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Conservation Gateway » Conservation Practices » Water » Environmental Flows » Methods and Tools » ELOHA

Ecological Limits of Hydrologic Alteration (ELOHA)

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        ELOHA Home       Hydrologic Foundation          River Types​
Flow + Ecology​ Policy Implementation Case Studies Bibliography


Welcome to the ELOHA Toolbox!  ELOHA is a flexible framework for determining and implementing environmental flows at the regional scale using existing hydrologic and biological information.

In numerous case studies worldwide, water managers, policy makers, stakeholders, and scientists with diverse expertise are using ELOHA to accelerate the integration of environmental flows into regional water resource planning and management. 
ELOHA consists of the following steps, as illustrated in the framework flow chart
1. Build a hydrologic foundation of streamflow data,
2. Classify natural river types 
3. Determine flow-ecology relationships associated with each river type, and
4. Implement policy to achieve river condition goals.
For decades, environmental flow quantification has been conducted at the scale of individual river reaches, with a range of potential methodologies used to evaluate flow requirements. Holistic methodologies that account for all flow-dependent ecosystem needs are well-established (Tharme 2003), but can take years to complete for just one river reach. A more systematic approach applied at a watershed, region, or state-wide scale is required if freshwater ecosystem protection and recovery are to match the pace and extent of water resource development. Ultimately, this necessitates a scaling-up from site-by-site environmental flow provisions to the state, provincial, or national policy realm (Le Quesne et al. 2010). Only in this way will environmental flows become integral to all water management decisions from the onset, and not just as an inconvenient afterthought.
Regionalizing environmental flow management means making decisions that minimize ecological impacts of new water developments, direct water development to least-sensitive water bodies, and prioritize flow restoration efforts. These decisions hinge on a scientific understanding of how changes in the natural flow regime affect ecological conditions. The Ecological Limits of Hydrologic Alteration framework (ELOHA; Poff et al. 2010) helps water managers meet this challenge. 
Among the resources found on the ELOHA toolbox are:
·   Introductory Presentation in PowerPoint (13.5 MB) with notes explaining ELOHA step-by-step, illustrated with examples from around the world
·   List of multidisciplinary expertise needed to carry out ELOHA (or any comprehensive environmental flow assessment).
·   Case studies illustrating the various steps of ELOHA
·   Sample proposals from ELOHA projects that have been funded
·   ELOHA Bibliography of useful reports and articles