The Iowa Woodland Invasive Species Inventory Program is interested in knowing where certain invasive plants are found. Each invasive plant species may occur at any given density, from low to high. Also, the size of the woodland you are sampling may vary from small to large. No matter how dense a plant species is, or how large an area you are sampling, a precise location of the woodland and the invasive species is necessary. It is important that you know exactly where you found the different species you are looking for. For each woodland survey area you inventory, you will need to know exactly where that area is. This program is requesting that you use the Universal Transverse Mercator (UTM) system to locate your area(s).

UTM coordinates and how they are found

The UTM system is a way of pinpointing a location with a set of coordinates, and can be found using a 7.5' United States Geological Survey Quadrangle Map. Below is a description of how to use the UTM system. For additional help, use the slide show to learn about 7.5' USGS Maps and to help visualize the UTM technique.

1. UTM stands for Universal Transverse Mercator. It is one way to pinpoint a location on a map.

2. UTM is a grid system printed on all United States Geological Survey (USGS) 7.5 minute topographic maps. The grid is divided into Kilometers, and coincides with a series of numbers printed along the margins of the map.

3. The UTM numbers coincide with a light blue tick mark along the edges of the 7.5 minute map. Some 7.5' Quadrangles don't have the blue ticks, but instead have a fine black UTM grid laid out over the entire map, similar to the grid shown in the graphic.

4. What about UTM numbers? Why do they look funny? UTM numbers are numbers that are printed along the left, right, top, and bottom of the 7.5' Quadrangle Map. The individual digits are printed in two different sizes, like this: 454 and 4661. This DOES NOT indicate where a comma or decimal goes. Apparently, the different sized digits help the reader distinguish the UTM numbers from the myriad of other numbers printed along the sides. Some of the other numbers represent Latitude and Longitude coordinates and Township and Range numbers, among others.

Each UTM number you see on the map is in Kilometers. These can be converted to meters by adding three zeros to then end of the numbers. Here's how:

Example 1: 454 kilometers is equal in distance to 454,000 meters.
Example 2: 4,661,000 meters is equal in distance to 4,661 kilometers.

5. The UTM system is laid out in a grid pattern. Think of finding a UTM coordinate like finding an (x) and (y) point in Algebra. In Algebra, it is called the Cartesian coordinate system.

6. There are two numbers to be found in a UTM coordinate. The first number coincides with an East direction (or "Easting"). This is (x). These numbers can be found along the top and bottom of the Quadrangle. The second number coincides with a North direction (or "Northing"). This is (y). These numbers can be found along the left and right sides of the Quadrangle.

7. Always "read RIGHT, UP" - find the distance to the EAST, then the distance to the NORTH.

8. 1 Kilometer = 1000 Meters. Each UTM grid square is 1-kilometer in length on each side, or 1000 meters on each side.

9. UTM coordinates can be found accurately to the nearest 25 meters using a
7.5' Quadrangle Map and an appropriate scale bar. For the purpose of the invasive species inventory, finding the UTM coordinates for your woodland to the nearest 100 meters is accurate enough.

10. Each set of UTM coordinates correspond to a given zone. Remember, most of Iowa is in Zone 15. Part of the state is in Zone 14, which includes parts of Lyon, Sioux, Plymouth, Woodbury, Monona, Harrison, and Pottawattamie Counties in western Iowa. See the United States Zone map.

11. To find out which Zone you are in, look in the lower left corner of a 7.5 minute topographic map.

12. An example of a UTM coordinate: UTM coordinates are written 454,250m E. x 4,661,500m N., Zone 15. (Read four hundred fifty-four thousand two-hundred fifty meters East by four million six-hundred sixty-one thousand five hundred meters North, Zone Fifteen). Remember to always include the Zone in your UTM reading. The UTM numbers are exclusive to just one spot in each zone, however, the same set of coordinates are used over again in every other zone.

13. This UTM coordinate will coincide with one woodland area. The coordinate should represent a point in the center of the area surveyed.

14. Why not use Latitude and Longitude or the Tier, Range, and Section (TRS - often called the Township, Section, and Range) to describe a location?

The advantage of using UTMs is that they are precise points independent of boundaries. They don't rely on legal descriptions or degrees. Tier, Range, and Section lines can cut a woodland area into several sections, which make it difficult to locate with just one description. For example, a given woodland may be cut in two by a section line, which requires you to describe each half of the woodland separately for each of the sections it falls into. So, if it fell into sections 7 and 8, you may have to describe the woodland like this: NE ¼ of the NE ¼ of Section 7 and W ½ of Section 8. Latitude and Longitude must be found using special scales, which take a lot of practice and time to use in order to find a Latitude and Longitude point. Some commercial gazetteers are available now that print Latitude and Longitude grid lines on the maps, which are very accurate and easy to read, but can cost quite a bit of money to buy. UTM coordinates are found on all 7.5 minute topographic maps, which can be purchased for around $6.00 at map stores or from the USGS, or can be viewed for free on the website, http://ortho.gis.iastate.edu.

15. Another advantage to using UTM coordinates is that they are increasingly becoming the convention in other monitoring programs. The UTM is also one of many coordinate systems included on hand-held GPS (Global Positioning Satellite) units.