Blakely Mountain Dam Lake Ouachita

  

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 Mountain Dam - Lake OuachitaBlakely Dam is 231 feet high and 1100 feet wide.

Blakely Mountain Dam currently has a Corps of Engineers Dam Safety Action Classification

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
Releasing water thru Blakely Dam outlet pipe into Lake Hamilton side.  Blakely Dam Generator outlet pipes running.  Lake Ouachita High water flows into lake Hamilton through the water relese pipe.
Click to enlarge

Blakely dam tunnel construction around 1950   Lake ouachita Blakely Dam Under ConstructionConstruction of Blakely Dam looking west 1949Blakely Dam the construction era 1949 from lake side.
Blakely Dam Under Construction.
Photos Courtesy of US Army Corps of Engineers

Sectional Diagram of Blakely Mountain Dam.

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 water.

The hills that surround Lake Ouachita range up to 1,350'.

Lake Ouachita is located in Garland and Montgomery Counties, Arkansas,
13 miles west of Hot Springs, Arkansas.

Construction work has been completed 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 2007 which recommended reallocation of storage in Lake Ouachita to the Mid-Arkansas 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 Power Administration.
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 Puerto Rico. 
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.