National Hydrography Dataset (NHD) Flowlines


NHD Flowlines consist of routes that make up a linear surface water drainage network. Flowlines have a reach code and a measure, allowing for the establishment of upstream/downstream relationships. This network allows for powerful analysis and modeling capabilities. Each Feature type is attributed with descriptive information by an Fcode.


The NHD was created to assist scientists in modeling hydrologic features and is also useful for cartographic mapping purposes. The geometric features that came from the USGS DLG files, combined with the flow direction, reach codes, and other attributes taken from the EPA RF3 file, make the NHD a powerful modeling tool.

Time Period of Content

  • Beginning date: 1990s
  • Ending date: 2016

Publish Date



USGS, Florida Water Management Districts, Florida Department of Environmental Protection


Florida Department of Environmental Protection

Theme Keywords

hydrography, water, lakes, streams, rivers, estuaries

Place Keywords


Source Scale


Horizontal Accuracy

Estimated to meet 1:24,000 National Map Accuracy Standards (+/- 40 feet)

Vertical Accuracy

If the source for elevation is 7.5 minute topo map, estimated to be one half of a contour, or +/- 2.5 feet.

Process Steps


ESRI File Geodatabase

Format Details


Albers Florida HARN

Field Names

permanent_identifier = Unique ID

fdate = Date of last feature modification.

resolution = Source resolution. All values = 2

Code   Description1   Description2
1 Local >1:12,000
2 High 1:24,000/12,000
3 Medium 1:100,000

gnis_id = USGS Geographic Names Information System (GNIS) ID

gnis_name = USGS Geographic Names Information System (GNIS) Name


reachcode = Unique identifier composed of two parts. The first eight digits is the subbasin code as defined by FIPS 103. The next six digits are randomly assigned, sequential numbers that are unique within a subbasin, length 14.

flowdir = Direction of flow relative to coordinate order.


ftype = 3-digit feature code. (Integer)

Code   Description
334   Connector
336   Canal/Ditch
420   Underground Conduit
428   Pipeline
460   Stream / River
558   Artificial Path
566   Coastline

fcode = 5-digit feature code. Extra two digits provide a more detailed description of the feature. (Integer)

enabled = Created when Geometric Network is built. All features should be set to True. New or modified features will have a Null value until network is rebuilt.


Distribution Info