ASDSO Dam Safety Toolbox

Inactive/Dead Pool/Storage

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The inactive/dead pool, also known as the dead storage refers to the portion of the reservoir that lies below the minimum operational water level. It represents the volume of water that cannot be effectively utilized for water supply, power generation, or other beneficial uses. It ensures a sustainable water supply, protects the environment by maintaining minimum flows downstream, and helps to maintain a stable reservoir level during dry periods and drought conditions. It supports ecological functions, such as maintaining instream flows, preserving aquatic habitats, and protecting downstream ecosystems.

When determining the inactive/dead pool storage of a dam, the anticipated water demand, reservoir capacity, inflow patterns, evaporation rates, and downstream water requirements are considered. There must be a balance between water supply needs and environmental considerations. It ensures that an adequate volume of water remains in the reservoir to sustain the downstream environment and ecological functions during periods of low inflow or drought.

The inactive/dead pool has significant environmental implications, particularly in terms of downstream ecosystems and aquatic habitats. By maintaining a minimum reservoir level, it ensures the availability of instream flows, which are crucial for supporting fish populations, maintaining water quality, and preserving overall ecological health. The dead pool helps to prevent the complete dewatering of downstream river reaches, protecting sensitive habitats and maintaining the connectivity of the aquatic ecosystem.

Reservoir operations and water management strategies consider the inactive/dead pool when maintaining a balance between water supply needs and environmental sustainability. Reservoir operators monitor water levels, inflows, and water demand to ensure that the inactive/dead pool is not unnecessarily utilized and that the minimum operational level is maintained. Operational rules and release strategies are implemented to optimize water allocation, considering the downstream flow requirements, ecological considerations, and the need for maintaining water supply reliability.

Effective management of the inactive/dead pool requires adaptive approaches and stakeholder engagement. Ongoing monitoring, data collection, and scientific research help assess the ecological impacts and determine the adequacy of the pool volume for maintaining downstream flows. Stakeholder engagement involving local communities, water users, environmental groups, and regulatory agencies is essential for understanding the trade-offs between water supply and environmental sustainability. Adaptive management practices ensure that reservoir operations and dead pool/storage considerations are regularly evaluated and adjusted to accommodate changing hydrological patterns, climate variability, and evolving water management needs.

Best Practices Resources

Hydraulic Design of Spillways (EM 1110-2-1603), USACE


Revision ID: 7783
Revision Date: 01/03/2024