Herbert Hoover Dike
Lake Okeechobee covers approximately 730 square miles, with an average depth of nine feet. The dike ranges from 32-46 feet above sea level along its 140 mile length. There is significant probability of failure due to the construction methods used to create this dike beginning in 1932 and completed in 1971. The current structural condition of the dike calls into question the adequacy of the dike to withstand extreme wind and rainfall conditions.
Geologically, the lake is surrounded by sediment containing both shells and sandy material. Soil erosion, known as "piping" can create large cavities in the dike. Land elevations surrounding the lake in the southern portion are near sea level, with higher elevations on the northeast corner, in Martin County. Greatest threat of breach is in the southeast portion of the dike (Palm Beach County). Martin County has concerns about the affect a breach of the Herbert Hoover Dike may have on the S80 Water Control Structure (St. Lucie Locks) in Martin County.
- Water flow would follow natural geographical contours
- No notice event (non hurricane) resources would be more available
- A breach of the dike does not automatically predicate a failure of the S80 structure
- Population in area immediately along the lake is approximately 500 people.
- Speculated population in S80 flooding area 14,000 - the area of the S80 structure has not been modeled for flooding inundation. This area coincides with models for surge in a Category 5 hurricane.
- Without flooding data it is speculation Maps depicting anticipated flooding from S80 are estimated based on category 5 storm surge models, Based on historical data: October 1979 FP&L power plant dike breach
- Potable water contamination
- Access/egress due to flood waters
The Martin County Herbert Hoover Dike Plan addresses:
- Notifications in the event of a breach
- Evacuations – hurricane and no-notice event
- Public reunification/information centers activated at public libraries
- Sheltering for hurricane and no-notice events
No notice events do not have to be ARC 4496 compliant so can be in locations other than schools
Hurricane Evacuation Notices:
Changes have been made to include all areas with potential threat due to breach of the dike and/or S80 water control structure.
- Activation of the PIO and public information releases
- Pre-staging of assets and staging areas
- No critical facilities identified within the anticipated flood areas
Army Corp of Engineers Condition Classifications:
- Watch Condition: A potential failure situation is developing. A dike failure may eventually occur, but preplanned actions may moderate or alleviate failure.
- Non-Failure Emergency Condition: There is no danger of dike failure, but flow conditions are such that flooding is expected to occur downstream of the spillways.
- Evacuation Condition: Failure is imminent or Has Occurred. A failure either has occurred, is occurring, or is obviously about to occur.
Martin County Emergency Management continues to work with the State Division of Emergency Management, the USACE and SFWMD on updated information needed for the HHD annex.
Once updated flood inundation data is completed and made available Emergency Management will update the final draft of the plan to address:
- Population impacts;
- Population notifications and public information;
- Necessary evacuation orders;
- Mapping depicting flooding areas;
- Critical facilities and infrastructure impact.
For more Dike information:
Contact Phone Numbers: