Video Example [Exit EPA]

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To view subbasins and subwatersheds within the stream network, perform the following:

1. Select your desired Navigation direction, Upstream or Downstream.
2. Click a point on the map. Subbasins and subwatersheds upstream or downstream of the selected location will be returned in the map. The Select Subwatershed tab in the tool pop-up shows statistics about the network of hydrologic units.

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Upstream navigation

When you choose to view Upstream hydrologic units, EnviroAtlas displays the following:

• The interactive map displays high-resolution subwatershed (HUC-12 level) hydrologic units upstream of the selected site are displayed. Grey results denote headwaters subwatersheds, green results denote other subwatersheds.
• The EnviroAtlas HUC12 Navigator tool displays a table with statistics about both the upstream and downstream networks of subwatersheds.

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Downstream navigation

When you choose the Downstream option, the map displays high-resolution subwatersheds (HUC-12) along the stream course downstream from your selected location to the outlet. The table in the HUC12 Navigator tool displays downstream network statistics.

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Aggregate Indicators

The Aggregate Indicators tab in the HUC12 Navigator tool allows for viewing summed or averaged EnviroAtlas metrics (indicators) for the upstream or downstream subwatershed network.

• After generating the desired upstream or downstream subwatershed network, click the Aggregate Indicators tab.
• Choose the indicator category from the Select Indicator Category dropdown menu.





• Choose the indicator from the Select Specific Indicator to Aggregate dropdown menu.





• Click the Recompute Aggregate button.

The EnviroAtlas HUC12 Navigator tool displays the sum or average of the indicator values for the entire displayed hydrologic network.