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 How can community members see the USGS gages?

There are three gages accessible to community members.

During a high water event, Baltimore District activates an emergency website at its homepage: www.nab.usace.army.mil Links to the water resources page are available to the community to see the conditions of Baltimore District reservoirs. The direct link to the water resources homepage is www.nab-wc.usace.army.mil/index.html

To see gages located on the streams, residents can go to United Stages Geological Survey website.

To see stream gages with river level projections, visit the National Weather Service website

 How does a dam work?
Dams are structures that control the amount and flow of water in a river, stream or creek from one side of the structure to the other, using various types of outlet gates or structures. During a high water event, the gates can be closed to store water that would otherwise have naturally flowed downstream and caused flooding, thereby providing flood protection and flood damage reduction for downstream communities. The water that is held behind the dam backs up into an area, forming a reservoir. When downstream conditions are such that hydraulic engineers and dam operators can begin releasing the water downstream, gates are slowly opened to return the reservoir level to its normal level.
 How does a resident obtain information on whether or not a certain dam is owned by the Corps?
A resident can go to go to the Corps website and click on “Dams & Recreation” on the “Missions” drop-down tab, and then proceed to click on “Water Resources Page” link. There are also state sections within “Dam and Recreation,” where the resident may select specific dam information for projects within New York, Maryland, West Virginia, and Pennsylvania.
 How does this data help you determine how much water to release?
By collecting information about river states and flows and their increases and decreases from several hundred data collection platforms over time, the hydrologists can effectively regulate the Corps dams to minimize impacts downstream. The system assists engineers in deciding when to close or throttle back water flow through the network of 15 dams to provide maximum flood damage reduction benefits to downstream areas. Through the use of computer charts and close coordination with the National Weather Service’s River Forecast Center, significant water movement can be identified, examined and predicted.
 How is the district's geographic area of responsibility determined?
U.S. Army Corps of Engineers flood damage reduction area of responsibility is determined by watersheds. For Baltimore District, our area of responsibility falls within the Susquehanna River and Potomac River watersheds.
 If your project is designed to protect against a 100-year flood, what does that mean?
A project built to protect against a 100-year flood event means that it protects against a flood that has a one in one-hundred chance of happening in any given year.
 What does the Corps do with its dams during a high water event?
Baltimore District hydraulic engineers monitor water levels in the region’s major rivers and regulate Corps-managed dams and reservoirs to minimize downstream impacts. Engineers in the Corps’ Reservoir Control Center receive electronic data from satellite imagery and river gages, as well as real-time reports from its field personnel on the ground, to help make decisions on when to open and close the gates at the dams. During this time, teams of engineers at the dams are inspecting and monitoring the performance of the structure and taking the necessary action to ensure the safety of the surrounding communities.
 What information does the Corps use to determine when to release water and how much to release?

Baltimore District hydraulic engineers monitor water levels in the major rivers throughout the region and control the flow of water at Corps-managed dams and reservoirs to minimize downstream impacts. Engineers in the Corps’ Reservoir Control Center receive reports from its field personnel on the water content across the Susquehanna and Potomac River Basins in New York, Pennsylvania, West Virginia and Maryland.

If the high-water event is attributed to snow melt, engineers in the Corps’ Reservoir Control Center monitor the depth of snow cover throughout the region and control the flow of water at Corps-managed dams and reservoirs to minimize downstream impacts.

 What is a spillway?
The spillway is the last line of defense a dam has before water goes overtop the walls of the dam. It functions just like a drain hole near the top of the edge of a bathtub or sink by directing the flow of excess water. During a high water event, when a dam is storing water for downstream flood damage reduction, the level of the water in the reservoir will rise as water from the upstream drainage area continues to flow into the lake. The spillway provides a gradual means for water to be released from the reservoir to prevent the dam structure itself from being completely overtopped. In most cases, the spillway is located to the sides of the dam. At East Sidney Lake, the spillway is a notch located at the top of the structure.
 What is the newest dam?
The newest dam built by the U.S. Army Corps of Engineers, Baltimore District is Jennings Randolph Dam in Pennsylvania, which became operationally complete in 1981.
 When do you decide to close the gates at a dam during a high water event?
The Corps begins to close the gates based on a combination of data from United States Geological Survey river gages, information on the ground from the dam operators and satellite imagery that indicates a need to hold water upstream to reduce flooding downstream. The process of slowly closing the gates and reducing the volume of water being released downstream is referred to as “throttling back” water flow. The satellite imagery used is called the Geostationary Operational Environmental Satellite, known as GOES East or GOES-12. It provides advanced weather imaging of water levels at our dams, river levels, rainfall and air temperature, and it records this data every 15 to 30 minutes.


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 Are rocks stronger than earth?
Yes, but rocks are only used in areas where high water velocity and activity are likely to pose a threat or danger to a community. Generally, earthen levees provide enough protection to prevent their surrounding communities from flooding.
 Do levees have steel walls underneath them?
No, levees are not constructed using steel. Typical levees are made with earthen fill and material.
 How does a leveel work?
Levees are earthen structures with impenetrable clay-like cores that are built between the land and a body of water. They are specially designed to allow rivers to rise, while preventing water from flowing onto the land side of the levee. During a high water event, they are designed to collect storm water at their base on the land side and pump it to the water side.
 If your project is designed to protect against the 100-year flood, what does that mean?
A project built to protect against a 100-year flood event means that it protects against a flood that has a one in one-hundred chance of happening in any given year.
 What can you expect to see on a levee during a high water event?
In any earthen structure, you can expect to see some clear water, or seepage, coming out from under the structure. This is called controlled seepage and it is factored into the design of the levee as a normal function.
 What is a sand boil?
Sand boils can be a mechanism contributing to liquefaction and levee failure during floods. This effect is caused by a difference in pressure on two sides of a levee or dike, most likely during a flood. This process can result in internal erosion, whereby the removal of soil particles results in a pipe through the embankment. The creation of the pipe quickly picks up pace and eventually results in failure of the embankment. A sand boil is difficult to stop. The most effective method is by creating a body of water above the boil to create enough pressure to slow the flow of water. A slower flow will not be able to move soil particles. The body of water is often created with sandbags forming a ring around the boil.
 What will the Corps do at a levee during a high water event?
On a levee built by the Corps, we deploy a team of engineers and specialists to monitor the project and provide the local levee owner with technical advice and support. When requested, we perform “levee patrols,” in which Corps engineers walk the length of the project with the levee owner to monitor its performance. If the project requires immediate repairs during the event, the Corps is able to provide technical assistance to the customer so they can make necessary repairs and take necessary actions to protect the safety of the community.
 Who inspects the levees and how often?
Engineers from the Baltimore District evaluate the levees each year. The team is led by a licensed professional engineer with experience in the design, construction and operation of a levee. The final inspection report undergoes an independent technical review, in which additional professional engineers review and approve the report. Levee owners are encouraged to participate in the inspection process.


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 How can a private citizen request sandbags?
The Corps does not provide individuals with sandbags. A private citizen will be referred to their local authorities (town, county, or state emergency managers) for assistance.
 How does a local authority obtain sandbags?

All requests for sandbags must come through the state. Local authorities must go up their chain of command - town, county, state. Under PL 84-99, the Corps can issue sandbags to local authorities, but only after the state has requested them. If local residents request sandbags, they should be directed to contact their local Emergency Management Agency.

 What is a Planning and Response Team, and what are its responsibilities?
The Corps coordinates federal public works and engineering related support during natural and manmade emergencies. The Corps uses Planning and Response Teams to respond to these emergencies. Each team is organized by mission area and is comprised of Corps employees who volunteer and undergo special response training. Primary mission teams include: Commodities, National Ice, National Water, Temporary Emergency Power, Debris Removal, Temporary Roofing, Temporary Housing, Infrastructure Assessment and Urban Search and Rescue.
 What is the protocol for a citizen reporting on debris in the water?
Debris in navigation channels should be reported to the local emergency management authority for assistance. If the debris is located in the federal channels for the Baltimore Harbor and Potomac and Anacostia Rivers in the vicinity of Washington D.C. (go to http://1.usa.gov/10i6I8z for channel maps), it should be reported to the Corps of Engineers Navigation Branch at 410-962-6113.
 Where does the public obtain information related to debris forecasts?
Public inquires regarding debris forecasts should be made to the State Emergency Management Agency Office (Public Affairs Office).