Understanding Local Flood Stage Maps
- What is a Flood Stage Forecast Map?
- Who uses Flood Stage Forecast Maps?
- What are the benefits of Flood Stage Forecast Maps?
- How are Flood Stage Forecast Maps Used?
- Susquehanna River Basin Flood Facts
- Training Available
- Available Flood Stage Forecast Maps
During the late 1970s through the early 1980s, the Susquehanna River Basin Commission (SRBC) prepared flood stage forecast maps - using a technique the Commission developed - for all or portions of 90 basin communities. SRBC is now preparing maps for additional communities, and updating the existing flood stage forecast maps as necessary.
What is a Flood Stage Forecast Map?
Flood stage forecast maps reflect a range of stream stages that are tied to forecast points such as at Harrisburg and Williamsport. The maps provide details of flood plain areas and flood profiles with water level contours to show and wxplain what areas in a community will be inundated as flood waters reach certain flood stages. It is important that community officials and residents understand what will happen to their community when the basin's waterways are above flood stage, especially since our basin is so flood prone.
SRBC developed the maps using the flood profiles generated for the federal flood insurance program and relate to stream gages operated and maintained by the U.S. Geological Survey. The National Weather Service uses the data from the stream gages to produce a forecast stage at each of these forecast points. Each map identifies the location of the stream gage used in preparing the map.
The maps convert forecasted flood stages, issued by the National Weather Service, into areas of inundation for communities within the map study area. The maps show what the forecast stage levels will look like on the ground.
back to topWho uses Flood Stage Forecast Maps?
Emergency personnel; to identify areas that will be inundated first; municipal officials to develop flood evacuation plans; and individuals to easily determine how the forecasted flood will affect them.
back to topWhat are the benefits of Flood Stage Forecast Maps?
The proper use of a flood stage forecast map can help:
- Save Lives
- Reduce Property Damage
- Facilitate in Developing Evacuation Plans
- Provide Local Interpretation of National Weather Service Flood Warnings
How are Flood Stage Forecast Maps Used?
Flood stage delineations are placed usually at 5-foot intervals, indicated by contour lines on the map. The intervals are determined based on the topography of the flood plain. When a reliable source, such as the National Weather Service, predicts the expected flood stage for a specific event, the map can be used to determine what areas will be affected.
The maps depict the streets in the flood plain for easy interpretation when determining evacuation plans. The intervals on the map are generally adequate for interpretation.
Each map shows the community area in large scale and contains a set of instructions and graphics, as follows:
- Locate your property on the map.
- Determine the flood stage which will affect you. Consider not only water on your property, but also water preventing your evacuation.
- Listen for forecasts on the radio and television of stages at the stream gage used on the map.
- If the forecasted stage could affect you, begin emergency actions. If not, listen for revised forecasts until waters recede.
EXAMPLE: If you live in House A, river stages greater than 24 feet [indicated as 24 on the map] would affect your property directly. If your evacuation route goes through a low-lying area, emergency action may be required at a lower stage than the stage affecting your property.
back to topSusquehanna River Basin Flood Facts
- The Susquehanna River Basin comprises less than 1% of the land area of the continental United States, but experiences 6% of the national average flood damages.
- Damages from flood-related events total an average of $113 million per year in 1993 dollars.
- About 30% of the basin's population (1.12 million people) live along major rivers.
- About 1,160 of the 1,400 communities in the basin are in flood-prone areas.
- Pennsylvania, which comprises 74% of the basin, has more streams and tributaries than any other state in the continental United States.
- Local flooding occurs every year and major devastating floods along the main river hhappen on an average of once every 20 years.
- 1972 - the year of Hurricane Agnes - is the wettest year on record for the basin. 1996 is the second wettest year on record for the basin, when rain and snowfall caused several flooding events throughout the year.
Training Available
SRBC is offering training on local flood stage forecast maps to any local government, community, business, or citizen group interested. There is no registration fee for this training.
For further information, please contact SRBC at the following address:
Susquehanna River Basin Commission, 1721 N. Front St., Harrisburg, PA 17102
back to topAvailable Flood Stage Forecast Maps
Maps for areas marked with an * are available from the U.S. Army Corps of Engineers.
|
Municipality
|
County
|
Coverage
|
Reach
|
|
|
|
Full or Partial
|
|
| Pennsylvania |
|
|
|
| Allison Twp. | Clinton |
P
| Jersey Shore-Lock Haven |
| Athens Boro. | Bradford |
F
| Athens-Sayre-Susquehanna River and Chemung River |
| Athens Twp. | Bradford |
F
| Athens-Sayre-Susquehanna River and Chemung River |
| Bald Eagle Twp. | Clinton |
P
| Jersey Shore-Lock Haven |
| Bloomsburg Town | Columbia |
F
| Town of Bloomsburg |
| Brady Twp. | Lycoming |
F
| Turbot Twp. To Lycoming County |
| Buffalo Twp. | Perry |
P
| Upper Paxton |
| Buffalo Twp. | Union |
P
| Winfield to Lewisburg |
| Burnham Boro. | Mifflin |
F
| Lewistown-Juniata/Kischocoquillas |
| Castania Twp. | Clinton |
P
| Jersey Shore-Lock Haven |
| Chapman Twp. | Clinton |
*
| * |
| Clinton Twp. | Lycoming |
P
| Turbot Twp. To Lycoming County |
| Columbia Boro. | Lancaster |
F
| Lower Susquehanna |
| Conyngham Twp. | Luzerne |
P
| Shickshinny |
| Danville Boro. | Montour |
F
| Danville |
| Delaware Twp. | Northumberland |
F
| Turbot Twp. To Lycoming County |
| Derry Twp. | Dauphin |
F
| Harrisburg-Swatara Cr. And Backwater |
| Derry Twp. | Mifflin |
F
| Lewistown-Juniata/Kischocoquillas |
| Duboistown Boro. | Lycoming |
*
| * |
| Duryea Boro. | Luzerne |
F
| Wyoming Valley |
| East Buffalo Twp. | Union |
F
| Winfield to Lewisburg |
| East Chillisquaque Twp. | Northumberland |
P
| Winfield to Lewisburg |
| East Donegal Twp. | Lancaster |
P
| Lower Susquehanna |
| East Hanover Twp. | Dauphin |
F
| Harrisburg-Swatara Cr. |
| East Manchester Twp. | York |
P
| York-Condorous Cr. |
| East Pennsboro Twp. | Cumberland |
F
| Twp. Of East Pennsboro-River and Conodoquinet Cr. |
| Exeter Boro. | Luzerne |
F
| Wyoming Valley |
| Fairfield Twp. | Lycoming |
*
| * |
| Fairview Twp. | York |
F
| Yellow Breeches |
| Flemington Boro. | Clinton |
F
| Jersey Shore-Lock Haven |
| Forty Fort Boro. | Luzerne |
F
| Wyoming Valley |
| Gamble Twp. | Lycoming |
*
| * |
| Gregg Twp. | Union |
F
| Turbot Twp. To Lycoming County |
| Harrisburg City | Dauphin |
*
| * |
| Hellam Twp. | York |
P
| Lower Susquehanna/Long Level Area-York County |
| Hepburn Twp. | Lycoming |
*
| * |
| Hershey Village (Derry Twp.) | Dauphin |
F
| Harrisburg-Swatara Cr. |
| Hughesville Boro. | Lycoming |
*
| * |
| Hummelstown Boro. | Dauphin |
F
| Harrisburg-Swatara Cr. |
| Jenkins Twp. | Luzerne |
F
| Wyoming Valley |
| Jersey Shore Boro. | Lycoming |
*
| * |
| Kelly Twp. | Union |
F
| Winfield to Lewisburg/Turbot Twp. To Lycoming County |
| Kingston Boro. | Luzerne |
P
| Wyoming Valley |
| Leidy Twp. | Clinton |
*
| * |
| Lewis Twp. | Lycoming |
*
| * |
| Lewisburg Boro. | Union |
F
| Winfield to Lewisburg |
| Lewistown Boro. | Mifflin |
F
| Lewistown-Juniata/Kischocoquillas |
| Lisburn Village (Lower Allen Twp.) | Cumberland |
F
| Yellow Breeches |
| Liverpool Boro. | Perry |
F
| Upper Paxton |
| Liverpool Twp. | Perry |
F
| Upper Paxton |
| Lock Haven City | Clinton |
*
| * |
| Londonderry Twp. | Dauphin |
F
| Harrisburg-Swatara Cr. And Backwater |
| Long Level Area | York |
F
| Long Level Area-York County |
| Lower Allen Twp. | Cumberland |
F
| Yellow Breeches |
| Lower Augusta Twp. | Northumberland |
P
| Sunbury to Selingsgrove |
| Lower Mahanoy Twp. | Northumberland |
P
| Upper Paxton |
| Lower Swatara Twp. | Dauphin |
F
| Harrisburg-Swatara Cr. And Backwater |
| Lower Windsor Twp. | York |
P
| Long Level Area-York County |
| Loyalsock Twp. | Lycoming |
*
| * |
| Lycoming Twp. | Lycoming |
*
| * |
| Mahoning Twp. | Montour |
P
| Danville |
| Manchester Twp. | York |
F
| York-Condorous Cr. |
| Marietta Boro. | Lancaster |
F
| Lower Susquehanna |
| Middletown Boro. | Dauphin |
F
| Harrisburg-Swatara Cr. And Backwater |
| Mill Hall Boro. | Clinton |
F
| Jersey Shore-Lock Haven |
| Millersburg Boro. | Dauphin |
F
| Upper Paxton |
| Milton Boro. | Lycoming |
*
| * |
| Milton Boro. | Northumberland |
*
| * |
| Monoghan Twp. | York |
F
| Yellow Breeches |
| Monroe Twp. | Snyder |
F
| Sunbury to Selingsgrove |
| Montgomery Boro. | Lycoming |
*
| * |
| Montoursville Boro. | Lycoming |
*
| * |
| Muncy Boro. | Lycoming |
*
| * |
| Muncy Creek Twp. | Lycoming |
*
| * |
| New Cumberland Boro. | Cumberland |
F
| Yellow Breeches |
| Newton Twp. | Lackawanna |
F
| Wyoming Valley |
| North York Boro. | York |
F
| York-Condorous Cr. |
| Noyes Twp. | Clinton |
*
| * |
| Old Lycoming Twp. | Lycoming |
*
| * |
| Penn Twp. | Snyder |
P
| Sunbury to Selingsgrove |
| Piatt Twp. | Lycoming |
*
| * |
| Pittston Boro. | Luzerne |
F
| Wyoming Valley |
| Plains Twp. | Luzerne |
F
| Wyoming Valley |
| Point Twp. | Northumberland |
P
| Winfield to Lewisburg/Danville |
| Ransom Twp. | Lackawanna |
F
| Wyoming Valley |
| Renovo Boro. | Clinton |
*
| * |
| Riverside Boro. | Northumberland |
F
| Danville |
| Royalton Boro. | Dauphin |
F
| Harrisburg-Swatara Cr. And Backwater |
| Rush Twp. | Northumberland |
P
| Danville |
| Sand Beach Village | Dauphin |
F
| Harrisburg-Swatara Cr. |
| Sayre Boro. | Bradford |
F
| Athens-Sayre-Susquehanna River and Chemung River |
| Selingsgrove Boro. | Snyder |
F
| Sunbury to Selingsgrove |
| Shamokin Dam Boro. | Snyder |
F
| Sunbury to Selingsgrove |
| Shickshinny Boro. | Luzerne |
F
| Shickshinny |
| South Hanover Twp. | Dauphin |
F
| Harrisburg-Swatara Cr. |
| South Renovo Boro. | Clinton |
*
| * |
| South Waverly Boro. | Bradford |
F
| Athens-Sayre-Susquehanna River and Chemung River |
| Spring Garden Twp. | York |
P
| York-Condorous Cr. |
| Springettsbury Twp. | York |
F
| York-Condorous Cr. |
| Sunbury City | Northumberland |
F
| Sunbury to Selingsgrove |
| Swatara Twp. | Dauphin |
F
| Harrisburg-Swatara Cr. |
| Swoyersville Boro. | Luzerne |
F
| Wyoming Valley |
| Turbot Twp. | Northumberland |
F
| Turbot Twp. To Lycoming County |
| Union Deposit Village | Dauphin |
F
| Harrisburg-Swatara Cr. |
| Union Twp. | Union |
P
| Winfield to Lewisburg |
| Upper Allen Twp. | Cumberland |
F
| Yellow Breeches |
| Upper Augusta Twp. | Northumberland |
P
| Sunbury to Selingsgrove |
| Upper Fairfield Twp. | Lycoming |
*
| * |
| Upper Paxton Twp. | Dauphin |
F
| Upper Paxton |
| Watsontown Boro. | Northumberland |
F
| Turbot Twp. To Lycoming County |
| West Chillisquaque Twp. | Northumberland |
F
| Winfield to Lewisburg/Turbot Twp. To Lycoming County |
| West Fairview Boro. | Cumberland |
F
| Twp. Of East Pennsboro-River and Conodoquinet Cr. |
| West Hempfield Twp. | Lancaster |
F
| Lower Susquehanna |
| West Manchester Twp. | York |
P
| York-Condorous Cr. |
| West Pittston Boro. | Luzerne |
F
| Wyoming Valley |
| West Wyoming Boro. | Luzerne |
F
| Wyoming Valley |
| West York Boro. | York |
F
| York-Condorous Cr. |
| White Deer | Union |
F
| Turbot Twp. To Lycoming County |
| White Deer Twp. | Union |
F
| Turbot Twp. To Lycoming County |
| Williamsport City | Lycoming |
*
| * |
| Winfield | Union |
F
| Winfield to Lewisburg |
| Wolf Twp. | Lycoming |
*
| * |
| Wormleysburg Boro. | Cumberland |
P
| Twp. Of East Pennsboro-River |
| Wrightsville Boro. | York |
F
| Lower Susquehanna/Long Level Area-York County |
| Wyoming Boro. | Luzerne |
F
| Wyoming Valley |
| York City | York |
F
| York-Condorous Cr. |
|
|
|
|
|
| Maryland |
|
|
|
| Havre de Grace City | Harford |
F
| Conowingo Dam to Havre de Grace |
| Perryville Town | Cecil |
F
| Conowingo Dam to Havre de Grace |
| Port Deposit District | Cecil |
F
| Conowingo Dam to Havre de Grace |
| Port Deposit Town | Cecil |
F
| Conowingo Dam to Havre de Grace |
| New York |
|
|
|
| Addison Town | Steuben |
P
| Addison |
| Addison Village | Steuben |
F
| Addison |
| Barker Town | Broome |
*
| * |
| Bath Village | Steuben |
*
| * |
| Big Flats Town | Chemung |
F
| Big Flats |
| Big Flats Town | Chemung |
*
| * |
| Binghamton City | Broome |
F
| Binghamton-Susquehanna River and Chenago River |
| Campbell Town | Steuben |
*
| * |
| Chemung Town | Chemung |
P
| Athens-Sayre-Chemung River |
| Chenango Town | Chenango |
*
| * |
| Cohocton Town | Steuben |
*
| * |
| Conklin Town | Broome |
*
| * |
| Dickinson Town | Broome |
F
| Binghamton-Chenango River |
| Elmira City | Chemung |
F
| Newtown Cr. |
| Elmira City | Chemung |
*
| * |
| Elmira Heights Village | Chemung |
F
| Newtown Cr. |
| Elmira Town | Chemung |
F
| Newtown Cr. |
| Endicott Village | Broome |
F
| Binghamton-Susquehanna River |
| Erwin Town | Steuben |
*
| * |
| Fenton Town | Broome |
*
| * |
| Greene Town | Chenango |
*
| * |
| Horseheads Town | Chemung |
F
| Newtown Cr. |
| Horseheads Village | Chemung |
F
| Newtown Cr. |
| Johnson City Village | Broome |
F
| Binghamton-Susquehanna River |
| Kirkwood Town | Broome |
*
| * |
| Owego Village | Tioga |
F
| Owego |
| Port Dickinson Village | Broome |
F
| Binghamton-Chenango River |
| Southport Town | Chemung |
*
| * |
| Union Town | Broome |
F
| Binghamton-Susquehanna River |
| Vestal Town | Broome |
F
| Binghamton-Susquehanna River |
