SOP-6.1.1.1
The Clean Water Team Guidance Compendium for Watershed Monitoring and Assessment
State Water Resources Control Board 6111.doc Page 1
Standard Operating Procedure 6.1.1.1
Reading Topographic Maps
Interpreting the colored lines, areas, and other symbols is the first step in
using topographic maps. Features are shown as points, lines, or areas,
depending on their size and extent. For example, individual houses may
be shown as small black squares. For larger buildings, the actual shapes
are mapped. In densely built-up areas, most individual buildings are
omitted and an area tint is shown. On some maps, post offices, churches,
city halls and other landmark buildings are shown within the tinted area.
The first features usually noticed on a topographic map are the area
features such as vegetation (green), water (blue), some information added
during update (purple), and densely built-up areas (gray or red).
Many features are shown by lines that may be straight, curved, solid,
dashed, dotted, or in any combination. The colors of the lines usually
indicate similar kinds or classes of information: brown for topographic
contours; blue for lakes, streams, irrigation ditches, etc.; red for land grids
and important roads; black for other roads and trails, railroads,
boundaries, etc.; and purple for features that have been updated using
aerial photography, but not field verified.
Various point symbols are used to depict features such as buildings,
campgrounds, springs, water tanks, mines, survey control points, and
wells.
Names of places and features also are shown in a color corresponding to
the type of feature. Many features are identified by labels, such as
"Substation" or "Golf Course."
Ground Configuration shown by contours
Topographic contours are shown in brown by lines of different widths.
Each contour is a line of equal elevation; therefore, contours never cross.
They show the general shape of the terrain. To help the user determine
elevations, index contours (usually every fourth or fifth contour) are wider.
The narrower intermediate and supplementary contours found between
