---
title: Mapping your watershed
description: "# Mapping your watershed To begin mapping your watershed, first collect all of the materials you will need.  A pencil and a topographical map are very helpful.  Topographical maps display physical features of the land such as hills, valleys, ridges…"
url: "https://aml-connect.org/aml-knowledge-base/mapping-your-watershed-2/"
updated: "2026-01-12"
category: Watershed Tools and Methods / Watershed 101
---

# Mapping your watershed

# Mapping your watershed

To begin mapping your watershed, first collect all of the materials you will need.  A pencil and a topographical map are very helpful.  Topographical maps display physical features of the land such as hills, valleys, ridges and channels.  A map can be obtained through your local USGS (US Geological Survey), a map store, or from your local conservancy.  The lines on a "topo" map represent the altitude of that area.  Closely spaced lines indicate rapid changes or steep slopes while widely spaced lines represent gradual changes.

1) Use a topographic map to locate the river, lake, stream, wetland, or other waterbodies of interest.

![](https://i0.wp.com/amrclearinghouse.org/Sub/WATERSHEDbasics/step1.jpg)

2) Trace the watercourse from its source to its mouth, including the tributaries.  This step determines the general beginning and ending boundaries.

![](https://i0.wp.com/amrclearinghouse.org/Sub/WATERSHEDbasics/step2.jpg)

3) The lines on the map are known as contour lines.  Contour lines connect all points of equal elevation above or below a known reference elevation.  The numbers beside the lines indicate  the elevation.  Thin lines mark 10 foot intervals in elevation, while thick lines mark 50 foot intervals in elevatioon.

![](https://i0.wp.com/amrclearinghouse.org/Sub/WATERSHEDbasics/step3a.jpg)

Contour lines that are spaced far apart indicate that the land is gently sloped and more level.  Closely spaced lines, however, indicate steep changes in elevation over a short distance.

![](https://i0.wp.com/amrclearinghouse.org/Sub/WATERSHEDbasics/step3b.jpg)

For the following steps go [here.](http://amrclearinghouse.org/Sub/WATERSHEDbasics/ZZMappingSteps.htm)