need to survive, let alone thrive.

Human development is the main cause of this destruction. With new cities popping up left and right, the impact on biodiversity will only become more significant. Rapid urbanisation is not unique to China, with similar rates of development occurring in sub-Saharan African countries such as Nigeria, Ethiopia and the Democratic Republic of Congo. This type of development requires infrastructure, roads, industry, as well as buildings that need to be cooled down or heated up. This is a long way of saying: more cities need more energy.

Energy demand is expected to increase significantly over the coming decades, with much of the new capacity coming from renewable energy sources (fingers crossed) such as wind, solar and hydropower. Increasing clean energy sources is absolutely essential to reducing greenhouse gas emissions and meeting the targets of the Paris Agreement. But what impact does the renewable energy agenda have on biodiversity?

As advocated in today’s UN summit, developing more renewable energy is key to our fight against climate change but it needs happen in a way that does not harm biodiversity.

This is especially important for hydropower, which lies at the heart of the land-water-energy nexus. As the largest renewable energy, making up more than half of global renewable energy production, hydropower is part of the solution to protecting the planet’s biosphere – and all life on Earth – by decarbonising the global economy, slowing the pace of climate change and preventing pollutants being emitted from fossil fuels.

As with any river-based infrastructure, hydropower projects also have a relationship to local biodiversity: the freshwater bodies on which they are built are home to over 140,000 described species, including 55 per cent of all fish.

Rivers act as natural corridors for both aquatic and terrestrial species, helping maintain biodiversity value across landscapes. Rivers also provide essential services for humanity, including tourism, navigation, fishing and agriculture. Yet, the health of rivers continues to be challenged by growing pressures from human activities, including pollution, irrigation and agriculture and industry, as well as infrastructure such as dams and weirs. Studies show two-thirds of the longest rivers (over 1,000 km) are no longer free flowing and global freshwater vertebrate populations have suffered an 83 per cent decline between 1970 and 2014 with even higher rates amongst fish species. Only a small part of this is caused by hydroelectric dams, but the sector needs to stand up to its responsibilities.

The construction of a hydropower project will inevitably change the river on which it is built. Identifying the extent of these impacts, and managing them responsibly, is crucial to ensure the conservation of biodiversity.

The most common approach to managing biodiversity impacts from hydropower is by applying the mitigation hierarchy. The mitigation hierarchy – avoid, minimise, mitigate and compensate – is a sequential process. First, a project should always seek to avoid or prevent negative or adverse impacts. For hydropower, this can include changes in site selection or project design to avoid the flooding of critical biodiversity areas. When avoidance is not possible, projects should look to minimise adverse impacts. For example, a project can alter operational controls or implement environmental flows to minimise downstream impacts on river health. In cases where avoidance and minimisation are not practicable, projects should aim to mitigate and compensate the identified impacts. This can be done by restoring lost habitats and re-establishing biodiversity value to the affected area.

The internationally recognised Hydropower Sustainability Tools provide further guidance to industry on achieving good practice in hydropower development with regard to biodiversity conservation. By assessing themselves against the requirements of the Biodiversity and Invasive Species guidelines and assessment criteria, hydropower projects can demonstrate their commitment to biodiversity in line with international standards.

The tools’ performance criteria address ecosystem values, habitats and issues such as threatened species and fish passage in the catchment, reservoir and downstream areas, as well as potential impacts arising from pest and invasive species associated with the planned project. The intent is that there are healthy, functional and viable aquatic and terrestrial ecosystems in the project-affected area that are sustainable over the long-term, and that biodiversity impacts arising from project activities are managed responsibly.

An example of a project that was assessed using one of these tools, the Hydropower Sustainability Assessment Protocol (HSAP), is the Reventazón Hydroelectric Project in Costa Rica. The winner of the IHA Blue Planet Prize in 2019, Reventazón is one of the first Latin American hydroelectric projects to use a river offset approach. Their offset programme is based on environmental and social criteria and designed and implemented with local stakeholders. The main outcomes of the programme are the protection of a free-flowing river, improvement of water quality and riparian habitats, compensation for the loss of critical habitat and the creation of a biological corridor to safeguard critical jaguar habitats.

Impacts on terrestrial and aquatic connectivity, especially on migratory aquatic species, are among the most important priorities for hydropower developers and operators. One example of good practice in hydropower development with regard to migratory species is the Trevallyn hydropower project in Tasmania. In 2012, Trevallyn was among the first hydropower projects to be assessed using the HSAP. At the time of the assessment, the project identified a gap against good practice in the Biodiversity and Invasive Species assessment topic due to a lack of thorough monitoring. Since then, the project has not only expanded its monitoring programme but also installed a bypass especially designed for short-finned eels to help them migrate downstream.

In order that we help conserve biodiversity, industry, governments and NGOs need to work together to identify and address negative impacts of hydropower on biodiversity and come up with innovative solutions to avoid, minimise, mitigate and compensate these impacts as early as possible in the project cycle. Today’s UN Biodiversity Summit is only one step on a long journey towards a truly sustainable development.

As an association committed to advancing sustainable hydropower, IHA and its members have an important role to play in increasing understanding and promoting the adoption of international good practices on biodiversity management. To support project developers to identify such solutions, we will soon be publishing a how-to guide to assist practitioners and other stakeholders in identifying and managing biodiversity impacts.

To learn more about IHA’s work on hydropower sustainability or register your interest in receiving the how-to guide on biodiversity, please email us at The expected publication date is November 2020.

Privacy Policy