Earth Resources
Material Type:
Middle School
  • PEWI
  • pewi
    Creative Commons Attribution Non-Commercial No Derivatives
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    Lesson G. PEWI Manual 2022

    Lesson G. PEWI Manual 2022


    This collection is part of 5 separate overall collections funded through a National Oceanic and Atmospheric Administration (NOAA) Bay Watershed Education and Training (B-WET) grant. The five collections are: 1) VCU Chesapeake Bay Watersheds Mussels Field Studies: Middle School Lessons, 2) VCU Chesapeake Bay Watersheds Oyster Field Studies: Middle School Lessons, 3) VCU Chesapeake Bay Watersheds Mussels Role Play: Secondary Lessons, 4) VCU Chesapeake Bay Watersheds Oysters Role Play: Secondary Lessons, and herein, 5) VCU Chesapeake Bay Watersheds PEWI Mussel Simulation. 


    The PEWI simulation is located at this link:

    You will see the screen shown below and press play to begin. 

    Now you are in the PEWI simulation. Your screen should look like the picture below.

    You will see a large brown area that represents a watershed. The brown color represents the conventional corn land use, which is the default setting.

    The tool box, circled below and to the left of the screen, is how you will modify the land use. Notice as you change the land use by clicking the different icons in the land use tab of the tool box, the watershed changes as well. By selecting different tools in the tool box and placing them in the watershed, you change the nature of the watershed along with the results.

    Below you can see the conservation corn land use icon circled and directly to the right of the conventional corn land use icon. By clicking on the cells in the watershed, you will change the watershed to conservation corn. To change the entire watershed to a certain land use, hit shift and then click anywhere on the watershed.

    Use the grid paint icon circled below to individually paint land use types or put multiple land uses on the watershed at once.

    Shortcuts on your keyboard include:

    R - randomize land use types on the watershed.

    U - undo previous land changes

    D - rotate clockwise

    A - rotate counterclockwise

    W - pivot towards horizon

    S - pivot towards perpendicular

    Q - flying mode

    Up and down arrow keys - zoom in and out in flying mode

    Left and right arrow keys - to pan left and right in flying mode

    Right click - rotate watershed with mouse

    P - print

    Escape key - instruction options

    B - record actions


    Here are the other tabs in the tool box and what they do:



    When you press the glossary tab, you will find more detailed information on each of the icons, including definitions and video tutorials. 

    For example, in the Glossary, you will find very useful information on what Drainage Level and Soil Type is suitable for Alfalfa to grow. The Glossary Tool is very helpful in helping you make the best placement choices for your Land Uses.

    Physical Features and Soil Class Tabs

    For example you will be able to see on the map, all the different soil classes and their locations.

    Pop Up Bubbles

    As you place your mouse over different areas of the map you will notice that a box will pop up with a lot of useful information.

    Watershed Health Bars

    Be sure to look at the other Watershed Health Bars, as there are many factors that contribute to a successful Watershed.  In the Nitrate Concentration Bar, you can see data related to the service that mussels provide to the ecosystem by removing nitrate pollution. The mussel population must reach a sufficient level before it can provide this positive impact.

    Notice as the land use changes, so do the results. You can see the results to the right of the watershed, as shown in the picture below. In the picture below, the watershed is 100% grass hay, and the mussel population is now moderate.

    Units of measure for each parameter

    Where you see #  or  X   is where numbers will be inserted from the PEWI simulation tables.


    Mussel Population

    Stream Biodiversity


    Nitrogen and Mussel Services


    • None
    • Moderate
    • High


    # of mussels/ m2


    Note: 14 mussels per square meter is the largest value.



    X/100= higher values mean greater biodiversity


    X pts/year



    x/100= higher values mean that there is greater pollution control for that land use for the pollutant nitrogen- high numbers are good


    Nitrogen levels:

    X ppm/yr

    X mg/L/yr


    Mussel Services:

    X ppm/mg/L= small values appear when the mussel population is high enough to have a modest impact on the nitrogen levels

    Current: X/100:
    This is a measure of how well your land use is preventing sediment from entering the PEWI river


    Sediment loads:

    X tons/yr


    X Mg/yr



    Results Tab

    You can also click on the results tab located on the far right of the screen, shown below.

    This results tab provides you with the information about the impact of what you have selected and applied in the PEWI Tool Box. Notice that when you click results, another screen will pop up: graphics and tables. Both display the same information but in a different format. Graphics will display your results in visual formats, while tables will show the results numerically.

    The graphics are a brief overview of the results and include 3 sections which are shown below. The tables explain the results with more detail than the graphics.

    ** Keep in mind that individual results will vary, as underlying factors such as precipitation and temperatures are randomized for each session. **

    For more help, you can access the home page through this url

    Iowa State University has a “Teachers Guide” and you can find their lesson plans and youtube tutorials on playing the game when you click “Learn PEWI”.

    The Learn PEWI section provides resources and tutorials for the different ways to learn PEWI, as well as the basics. The Lesson Plans section will provide you with the resources for you to teach PEWI and the key concepts. There are several types of lesson plans to choose from.