Offsetting for a hydropower project in Costa Rica

Applying the mitigation hierarchy to manage biodiversity risk

Source: world map and inset – Wikipedia.

View of Reventazon HPP © Olga Puntus/IFC (link)

The mitigation hierarchy – TBC graphic

Key biodiversity and impacts

The Reventazón River qualifies as Natural Habitat according to IFC PS6.

Potential impacts include: loss of 8 km of flowing river, a barrier effect on migratory fish species

entering 38 km of Reventazón River mainstream and tributaries downstream of Angostura HPP;

changed hydrology (sedimentation and water quality) in downstream Reventazón River, including

Tortuguero National Park.

Offsetting was required to:

Compensate for project impacts on the Sub-Corridor

Ensure no net loss of river Natural Habitat, and

Compensate for impacts on migratory fish species.

Overview

Most hydropower projects are likely to have residual impacts that require offsets to reach international

leading practice standards (e.g. IFC PS6).

The Reventazón HPP has pioneered the use of metrics to plan no net loss with the Parismina River

Offset , setting a best-practice standard for other HPPs in Costa Rica and globally.

This is perhaps the first direct offset of the impacts of a HPP on a river ecosystem, demonstrating

that no net loss HPPs are feasible under certain conditions.

However, it is important to highlight that no net loss is much more feasible for certain HPP designs and

environmental conditions, e.g.:

Run-of-the-river, rather than storage

Upstream in the watershed, rather than downstream

Downstream of existing HPP

Base-load energy production rather than peak-load

Small reservoir area

Toe of the dam powerhouse, rather than distant with a long dewatered length of river. The project

Name: Proyecto Hidroeléctrico Reventazón Hydropower Plant (HPP)

Developer: Instituto Costarricense de Elecricidad (ICE)

Location: Reventazón River, medium-sized, flowing into the Caribbean in

Costa Rica

Details: 305 MW - largest renewable energy project in Central America.

130 m dam, flooding of a 6.9 km2 area, creation of an 8 km long artificial

lake. Downstream of Angostura HPP

Investment: International Finance Corporation (IFC), Inter-American De-

velopment Bank (IADB) and others

The challenge

IFC Performance Standard 6 PS6 is for ‘Biodiversity Conservation and Sustainable Management

of Living Natural Resources’.

PS6 requires an assessment of Critical Habitat-qualifying features and assessment of Natural and

Modified Habitat.

PS6 requires net gain of Critical Habitat-qualifying features, and no net loss of Natural Habitat.

Net gain and no net loss are achieved using offsets and additional conservation actions.

Offsets are a measure of last resort to address residual impacts on biodiversity and ecosystem ser-

vices, after all other components of the mitigation hierarchy have been fully applied (see right).

Offsetting for no net loss of Natural Habitat

The Parismina River was identified as equivalent to the Reventazón River (like-for-like). This is an

averted loss offset - no HPP will be developed on the Parismina River in the future.

Method 1: ‘quality x length’ metric for structural connectivity.

No net loss is achieved when (in simple terms) water quality with offset actions in the section

of the Parismina River that would have been disconnected if a Parismina dam was constructed,

is better than the water quality in the section of river than will be disconnected by the

Reventazón project.

Method 2: a metric for functional connectivity of the river system, based on the abundance of

indicator species.

No net loss is achieved when with offset actions, species abundance in the relevant sections

of the Parismina River is greater than species abundance in the section of river than will be

disconnected by the Reventazón project.

Reventazon HPP © hydroworld.com (link)

Rio Parismina (Source: panoramio.com)

Contact Details:

enquiries@thebiodiversityconsultancy.com

The Biodiversity Consultancy,

3E King’s Parade, Cambridge, UK, CB2 1SJ

www.thebiodiversityconsulltancy.com Rio Reventazon © TBC Rio Parismina© Panoramio