ALEXANDRIA,
VIRGINA. U.S. Army Corps of Engineers (Corps) multi-purpose reservoir
projects manage the risks of flooding, ensure reliable supplies of water for
public health and economic production, generate clean and affordable
electricity, provide safe and enriching opportunities for water-based
recreation to the public, and maintain adequate levels of streamflow to support
navigation and commerce on the inland waterways, aquatic and wildlife habitat,
and water quality. Many of the Corps dam
and reservoir projects have passed the end of their original 50-year planning
lives and are entering a life-cycle phase of long-term maintenance and
modification. In 2008, the Corps began
the National Portfolio program with a survey and assessment of the reservoir
project portfolio in support of its overall strategic goal of managing the
life-cycle of water resources infrastructure systems in order to consistently
deliver sustainable services. This
report presents major findings of the survey, discusses considerations and case
studies related to project modifications, as well as ongoing work and next
steps to better understand the status and challenges in continuing to operate
and maintain these complex and dynamic projects to best serve the evolving needs
of today and future generations.
The
survey collected information on water management, water supply and reservoir
sedimentation at 465 reservoir projects across the United States that together
impound about half of all constructed reservoir storage space in the
country. The water management portion of
the survey developed over 37 million daily measurements of inflows, storage and
releases; the equivalent of an average forty year period of record for the
surveyed projects. The survey effort was
leveraged to add water supply data to the Corps operations management database,
enabling tracking and reporting for the hundreds of water supply storage
agreements that the Corps maintains with state and local interests across the
country. The survey of reservoir
sedimentation assisted with cooperative development of the national Reservoir
Sedimentation (RESSED) database.
In
subsequent years, assessments and products were developed focusing on these
areas, as well as considerations related to environmental concerns and future
uncertainty. A 2010 assessment of water
supply needs led to a priority list for water supply storage reallocation
studies at 52 projects across the country.
Through the normal budget and appropriations process, the Corps has
since been able to fund study work at 26 of the 52 priority projects, as well
as 10 other projects that were identified as needs evolved. The Corps Committee on Water Quality assessed
ongoing efforts to improve water quality and ecological functions through
relatively simple structural and operational modifications, as well as evolving
water quality and ecological concerns that may challenge the Corps in meeting
the authorized purposes of dam and reservoir projects. Since 2010, cooperative work with the Nature
Conservancy’s Sustainable Rivers Program has been funded through the National
Portfolio program. A 2013 pilot study
assessed the use of down-scaled global climate model data in forecasting
conditions related to future streamflow and reservoir operations.
Next steps for the National Portfolio program are recommended to
continue in these areas of concern, and include developing methods, tools and
training to better inform the complex tradeoff considerations that are involved
in assessing modifications to multi-purpose reservoir projects; continuing to
periodically collect and assess water management data; developing policy and
technical guidance related to project modifications to enhance water quality
and ecosystems; and collaborating with ongoing efforts to better understand
risks and obstacles related to sedimentation and sediment management and the
potential impacts of climate change at dam and reservoir projects.
Download
2016-RES-01