MS Dam Safety Program Dusty Myers, P.E. Chief, Dam Safety Division

A regulatory program to regulate the design, construction, operation, and maintenance of dams in order to protect downstream lives and property. Every state except Alabama has a dam safety program.

1)Determine hazard classifications of dams and maintain an inventory of dams in the state. 2)Review and approve all plans and specifications to construct new dams or modify existing dams. 3)Review inspections of dams and work with dam owners to bring their dams into compliance with the regulations.

4)Review and approve Emergency Action Plans (EAPs) for High hazard dams. 5)Periodically perform inspections of dams under construction and random inspections of existing dams. 6)Respond to dam failures and incidents.

Hazard Classifications and Dam Inventory

High Hazard–A class of dam in which failure may cause loss of life, serious damage to residential, industrial, or commercial buildings; or damage to, or disruption of, important public utilities or transportation facilities such as major highways or railroads. Significant Hazard—A class of dam in which failure poses no threat to life, but may cause significant damage to main roads, minor railroads, or cause interruption of use or service of public utilities.

Low Hazard—A class of dam in which failure would at the most result in damage to agricultural land, farm buildings (excluding residences), or minor roads.

Dams greater than 8 ft in height or 25 acre-ft of storage Dams smaller than this threshold can be regulated if they are determined to be high or significant hazard

There are approximately 1360 dams in the Pearl River Basin in MS with lakes greater than 5 acres. Currently, 54 of these dams are classified as high hazard and 10 are classified as significant hazard.

Emergency Action Plans

Required for high hazard dams Contains maps of the area that would be impacted and a listing of structures, roads, etc. that should be evacuated or closed Contains procedures for Emergency Detection, Evaluation, and Classification

Defines responsibilities of the dam owner and other parties Copies are sent to numerous parties including county emergency managers, local police and fire departments, NWS, E911 Call Center, etc.. Digital versions are also made available online to emergency responders via a web map

Emergency: Uncontrolled Release of Water Warning: Failure Could Happen at Any Time Watch: Potential for Failure Exists Advisory: Conditions that could lead to a failure situation have occurred

Dam Failures/Incidents

Big Bay Lake Dam in Lamar County, 2004 –57’ tall dam with a 900 acre lake –Dam Failure –104 homes/structures flooded or destroyed –No loss of Life

McCoy Lake Dam in Simpson County, 2014 –45’ tall dam with an approximately 20 acre lake –Dam built by owner without authorization and no engineering oversight –Owner noticed a slide in the downstream slope and attempted a controlled breach through a sandy hillside just upstream from the dam –The hillside eroded rapidly and led to an uncontrolled release of the lake coming within inches of flooding two homes downstream.

Albritton Lake Dam in Pearl River County, 2015 –33’ tall dam with an approximately 40 acre lake –Dam had numerous modifications made to it without authorization, the primary spillway failed around 2010 and the lake drained, mysteriously the lake refilled around –In January 2015, backwards erosion piping was occurring in the center of the dam over an old spillway pipe. –Lake was drained down about 20’ to relieve pressure on the dam.