U.S. Geological Survey
U.S. Geological Survey
USEPA Reach File 1 converted to Arc/INFO
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APPENDIX A -- EPA REACH FILE MANUAL
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REACH FILE MANUAL
U.S. Environmental Protection Agency
Written by:
C. Robert Horn
June 30, 1986
(NOTE: The original Reach File Manual is out of print. This file was
typed from a copy of the original manual in October, 1994. The author
reviewed the manual and suggested minor changes and corrections,
which were incorporated. Mr Horn's address is: CDP Corp., 42 6th Street,
Apalachicola, FLorida, 32320, phone 904-653-2074.)
CONTENTS
Introduction
Present Status
Reach File Description
Reach File Directory
INTRODUCTION
The Reach File, EPA's national database of surface water features,
plays five roles in support of water programs:
* It provides names and latitude/longitude coordinates and other
identifiers and locators of streams and other surface water features of the
nation.
* It combines USGS basin codes with EPA reach numbers to form a unified
surface water classification system which may be used to integrate water
databases for common analyses within an hydrologic framework.
* It provides hydrologic structure to the computer representation of
surface waters in a manner needed for water quality modeling and database
traversals of streams and waterbodies in hydrological order.
* It provides data for graphical displays of streams, lakes,
reservoirs, estuaries, and other surface water features throughout the
nation in connection with water quality analysis and reporting.
* It provides information on the characteristics of streams, water
bodies, and watersheds to aid in water quality analysis and reporting.
Various other water resource databases have been linked with the
Reach File to provide combined analyses of water supplies, hydrology, water
quality standards, and pollutant sources. It has been installed by OWRS in
the STORET system and by OWPO in the COGENT system. Other EPA offices,
including OTS and ORD, are using the file to help meet several other
objectives.
PRESENT STATUS
Complete structure and trace for contiguous U.S. for 68,000 reaches
(700,000 miles of stream). Update to add reaches named on 71/2 minute
maps is underway.
Various record types are included in the Reach File. The Hydrologic
Structure record type (TABLE A) is complete for all reaches except for new
data elements which have recently been added to this record type in byte
positions 518 and greater. The Reach Trace record type (TABLE B) is
complete for more than 95% of all reaches. The Reach Characteristics
record type for transport reaches is complete for all data elements checked
in TABLE C. The Open Waterbody Characteristics record type is not
available at this time (TABLE D). The data elements checked in TABLE E are
available for all cataloging units in the contiguous United States.
REACH FILE DESCRIPTION
1. Transport Reaches and Shoreline Reaches
The basic building block of the Reach File is the reach, which is a
distinctly identified lineal element. There are two types of reaches in
the file: shoreline reaches and transport reaches. Shoreline reaches
depict the U.S. continental coasts and the perimeters of lakes, reservoirs,
and estuaries, and the shorelines of some wide rivers and islands.
Transport reaches depict segments of the hydraulic transport paths through
streams and inland open waters including lakes and estuaries. Generally,
the transport reaches extend from one stream junction to another. They are
linked in a skeletal structure which represents the branching patterns of
surface water drainage from all tributaries progressively in the downstream
direction. This order also facilitates retrievals of surface water related
data throughout all hydraulic transport paths represented in the file in
both the upstream and downstream directions. Other surface water files may
be related to each other in hydrologic order by using the Reach File in
conjunction with Reach File reach number placed in those other files.
2. Interconnection Between Reaches
Within the file, no more than two transport reaches may be connected
to either end of a given transport reach. As illustrated below, these
points of connection are either convergent, divergent, or simple.
Convergent Divergent Simple
For transport reaches, convergent junctions connect two streamflow
input reaches with one output reach, divergent junctions connect one input
reach with two output reaches, and simple junctions connect one input reach
with one output reach. For shoreline reaches, the head of one shoreline
reach is connected to the foot or "base" of the next. The shoreline reach
connected to the head of another shoreline reach is identified within that
other shoreline reach record in the "upstream left" reach fields (cols 266-
281, Table A). The "upstream right" field of a given shoreline reach is
reserved for the reach number of the transport reach (if one exists) that
connects by its downstream end to the head of that shoreline reach.
Convergent, divergent, and simple connections are defined within each
transport reach record using reach numbers for upstream left and right
reaches, and downstream and complement reaches as illustrated below for
reach 01020304-016-00.00 (showing two convergent connections).
3. Reach File Record Types
The Reach File contains many data elements, i.e., data types, which
may be grouped in various ways to form a variety of record types to best
satisfy specific applications. For example, under a database management
system of hierarchical design, one office has placed the Reach File reach
numbers, hydrologic sequence numbers, stream names, and all the data which
define the interconnections between reaches in one file, the Reach File
streamflow estimates in a different file associated with stream gages, and
the digitized traces of reaches in a file of state and county boundaries.
Other database managers may need to provide for analyses which require
more complex relationships than are readily established in sequential (one-
to-one) or hierarchical (one-to-many) database management systems. The so-
called relational or network (many-to-many) database management systems
are likely to become the best systems for Reach File applications as the
demand for relating more and more data types from many offices increases,
especially where ultimate applications are vastly different but
nevertheless share some data. Regardless of the different data
relationships that are possible in actual applications, the master Reach
File is maintained as a system of five record types, within each of which
the data types are related in some sense. These relationships are
primarily associated with the techniques used in assembling each record
type and are not expected to be explicitly retained by recipients of copies
of the master Reach file. The five record types are maintained in the
master Reach File as five separate sequential files as follows:
o Hydrologic Structure Record Type: The Hydrologic Structure Record
Type contains all the data types identified in Table A, and are
described in Sections 4 through 17 below.
o Reach Trace Record Type: The Reach Trace Record Type contains a
reach number, a count of the coordinates in the record, and the
list of latitude/longitude coordinates along each reach.
These records, as described in Table B, are in vector form for
producing maps of the reaches.
o Reach Characteristics Record Type: This record type contains
data elements, listed in Table C, intended to help characterize
each reach with respect to its physical attributes such as
streamflow, stream velocity, slope, channel geometry, bottom
characteristics, temperature, etc.
o Open Waterbody Characteristics Record Type: This record type
contains data elements, listed in Table D, intended to describe
whole waterbodies such as lakes, reservoirs, ponds, estuaries,
bays, etc., with estimates of surface area, depth, open water
body type codes, latitude/longitude coordinates, water use,
temperature, etc.
o Hydrologic Unit Characteristics Record Type: This record type
contains watershed information, illustrated in Table E, most
especially various information about each cataloguing unit, such
as watershed area, land uses, total stream miles, precipitation,
runoff, mean elevation, land surface form, etc.
4. Reach Numbers
Reach numbers are the unique identifiers of transport reaches and
shoreline reaches; they consist of eleven digits. Provision is made for
subdividing reaches at points such as points of confluence between a reach
already present in the file and a new tributary being added to the file.
When a reach is subdivided, each of its pieces is referred to as a subreach
and is uniquely identified by an extension of the reach number. This
extension is a four digit fixed decimal number with two digits to the left
and two digits to the right of the decimal point. As shown below, they are
constructed to include a USGS eight-digit cataloguing unit code, a three-
digit segment number, and a four-place fixed decimal number.
CU: An eight-digit USGS Cataloguing Unit Code that identifies the
basin in which the reach resides.
SEG: A three-digit segment number. This number, in combination with
the CU number, forms an eleven-digit number, called a reach
number, which uniquely identifies a reach within the U.S.
MI: This number is a mile point which identifies a
subreach within a reach; in combination with the
reach number it forms a fifteen digit number which
uniquely identifies a subreach within the U.S.
The value of this number is the distance measured
from the base of the reach to the base of the
subreach being identified within that reach. The
"base" of a transport reach or subreach is its
downstream end. However, since downstream
generally has no meaning with respect to
shorelines, the term "base" as applied to
shorelines, is defined in terms of a counter-
clockwise traversal along the shoreline about any
point in the open water near the shoreline. For
shoreline reaches and subreaches, the base is the
end at which this type of counter-clockwise
traversal begins. Above this base point, at some
location on the shoreline, and at a point further
along in the counter-clockwise traversal, is the
head of the shoreline reach or subreach. The base
of a shoreline reach is analogous to the
downstream end of a transport reach, and the head
of a shoreline reach is analogous to the upstream
end of a transport reach. Viewing the
consequences of this counter-clockwise rule from a
global perspective looking down on the planet,
shoreline reaches are connected counter-clockwise
in a daisy chain around a lake, whereas they are
connected clockwise around an island or the
continent. This rule provides users with the
ability to determine in which direction to search
along a shoreline to find the base of a given
shoreline reach or subreach, without having to
refer to a map of more global coverage.
For transport reaches and shoreline reaches, it
should be noted that the value assigned to MI is
zero for the subreach whose base is connected to
the base of the reach within which the subreach is
located. Each reach contains at least one
subreach; a subreach is coextensive with its reach
if it is the only one within that reach. An
additional reach is placed within a given reach
when the reach is subdivided to identify a point
of confluence with a tributary, a point of entry
to, or exit from, a lake or other open water, or a
point at which a significantly large local change
in slope, velocity, or flow occurs. All such
subdivisions, when included in the file, introduce
subreaches within the file. In accordance with
Reach File management policy, reach numbers will
not be changed to accommodate the introduction of
new reaches within the file; however, the MI
values may be changed. Thus, subreach numbers are
not permanent.
Additional reaches which are altogether new and not part of a reach
already in the file, may be added to a cataloging unit in order to define
surface waters not previously identified in the Reach File. The reach
numbers for these reaches are made up of the cataloging unit number and a
new three-digit segment number not used elsewhere in that cataloging unit.
The subreach within each of these reaches will be coextensive with its
parent reach until it is subdivided. All new reaches which are tributary
to pre-existent reaches, fall into this category.
5. Reach Numbers of the Connected Reaches
Throughout the rest of this document, the term "reach" will mean
"transport reach," unless it is explicitly qualified as a shoreline reach.
The following data elements are used in the Reach File to identify all
possible reaches connected to any given reach:
DSCU, DSSEG, DSMI: The CU, SEG, and MI, respectively,
of the reach downstream of the immediate reach.
The downstream reach is the reach into which the
immediate reach flows, except that if the
downstream end of the immediate reach is a
divergent junction, then the reach identified as
the downstream reach is the major recipient of the
outflow from the immediate reach, whereas in this
case, the reach identified as the complement is
the recipient of the minor portion of that flow.
CCU, CSEG, CMI: The CU, SEG, and MI, respectively, of
the complement reach. The complement is the reach
that flows into the same junction as the immediate
reach, except that if the downstream end of the
immediate reach is a divergent junction, then
CCU, CSEG, and CMLPT identify the reach which is
the minor recipient of the outflow from the
immediate reach.
CDIR: The complement direction. Looking downstream,
this is the left or right (L or R) side of the
immediate reach to which the complement is
connected.
ULCU, ULSEG, ULMI: The CU, SEG, and MI, respectively,
of the reach upstream and to the left of the
immediate reach, looking upstream.
URCU, URSEG, URMI: The CU, SEG, and MI, respectively,
of the reach upstream and to the right of the
immediate reach, looking upstream.
6. Stream Levels
Each reach is assigned a stream level which may be used to define the
hierarchical relationship between streams and tributaries in a given
drainage network. A tributary to a given stream is always one level higher
than the stream into which it flows. For instance, the Mississippi River
is a level-one stream, the Ohio River is a level-two stream, and the
Tennessee River is a level-three stream. Stream levels are useful in the
retrieval algorithms which traverse the Reach File. A "level path" can be
followed to identify all mainstem reaches of a given river. For instance,
the mainstem of the Mississippi River can be readily identified by
retrieving all level-one reaches upstream of the Mississippi River
terminus.
There are several variables in the file associated with stream levels,
as described below:
LEV: The stream level of the immediate reach.
Shoreline segments are assigned a level of zero.
J: The junction code pertaining to the junction at
the downstream end of the immediate reach. In the
case of a convergent junction, this is equal to
the level of the reach downstream of the immediate
reach. For simple junctions and divergent
junctions this variable is assigned the value of
zero; likewise, the J value for any shoreline
reach is zero.
TRMBLV: The terminal base level: the level of the
terminal reach of the stream system to which the
immediate reach belongs. Terminal reaches are
assigned levels according to the manner in which
the streams terminate, as follows:
TRMBLY Description
1 Stream outlet is Atlantic, Pacific, or
Gulf of Mexico;
2 Stream outlet is one of the Great Lakes,
or the Great Salt Lake;
3 Stream exits from U.S. into Canada or
Mexico;
4 Isolated drainage (flows into the
ground).
7. Sequence Numbers
The Reach File is designed for routing in a specific hydrologic
sequence; the sequence numbers ascend in that order. The most upstream
reach in a given basin is assigned the lowest sequence number in that
basin; the sequence progresses to the reach downstream of a given reach
only after having been progressively incremented and assigned to all
reaches upstream of that downstream reach. Each reach in the file is
assigned a unique hydrologic sequence number. The update process will
occasionally change these sequence numbers when new reaches are added to
the file, or when some reaches are possibly deleted from it. Thus,
sequence numbers will be allowed to be changed even though, as a rule,
reach number changes are not allowed.
SEQNO: An eleven (11) digit hydrologic sequence
number: reaches are processed in SEQNO order for
routing through reaches identified in the File.
The first five (5) digits constitute the primary
sequence number and the last six (6) digits are
used for inserting new reaches into the File
without having to change the primary sequence
numbers in most instances. The sequencing begins
at the most upstream reach of the lowest level
stream in a given Cataloging Unit. The next reach
in the sequence is either the reach downstream
from the first reach, or if there is a tributary
to that downstream reach other than the first
reach, the next reach is the most upstream reach
on that tributary steam. There are no duplicate
sequence numbers in the Reach File.
Each reach record also contains SEQNO's for other reaches in the File
as defined below:
DSSEQ: The SEQNO of the reach directly downstream of
the immediate reach; in the case of a divergent
junction at the downstream end of the immediate
reach, this is the SEQNO of the reach which is
the major recipient of flow from the immediate
reach.
USSEQ: The SEQNO of the reach directly upstream of the
immediate reach and at the same level as the
immediate reach.
STRTSQ: The SEQNO of the start reach of the same level
path as the immediate reach.
STOPSQ: The SEQNO of the most downstream reach on the
same level path as the immediate reach.
An additional variable is given in conjunction with the USSEQ:
USDIR: Looking upstream, this is the left or right (L
or R) side of the immediate reach to which the
USSEQ reach is connected.
8. Reach Types
The term "reach type", not to be confused with any of the Reach File
record types, refers to a one-character code which had been assigned to
each reach to categorize transport reaches and shoreline reaches as
follows:
A Artificial Lake Reach (A transport reach).
An artificial reach within a lake or reservoir
inserted in the file to provide connection between
input and output reaches of the open water.
B Bi-directional Reach (A transport reach).
A reach for which the direction of flow is
ambiguous.
D Dam Reach (A transport reach).
A reach which is a dam through which water flows.
this is a transport reach (RFLAG=1); its primary
and open water names are same as for next reach
upstream on same level. Head change is given in
SPEC1 as feet.
E Entry Reach (A transport reach).
A reach which receives flow from Canada or Mexico.
F Falls Reach (A transport reach).
A reach which is either a waterfall, drop
spillway, or a reach of rapids. Head change is
given in SPEC1 as feet.
M Artificial Open Water Reach (A transport reach).
An artificial reach within any open water, other
than a lake or reservoir, to provide connection
between input and output reaches of the open
water.
N Non-Connected Reach (A transport reach).
A reach not having codes to link it to other
reaches.
R Regular Reach (A transport reach).
A reach which has upstream and downstream reaches
connected to it and which is not classified as
another type of reach.
S Start Reach (A transport reach).
A headwater reach which has no reaches above it in
the reach file. This type of reach has either one
or two reaches connected to its downstream end.
T Terminal Reach (A transport reach).
A reach downstream of which there is no other
reach (for example, a reach which terminates into
an ocean, a land-locked lake, or the ground).
This type of reach has either one or two reaches
connected to its upstream end.
V Open Water Terminal Reach (A transport reach).
A reach which is both a terminal reach and an
artificial open water reach.
X Terminal Start Reach (A transport reach).
A reach which is both a terminal reach and a start
reach.
Z Terminal Entry Reach (A transport reach).
A reach which is both a terminal reach and an
entry reach.
C Continental Shoreline Segment (A shoreline reach).
G Great Lakes Shoreline Segment (A shoreline reach).
I Island Shoreline Segment (A shoreline reach).
L Lake Shoreline Segment (A shoreline reach).
A segment which follows the shoreline of a lake
other than the Great Lakes.
W Wide-River Shoreline Segment (A shoreline reach).
9. Routing Flags
Each reach has four (4) one-character flags which can be used in
various routing schemes. The flags take values of 0 or 1, corresponding to
"no" or "yes", respectively. Only transport reaches can have routing flag
values of 1. The four flags are defined below:
RFLAG - Transport reach Flag:
0 = Reach is not a transport reach.
1 = Reach is a transport reach.
OWFLAG - Open Water Flag.
0 = Reach is not an artificially constructed reach in
a lake, reservoir, wide river, bay, or other open
water.
1 = Reach is an artificially constructed reach in open
water (types A, M, or V).
TFLAG - Terminal Flag:
0 = Reach is not a terminal reach.
1 = Reach is terminal (types T, V, X, Z).
SFLAG - Start Flag:
0 = Reach is not a start reach.
1 = Reach is a start reach (types S, X, E, Z).
10. Divergence Codes
Reaches which are connected to divergent junctions are categorized
with a one-digit divergence code. The inflowing reach is referred to as
the "input reach"; the outflowing reach receiving the majority of the flow
is the "major reach"; and the outflowing reach receiving the minority of
the flow is the "minor reach".
K: The one-digit divergence code used to classify
reaches connected to divergent junctions. The
possible values of K are described below:
K Value Definition
0 Not part of a divergent junction
1 Input reach where minor reach is
downstream left
2 Input reach where minor reach is
downstream right
3 Minor reach of a divergence
4 Combination of K values 1 and 3
5 Combination of K values 2 and 3
6 Major reach of a divergence
7 Combination of K values 1 and 6
8 Combination of K values 2 and 6
11. Reach Length
The following data elements are related to reach length:
SEGL: The length of the immediate reach measured to
the nearest tenth of a mile.
ARBSUM: Arbolate sum: the sum of the lengths, in
miles, of all digitized reaches upstream from the
base of the immediate reach, including all
branches of all streams above it. This gives an
indication of the size of the drainage system
upstream of the reach.
PMILE: Path mile: the distance, in miles, from the
downstream end of the immediate reach to the
terminus, as measured along the hydraulic
transport path. (A terminus is the downstream
point of a drainage system where a stream enters
an ocean, the ground, a land-locked lake, one of
the Great Lakes, or where it flows into Canada or
Mexico.)
12. Names and Name Codes
The name, or names, associated with a given reach may have a maximum
length of thirty (30) characters. Pseudo-names are included where reach
names could not be identified when the file was being developed in its
original form. Pseudo-names in all cases consist of an asterisk followed
by a single letter, e.g. "*A". These pseudo-names were developed in a
visual update using topographic maps to uniquely identify principle flow
paths and to establish stream levels for reach file users concerned with
hydrological analyses; pseudo-names were not provided for the
inconsequential purpose of simply insuring that every reach is named. An
automated process which would have been based on stream mileages was set
aside and not used, in favor of this visual technique. Each reach name has
an eleven (11)digit name code associated with it in order to uniquely
identify the surface water represented by the reach. Up to three different
names and name codes may be associated with a given reach:
PNAME, PNMCD: The primary name and name code,
respectively, associated with the reach. For
transport reaches, including open water reaches,
this is a stream name. For shoreline reaches,
this is the name of the open waterbody. Each
transport reach of a given stream level within an
open waterbody will bear the name of the stream
which feeds that open water reach and is at a
stream level equal to that open water reach. All
reaches of a given stream have been assigned the
same name and the same primary name code. Other
streams having that same name will have different
primary name codes. For example, a Back Creek in
Virginia would have a different PNMCD from any
other Back Creek in Virginia or any other State.
CNAME: CNMCD: Complement name and name code,
respectively. This is the primary name and
primary name code of the complement reach, if a
complement reach exists.
OWNAME, OWNMCD: Open water name and name code
respectively. For open water reaches (OWFLAG = 1)
this is the name of the lake or wide river in
which the reach resides.
GNMCD: Generic name code. A code given to all reaches
having the same primary name. All surface waters
with names which are spelled identically will have
the same GNMCD. For example, a Back Creek in
Virginia would have the same GNMCD as a Back Creek
in Montana.
13. TERMID: Terminal Stream System Identifier
Each terminal stream system in the Reach File has a unique 5-digit
code associated with it. This code can be used to readily identify all
reaches in, for example, the Potomac River Basin.
14. Latitude/Longitude Coordinates
There are numerous latitude/longitude coordinate pairs given in the
file for geographically-based retrieval and analysis. All
latitude/longitude data are given in decimal degrees to the nearest .0001
degree. A "skeleton" trace can be generated using the upstream, 3rd
quartile, midpoint, 1st quartile, and downstream latitude/longitude
coordinates, which are located in bytes 298-377 as shown in Table A.
Large-scale areal retrievals can be performed using the minimum and
maximum latitude/longitude pairs. These coordinates define the smallest
north-south/east-west rectangle containing the reaches.
MINLAT, MINLON, MAXLAT, MAXLON: North-south box window
coordinates. The largest and smallest latitudes
and longitudes found in the digitized trace of the
immediate reach.
TWLAT1, TWLNG1, etc. : Tucker Window coordinates. The
latitude/longitude coordinates of the four corners
of the smallest bounding rectangle for the
immediate reach. These rectangles are not
constrained to north-south alignment; they are
therefore smaller than the North-South box
windows.
15. State/County FIPS Codes
The state/county units associated with all digitized reaches have been
identified. Each of these is entered in terms of a five (5) digit FIPS
(Federal Information Processing Standards) Code. The following variables
relating to the FIPS codes are included in the File:
NSRCO: The number of distinct FIPS codes associated
with the reach. Up to 7 state-county codes may be
entered for a given reach.
SCFLAG: The state-county flag, which can take the
following values:
A - The reach is totally enclosed by one county,
B - At least one endpoint of the reach lies on
the border between counties,
C - The reach occupies more than one county and
neither endpoint of the reach lies on a
border between counties;
STCOA-STCO8: The 5-digit FIPS codes associated with
the reach. The first two (2) digits are the state
code and the last three digits are the county
code.
16. Date-of-Update Code
This code contains the date of the most recent update of the reach.
17. Subfile Start and Terminal Flags
SFSTRT, SFTERM: These flags indicate, in any arbitrary
subset of the Reach File, if a given reach has
been disconnected from its upstream or downstream
drainage system to form that subfile. If the
upstream end of a given reach is disconnected for
this purpose, then SFSTRT=1 and the immediate
reach may be handled similar to a Type-S or Type-X
reach. If the downstream end is disconnected
while creating the subfile, then SFTERM=1 and the
reach may be handled similar to a Type-T or Type-X
reach.
TABLE A
HYDROLOGIC STRUCTURE RECORD TYPE
(Data elements)
==========================================================================
Variable Columns Type(1) Length Description
--------------------------------------------------------------------------
*CU 1-8 I 8 Cataloging Unit
*SEG 9-11 I 3 Segment Number
*MI 12-16 F 5.2 Mile Point
*SEQNO 17-27 I 11 Sequence Number
*RFLAG 28 A 1 Reach Flag (0,1)
*OWFLAG 29 A 1 Open Water Flag 0,1)
*TFLAG 30 A 1 Terminal Flag (0,1)
*SFLAG 31 A 1 Start Flag (0,1)
*TYPE 32 A 1 Reach Type
*SEGL 33-37 F 5.1 Reach Length (mi.)
*LEV 38-39 I 2 Level
*J 40-41 I 2 Junction Number
*K 42 I 1 Divergence Code
*PMILE 43-50 F 8.1 Path Mile
*ARBSUM 51-58 F 8.1 Arbolate Sum
*DSSEQ 59-69 I 11 Downstream SEQNO
*USSEQ 70-80 I 11 Upstream SEQNO
*USDIR 81 A 1 Upstream Reach Direction (L or R)
*TERMID 82-86 I 5 Terminal Stream System Identifier
*TRMBLV 87 I 1 Terminal Base Level
*STRTSQ 88-98 I 11 Level Start SEQNO
*STOPSQ 99-109 I 11 Level Stop SEQNO
*PNAME 110-139 A 30 Primary Name
*PNMCD 140-150 I 11 Primary Name Code
*CNAME 151-180 A 30 Complement Name
*CNMCD 181-191 I 11 Complement Name Code
*OWNAME 192-221 A 30 Open Water Name
*OWNMCD 222-232 I 11 Open Water Name Code
*DSCU 233-240 I 8 Downstream CU
*DSSEG 241-243 I 3 Downstream SEG
*DSMI 244-248 F 5.2 Downstream MI
*CCU 249-256 I 8 Complement CU
*CSEG 257-259 I 3 Complement SEG
*CMI 260-264 F 5.2 Complement MI
*CDIR 265 A 1 Complement Direction (L or R)
*ULCU 266-273 I 8 Upstream Left CU
*ULSEG 274-276 I 3 Upstream Left SEG
*ULMI 277-281 F 5.2 Upstream Left MI
*URCU 282-289 I 8 Upstream Right CU
*URSEG 290-292 I 3 Upstream Right SEG
*URMI 293-297 F 5.2 Upstream Right MI
*ULAT 298-305 F 8.4 Upstream Latitude
*ULONG 306-313 F 8.4 Upstream Longitude
Q3LAT 314-321 F 8.4 Third Quartile
Q3LONG 322-329 F 8.4 Third Quartile Longitude
MDLAT 330-337 F 8.4 Midpoint Latitude
MDLONG 338-345 F 8.4 Midpoint Longitude
Q1LAT 346-353 F 8.4 First Quartile Latitude
Q1LONG 354-361 F 8.4 First Quartile Longitude
*DLAT 362-369 F 8.4 Downstream Latitude
*DLONG 370-377 F 8.4 Downstream Longitude
MINLAT 378-385 F 8.4 Minimum Latitude
MINLON 386-393 F 8.4 Minimum Longitude
MAXLAT 394-401 F 8.4 Maximum Latitude
MAXLON 402-409 F 8.4 Maximum Longitude
TWLATI 410-417 F 8.4 ----------------
TWLAG1 418-425 F 8.4 | |
TWLAT2 426-433 F 8.4 | |
TWLAG2 434-441 F 8.4 |Tucker Window |
TWLAT3 442-449 F 8.4 | Coordinates |
TWLAG3 450-457 F 8.4 | |
TWLAT4 458-465 F 8.4 | |
TWLAG4 466-473 F 8.4 ----------------
*NSTCO 474 I 1 Number of State/County Codes
*SCFLAG 475 A 1 State/county Flag
*STCO1 476-480 I 5 ----------------
STCO2 481-485 I 5 | |
STCO3 486-490 I 5 | |
STCO4 491-495 I 5 | State/County |
STCO5 496-500 I 5 | IPS Codes |
STCO6 501-505 I 5 | |
STCO7 506-510 I 5 ----------------
Reserved 511-515 I 5 n/a
DATECD 516-517 I 2 Date code (most recent update)
SFSTRT 518 A 1 Subfile Start Reach Flag (0,1)
SFTERM 519 A 1 Subfile Terminal Reach Flag (0,1)
*GNMCD 520-523 I 4 Generic Name Code
**CLASIF 524-525 I 2 Stream order classification
SPEC1 526-529 A 4 Parameter for special uses
SPEC2 530-533 A 4 Parameter for special uses
SPEC3 534-537 A 4 Parameter for special uses
(1) The format description for each field is defined as either ALPHA,
FIXED, or FLOAT. "A" expects alphanumeric characters to be left justified
within the specified columns. "I" expects integer numerics without a
decimal point, right justified in the specified columns. "F" expects a
real numeric typed with a decimal point located anywhere within the
specified columns.
TABLE B
REACH TRACE RECORD TYPE
The reach trace record contains a reach number, a count of the
coordinate pairs in the reach trace record, and the list of
latitude/longitude coordinates which define the trace of the reach. This
record type provides the trace data for both the transport reaches and the
shoreline reaches defined in the Reach File Description and Table A above.
The data elements and format for this record type are as follows:
(Data Elements)
=========================================================================
Variable Columns Type1 Length Description
-------------------------------------------------------------------------
*CU 1-8 I 8 Cataloging Unit
*SEG 9-11 I 3 Segment Number
*MI 12-16 F 5.2 Mile Point
*COUNT 17-20 I 4 Number of coordinate pairs
*LAT(1) 17-24 F 8.4 Latitude of base of reach
*LONG(1) 25-32 F 8.4 Longitude of base of reach
*LAT(2) 33-40 F 8.4 Latitude of 2nd point
*LONG(2) 41-48 F 8.4 Longitude of 2nd point
. .
. .
. .
. .
. .
*LAT(n-1) Latitude of next-to-last point
*LONG(n-1) Longitude of next-to-last point
*LAT(n) F 8.4 Latitude of head of reach
*LONG(n) F 8.4 Longitude of head of reach
TABLE C
REACH CHARACTERISTICS RECORD TYPE
(Data elements)
==========================================================================
Variable Description
--------------------------------------------------------------------------
*CU Cataloging Unit
*SEG Segment Number
*MI Mile Point
*DA Drainage Area (Sq.Mi)
IDA Incremental Drainage Area
*ELEUP Water Surface Elevation
*SLOPE Average slope of reach
XAREA Representative crossection
XATYPE (P)arabolic, (T)rapezoidal
*Q7LOW Low Flow
*Q1MEAN Mean Flow
*Q1JAN Mean Jan Flow
*Q1FEB Mean Feb Flow
*Q1MAR Mean Mar Flow
*Q1APR Mean Apr Flow
*Q1MAY Mean May Flow
*Q1JUN Mean Jun Flow
*Q1JUL Mean Jul Flow
*Q1AUG Mean Aug Flow
*Q1SEP Mean Sep Flow
*Q1OCT Mean Oct Flow
*Q1NOV Mean Nov Flow
*Q1DEC Mean Dec Flow
Q1PEAK2 2 year peak flow
Q1PEAK10 10 year peak flow
Q1PEAK50 50 year peak flow
T1MEAN Mean water temperature
T1JAN Mean Jan Temperature
T1FEB Mean Feb Temperature
T1MAR Mean Mar Temperature
T1APR Mean Apr Temperature
T1MAY Mean May Temperature
T1JUN Mean Jun Temperature
T1JUL Mean Jul Temperature
T1AUG Mean Aug Temperature
T1SEP Mean Sep Temperature
T1OCT Mean Oct Temperature
T1NOV Mean Nov Temperature
T1DEC Mean Dec Temperature
HMEAN Mean Hardness
HMED Median Hardness
HMAX Maximum Hardness
HMIN Minimum Hardness
H85TILE 85th Percentile Hardness
H15TILE 15th Percentile Hardness
TABLE D
OPEN WATERBODY CHARACTERISTICS RECORD TYPE
(Data elements)
(Terminology: WB means Waterbody, TSEG means Triangular Segment within WB)
===========================================================================
Variable Description
---------------------------------------------------------------------------
CU CU of principal outlet
SEG Seg of principal outlet
MI MI of principal outlet
WBTYPE Open Waterbody Type
WBDEPTH Mean depth of Waterbody
WBAREA Surface area of Waterbody
WBACC Accuracy code for WBAREA
WBLAT Latitude of Centroid of WB
WBLON Longitude of Centroid of WB
WBPERIM Perimeter length around WB
WBPNPTS Number of points around WB
WBPLAT1 -------------------------
WBPLON1 | |
WBPLAT2 | |
WBPLON2 | Latitude/Longitude |
. |coordinates of shoreline|
. | trace around |
. | full perimeter of WB |
WBPLATn | |
WBPLONn --------------------------
NTSEG Number of Triangular Areal Segments
TSEG Repeating Group -----------------------------------
TSEGNO Triangular Areal Segment ID
TSEGLAT Latitude of centroid of TSEG
TSEGLON Longitude of centroid of TSG
TSEGLAT1 --------------------------
TSEGLON1 | Latitude/Longitude |
TSEGLAT2 | coordinate of |
TSEGLON2 | vertices of TSEG |
TSEGLAT3 | |
TSEGLON3 --------------------------
TEGDEPTH Mean Depth of TSEG
TSEGAREA Area of TSEG
TSEGTIDE1 Mean Lower Low Tidal Depth
TSEGTIDE2 Mean Lower High Tidal Depth
TSEGTIDE3 Mean Higher Low Tidal Depth
TSEGTIDE4 Mean Higher High Tidal Depth
TABLE E
HYDROLOGIC UNIT CHARACTERISTICS RECORD TYPE
(Data elements)
===========================================================================
Variable Columns Type1 Length Description
---------------------------------------------------------------------------
*CU 1-8 I 8 Cataloging Unit
DA2Q1 9-14 F 6 Drain Area for 2yr Peak=1 cfs
DA2Q10 14-19 F 6 Drain Area for 2yr Peak=10 cfs
DA2Q100 20-25 F 6 Drain Area for 2yr Peak=100 cfs
DA2Q1000 26-31 F 6 Drain Area for 2yr Peak=1000 cfs
LV2Q1 32-33 I 2 Level for 2yr Peak= 1 cfs
LV2Q10 34-35 I 2 Level for 2yr Peak= 10 cfs
LV2Q100 36-37 I 2 Level for 2yr Peak= 100 cfs
LV2Q1000 38-39 I 2 Level for 2yr Peak= 1000 cfs
*JANPAV 40-45 F 6 Precip Avg for Jan
*FEBPAV 46-51 F 6 Precip Avg for Feb
*MARPAV 52-57 F 6 Precip Avg for Mar
*APRPAV 58-63 F 6 Precip Avg for Apr
*MAYPAV 64-69 F 6 Precip Avg for May
*JUNPAV 70-75 F 6 Precip Avg for Jun
*JULPAV 76-81 F 6 Precip Avg for Jul
*AUGPAV 82-87 F 6 Precip Avg for Aug
*SEPPAV 88-93 F 6 Precip Avg for Sep
*OCTPAV 94-99 F 6 Precip Avg for Oct
*NOVPAV 100-105 F 6 Precip Avg for Nov
*DECPAV 106-111 F 6 Precip Avg for Dec
MORD1 112-115 I 4 Miles of order 1 streams
MORD2 116-119 I 4 Miles of order 2 streams
MORD3 120-123 I 4 Miles of order 3 streams
MORD4 124-127 I 4 Miles of order 4 streams
MORD5 128-131 I 4 Miles of order 5 streams
MORD6 132-135 I 4 Miles of order 6 streams
MORD7 136-139 I 4 Miles of order 7 streams
MORD8 140-143 I 4 Miles of order 8 streams
MITOT 144-149 F 6 Total miles of reaches
*DA 150-155 F 6 Drainage area (Sq.Mi.)
*PBAR 156-161 F 6 Mean annual Precip (in.)
*PANBAR 162-167 F 6 Mean annual Pan Evap (in.)
*HITMPF 168 B 1 Days 90 degrees and above
*GEO 169 B 1 Code for Quaternary,etc.
*RUNVAR 170 B 1 Runoff coefficient of variation
*RUNBAR 171-176 F 6 Mean annual runoff (in.)
*SNOBAR 177 B 1 Mean annual snowfall (in.)
*LAND 178 B 1 Code for land surface form
*TOPO 179 B 1 Code for mean elevation
*SOILS 180 B 1 Code for soils (Alphisols, etc.)
*FREEZE 181 B 1 Number of days air less than 32F
THE REACH FILE DIRECTORY
The Reach File Directory is a document which identifies all reaches
included in the Reach File. It consists of four items: Reach File maps,
alphabetic listings, numeric listings, and hydrologic listings. The
alphabetic, numeric, and hydrologic listings for a State contain entries
for every reach within USGS cataloging units which are within or border
that State. For a given State, a reach entered in one listing also occurs
in the other two listings, and can be found readily in the other two
listings from information in the first.
In the alphabetical listings, the reaches are arranged alphabetically
by the names of the streams and waterbodies. In the numerical listings,
the reaches are ordered numerically by cataloging unit and the three digit
segment number. The hydrologic listings can be used for finding the
reaches throughout the tributary system above and below a given reach
because the reaches are listed in hydrologic routing sequence.
Common Data Shown In the Listing
--------------------------------
All data items shown in the listings are contained in the Reach File.
The alphabetic, numeric, and hydrologic listings have several data items in
common. These shared data items are as follows:
Upstream LAT/LONG - The latitude-longitude coordinates, in decimal
degrees, of the upstream end of each reach.
SEQNO - A hydrologic sequence number which shows the relative order of
the immediate reach as it appears in the hydrologic listings.
This number is unique for a given generation of the Reach File,
but may change after new reaches are added or other improvements
are made in the file. Thus a date (September 1982) is shown as
part of the SEQNO column heading.
Length - The length of the immediate reach, in miles.
Type - Reach type for the immediate reach.
Reach Number - The 11-digit code which identifies a reach.
Reach Name - Name of the immediate reach. This item also contains in
parenthesis, the names of open waterbodies through which, or
into which, the listed streams flow. Pseudo-names, consisting of
an asterisk followed by a letter, are shown in the listings where
reach names are not yet in the file.
In addition to the shared data items, each listing contains information
unique to that listing.
Alphabetic Listings
-------------------
The alphabetical listings show reach names in alphabetical order and
are arranged by State. Each State listing identifies all Reach File
reaches within all cataloging units which are entirely or partially
contained in the State, or which border the State. Thus, for a given
State, the listings will include some reaches which actually fall in
neighboring States. These neighboring State reaches are included to
minimize the effort in interpreting the listings, especially where streams
cross back and forth across State border.
A description of each of the columns in the alphabetic listing, from left
to right, is as follows:
Upstream LAT/LONG - The latitude-longitude coordinates, in decimal
degrees, of the upstream end of each reach.
SEGNO - The hydrologic sequence number for the immediate reach
(described above).
Path Mile - The distance, in miles, from the downstream end of the
immediate reach to the terminus, as measured along the hydraulic
transport path. (A terminus is the downstream end point of a
drainage system where a stream enters an ocean, the ground, a
land-locked lake, one of the Great Lakes, or where it crosses
into another country.)
Length - The length of the immediate reach, given in miles.
Type - Reach type for the immediate reach (See Exhibit 2).
Reach No. - The eleven digit reach number for the immediate reach.
Chk Dig - The check digit for the immediate reach. This digit is
derived from the 11-digits of the reach number; it is intended to
be used for data quality control when entering new data in the
Reach File or any associated file.
Reach Name - The Name of the immediate reach. This column is sorted
alphabetically with all reaches of a given stream being listed in
upstream to downstream order. This column also contains, in
parenthesis, the names of open waterbodies through which, or
into which, the alphabetically listed streams flow.
Complement Reach Name - The name of a reach connected to the lower end
of the immediate reach. This reach and the immediate reach join
at their lower ends and flow into a downstream reach except in
some instances involving divergent junctions. Where a simple
junction occurs at the lower end of the immediate reach, there is
no complement.
Complement Reach No. - The eleven digit reach number of complement.
Complement BNK - The side of the immediate reach to which the
complement is connected. Left and right are indicated in this
column by "L" and "R" with an orientation looking downstream.
Numeric Listings
----------------
The numeric listings are organized such that all of the reaches within
a cataloging unit make up a distinct set of from 1 to 4 pages in the
directory. Within each cataloging unit, the reaches are ordered by the 3-
digit segment number. The top of the first page of a listing for a
cataloging unit contains the following data relating to the entire
cataloging unit:
CU - The 8-digit cataloging unit code.
AREA - The estimated area of the cataloging unit (square miles).
Total Reach Length - The sum of the lengths of all reaches in the
cataloging unit (miles).
STATES - The 2-character abbreviation for each State which
touches or contains the cataloging unit (FIPS abbreviation).
LAND FORM - Dominant land surface form class (USGS, 1970,
National Atlas, pp.62-63).
The entries for each reach in this listing contain the data elements
common to all listings plus the arbolate sum and the reach numbers for the
upstream and downstream connecting reaches. Because the first 8 digits of
the reach number are the same for each reach in a cataloging unit, only the
3-digit segment number is listed on each line in the body of this listing.
Column headings unique to the numeric listings are as follows:
Arbolate Sum - The sum of the lengths, in miles, of all digitized
reaches upstream from the base (downstream end) of the
immediate reach, including all branches of all streams above
it. This gives an indication of the size of the drainage
system upstream of the reach.
O.W. Reach - Open water reach. Entries in this column occur
where the immediate reach is a shoreline reach. This column
identifies open water reach which has been linked to the
shoreline reach so that the shoreline facilities may be
retrieved in hydrologic order along with facilities on the
hydraulic transport path.
Connecting Reaches:
UL - The upstream left reach.
UR - The upstream right reach.
DS - The downstream reach; the reach whose head is connected
to the lower end of the immediate reach.
COMP - The complement; the reach that flows into the same
junction as the immediate reach.
BNK - The side of the immediate reach to which the
complement is connected (looking downstream along the
immediate reach).
The 3-digit segment numbers of the connecting reaches are shown on the
right-hand side of the listing. In most cases, the connecting reaches are
within the same cataloging unit as the immediate reach. In these cases,
the actual 3-digit connecting segment number is given. If the connecting
reach is in an adjacent cataloging unit, a 3-letter code, such as 'AAA' is
given. At the end of the listing for each cataloging unit, a table labeled
"INTER-CU CONNECTIONS" gives the full 11-digit reach number corresponding
to each of the 3-letter codes shown in the listing.
Hydrologic Listings
-------------------
The hydrologic listings are organized in upstream to downstream order.
A distinctive feature of these listings is the branching pattern on the
right-hand side of the listing. For a given reach, the branching pattern
shows the 3-digit segment number, the stream level, and the upstream and
downstream connecting reaches. In reading the branching pattern, it is
helpful to consider the 3-digit number to be at the upstream end of the
reach.
It is important to note that the branching pattern does not indicate
whether a connecting reach is to the left or right of the immediate reach
and that the branching pattern is organized by stream levels. Stream
levels are determined relative to the terminal reach of the stream system.
A terminal stream system consist of a terminal reach and all reaches
draining thereto. For a given stream system, the terminal reach and the
mainstem reaches have the lowest level. Reaches tributary to a given reach
are one level higher than that reach. For instance, the Mississippi River
is a level-one stream and the Ohio River, which is a tributary to the
Mississippi, is a level-two stream. The level of a reach is indicated by
the column in which the reach is shown in the branching pattern, with the
higher level reaches to the right of the lower level reaches.
Most of the terminal streams in the Reach File have been designated as
level one, however, terminal levels greater than one have been assigned to
some systems as follows:
Level Description of Terminal Reach
1 Discharges into the ocean or the Gulf of Mexico
2 Discharges into the Great Lakes or the Great Salt
Lake
3 Discharges into Canada or Mexico
4 Isolated drainage, discharges into the ground
Another data item shown in the listings is the downstream sequence
number, labeled "DSNO" in the hydrologic listings. The entry for this
downstream reach can occur several pages down in the hydrologic listing.
The downstream sequence number is useful for quickly locating the entry for
the downstream reach.
Because the hydrologic listings are organized by State, there are
cases where connecting cataloging units in adjacent States are not included
in a particular State listing. Where this occurs, there will be a gap in
the hydrologic sequence of reaches for that State. These gaps are
indicated by four blank lines in the listing.
The Maps
--------
A Reach File directory map depicts transport reaches, reach numbers,
shoreline reaches, shoreline reach numbers, cataloging unit boundaries, and
eight-digit cataloging unit codes. The original maps, which are on 11" x
17" sheets, have a scale of 1:500,000. A map number is provided on the
bottom right corner of each map sheet. This number corresponds to the
latitude/longitude coordinates of the southeast corner of the geographic
area covered by the map. It is suggested that the maps be filed according
to these map numbers to facilitate access by latitude and longitude. Above
the thirtieth parallel, the maps each cover an area of one degree latitude
by two degrees longitude, except in some instances along the Atlantic and
Pacific Coasts. The remaining maps cover a one-degree by one-degree area.
Each directory map bears a name corresponding to one of the USGS maps in
the 1:250,000 scale series so that users may readily identify these more
detailed maps to find towns and other cartographic information not shown on
the Reach File Directory maps. The cataloging unit boundaries shown
on the directory maps correspond to those shown on the USGS State
Hydrologic Unit Maps and the Hydrologic Unit Map of the United States.
These USGS maps are valuable companions to the Reach File Directory Maps
and are available for sale through the USGS Map Distribution Centers.
Interpreting the Listings and Maps
----------------------------------
The name of a given stream or surface water feature is printed only
once in the alphabetized reach name column, except where a multi-reach
stream carries over to a new page, in which case its name is repeated in
the first line of the new page. Dots are used as ditto marks where a
stream of a given name includes more than one reach. Where different
streams have the same name, the name is repeated.
Many lakes and reservoirs are identified in the Reach File. Reaches
within lakes and reservoirs are shown in the listings as Type-A reaches
(see Table B for reach type definitions). Other open water artificial
reaches (Type-M) are included in the file to depict hydraulic transport
paths in some estuaries and wide rivers. The artificial reaches of all
lakes, reservoirs, estuaries, and wide rivers represented in the file may
be found in the alphabetical listings under the open water name, or under
the names of any Reach File streams which flow into or through the open
waters. Note that the numbers for artificial reaches are usually not shown
on the maps, but that shoreline reach numbers often are. It can be
difficult to distinguish between these numbers on the maps. Therefore, to
avoid confusing the two, the numbers of artificial reaches in any open
waters or wide rivers should always be determined from the listings.
When using an alphabetic, numeric or hydrologic listing for a
particular State, it is often necessary to refer to a Reach File Directory
map to determine the location of a reach within the State. The upstream
latitude/longitude coordinates are included in the listings to help
determine on which map a reach may be found. The maps are numbered
according to the latitude/longitude coordinates in their southeast corners.