Blakely Mountain Dam Construction began in 1948 and ended n 1953 when the gates were closed, creating Lake Ouachita.
Longitude: -93° 11' 40"
Latitude: 34° 34' 20"
Blakely Dam is 231 feet high and 1100 feet wide.
Blakely Mountain Dam currently has a
Corps of Engineers Dam Safety Action Classification (DSAC) III rating.
DSAC Class III (High Priority) – Dams that have issues where the dam is
significantly inadequate, or the combination of life, economic or
environmental consequences with probability of failure is moderate to high.
The flood pool is 578' feet above sea level. If the level reaches 592'
the water would flow through an emergency 200 foot wide spillway one mile west of the dam and then into Lake Hamilton via Owl Creek.
The deepest area is a little over 200 feet.
This has never happened since the gates where closed in 1953, however in December 1982 - January 1983, the lake did reach 591.2 feet,
just .8 of a foot short of going through the spillway.
Releasing water from Lake Ouachita
Click to enlarge
Blakely Dam Under Construction.
Photos Courtesy of US Army Corps of Engineers
The lake averages about 50 feet in depth with the deepest area approx. 200 feet.
The public area of Lake Ouachita covers 82,000 acres.
At 578 feet, 40,100 acres
is covered by the lake creating a shoreline of 690 miles.
At 592 ft Lake Ouachita has a 975 mile shoreline and and 48,300 acres of
The hills that surround Lake Ouachita range up to 1,350'.
Lake Ouachita is located in Garland and Montgomery Counties,
13 miles west of
Construction work has started on a contract issued by
The Corps of Engineers on a
new monitoring system to keep an eye on seepage at Blakeley Mountain Dam.
The monitoring system is part of the analysis and response to the 2005
inspection within the overall dam safety program.
Studies were completed in Apr 07 which recommended reallocation of
storage in Lake Ouachita to the
Water Alliance (MAWA) for M&I water supply. The reallocation study was
performed at the request of MAWA to purchase enough storage to yield 20
million gallons per day in Lake Ouachita. The proposed reallocation
would raise the top of the conservation pool by 0.82 foot.
In May 06, a risk
assessment screening was performed for Blakely Mountain Dam as part of the
Corps-wide dam safety initiative. Blakely Mountain Dam was classified as
DSAC II largely due to recently discovered anomalies in the under-drain
system which occurred during construction of the dam. Water reallocation by
raising pool elevations is inconsistent with DSAC II dam guidance until
corrective measures can be taken. Further studies directed at water
reallocation from the conservation (hydropower) pool which would not involve
raising pool elevations are being conducted. Studies involve preparing a new
Environmental Assessment directed at conservation pool reallocation and
coordination with the Hydropower Analysis Center (HAC) and the Southwestern
The study is scheduled to be completed in FY 10.
The Dam Safety Action Classification System (DSAC) is intended to provide consistent and systematic
guidelines for appropriate actions to address the dam safety issues and deficiencies of USACE dams. USACE dams are placed into a DSAC class
based on their individual dam safety risk considered as a combination of probability of failure and potential life safety, economic, environmental,
or other consequences. The DSAC table presents different levels and urgencies of actions that are commensurate with the different classes of the
safety status of USACE dams. These actions range from immediate recognition of an urgent and compelling situation requiring extraordinary
and immediate action for unsafe dams through normal operations and dam safety activities for safe dams.
DSAC Class I (Very High Urgency)
Dams where progression toward failure is confirmed to be taking place under
normal operations and the dam is almost certain to fail under normal operations within a time frame from immediately to within a few years
without intervention; or, the combination of life or economic consequences with probability of failure is extremely high.
DSAC Class II (High Urgency)
Dams where failure could begin during normal operations or be initiated as the consequence of an event. The likelihood of failure from one of
these occurrences, prior to remediation, is too high to assure public safety; or, the combination of life or economic consequences with
probability of failure is very high.
DSAC Class III (Moderate Urgency)
Dams that have issues where the dam is significantly inadequate or the
combination of life, economic, or environmental consequences with probability of failure is moderate to high.
DSAC Class IV (Low Urgency)
Dams are inadequate with low risk such that the combination of life,
economic, or environmental consequences with a probability of failure is low
and the dam may not meet all essential USACE engineering guidelines.
DSAC Class V (Normal)
Dams considered adequately safe, meeting all essential agency guidelines and
the residual risk is considered tolerable.
U.S. Army Corps of Engineers (USACE) owns 694 dams, Nationwide and in
USACE dams deliver enormous benefits to the nation, including
flood risk management, navigation, hydropower, water supply, fish and
wildlife conservation, and recreation.
USACE dams avoid $236 billion in
direct damages and preserve $25 billion a year in economic benefits.
Approximately 95 percent of the dams managed by USACE are more than 30 years
old, and 52 percent have reached or exceeded the 50-year service lives for
which they were designed.
Approximately 15 million people are at risk from USACE dams.