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Service Description: This REST service endpoint features dam and dam break inundation zone data, including data as of Q3 of 2025 (last updated 10/9/2025).
The REST service contains the following layers:
- Dam Points
- Dam Break Inundation Zones (Simple, Detailed)
- Dam Watersheds
Depending on viewing scale, the map service will automatically toggle layers and alternate symbology for better viewing and performance. At smaller scales, only dam points will render, at medium scales simple inundation extents will render, and at larger scale view detailed inundation zones will render with all flood scenarios.
Dam Break Inundation Zones: The Dam Break Inundation Zone layer contains flood extent data in polygon format submitted to DCR by professional engineers. Please note that due to the detailed nature of DBIZs, the file size and vertex count are large, which can cause slow performance and display. A simplified DBIZ layer is available which will display significantly faster, and may be more suitable for web viewing purposes.
The data dictionary for the flood "Type" field is as outlined below:
- PMF - Probable Maximum Flood
- PMFwBr - Probable Maximum Flood with Breach
- SDF - Spillway Design Flood (Based on hazard class this can be 100-year, 0.5 PMP, 0.9 PMP. However, it can also be different based on an IDA. Please refer to the inundation study report in DSIS to determine precipitation values)
- SDFwBr - Spillway Design Flood with Breach
- SunDayBr - Sunny Day Breach.
Dam break inundation studies have not been completed for all Virginia dams, and not all studies completed in the past provided GIS inundation zones. At the time of publishing 574 dams have GIS DBIZ with a total of 1,901 flood scenarios.
Map Name: Map
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Dynamic Legend
Dynamic All Layers
Layers:
Description:
Service Item Id: 743fccc5fb1341e3b37a7757f4d3d69b
Copyright Text: Virginia Department of Conservation and Recreation
Spatial Reference:
102100
(3857)
Single Fused Map Cache: false
Initial Extent:
XMin: -8999887.13733938
YMin: 4352537.592448666
XMax: -8420779.037676033
YMax: 4752170.041389902
Spatial Reference: 102100
(3857)
Full Extent:
XMin: -9305834.6065
YMin: 4316846.298100002
XMax: -8398267.4748
YMax: 4808455.876900002
Spatial Reference: 102100
(3857)
Units: esriMeters
Supported Image Format Types: PNG32,PNG24,PNG,JPG,DIB,TIFF,EMF,PS,PDF,GIF,SVG,SVGZ,BMP
Document Info:
Title: Map
Author:
Comments:
Subject:
Category:
Keywords: Dam Safety, dam break inundation zones, dbiz, dam, dam break, virginia, inundation
AntialiasingMode: Fast
TextAntialiasingMode: Force
Supports Dynamic Layers: true
Resampling: false
MaxRecordCount: 2000
MaxImageHeight: 4096
MaxImageWidth: 4096
Supported Query Formats: JSON, geoJSON, PBF
Supports Query Data Elements: true
Min Scale: 0
Max Scale: 0
Supports Datum Transformation: true
Child Resources:
Info
Dynamic Layer
Supported Operations:
Export Map
Identify
QueryLegends
QueryDomains
Find
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