Downloading Data From the NHD Viewer
Download a Dynamic Extract
If you do not need to download an entire prestaged Subregion for your requirements, you can order data dynamically. The NHD Viewer can be used to locate and download a dynamic extract. However, dynamic extracts will require some processing time before delivery and are typically available within a couple of hours. In this tutorial we will use the NHD Viewer to locate a specific hydrographic feature called Dillon Reservoir. We will then zoom to the Subbasin in which Dillon Reservoir resides. This Subbasin is called the Blue River Subbasin, and has an eight-digit Hydrologic Unit Code (HUC) of 14010002. Finally, we will use the Data Download Tool to download the Subbasin.
This Tutorial is also available as a movie demo!
Download a Dynamic Extract
Step 1 Open the NHD Viewer
Go to the NHD Homepage.
The navigation panel on the left hand side has a tab called "Get NHD Data". Hover your mouse over the tab and then select the option, "Go to the NHD Viewer".
The viewer will open in a new window.
What is the NHD Viewer?
Step 2 Locate Dillon Reservoir
Start by using the search box at the top of the screen to search for Dillon, Colorado where Dillon Reservoir is located.
The results for the search will be identified in the Selection Panel on the Left side of the Viewer.
Choose "Zoom to" underneath Dillon, CO. Dillon should be the first option on the list.
The Viewer will zoom to the city of Dillon, Colorado.
Step 3 Zoom to Subbasin 14010002
What is a Hydrologic Unit Code?
Zoom to Subbasin 14010002 (displayed as HUC8-14010002 in the viewer) by scrolling your mouse wheel until the entire Subbasin is visible. Notice as you zoom out fewer hydrography features are visible.
Zoom out to a scale where all hydrography layers are turned off and you are viewing only watershed boundaries.
Step 4 Set the Reference Area in the Download Data Tool
Start by clicking on the Download Data button in the top right of the screen.
In Download options, choose NHD Subbasins as the reference polygon. Make sure the options menu appears as it is shown below.
Subbasin Boundaries are now highlighted.
Step 5 Select and Download Subbasin 14010002
14010002 is now highlighted in green and the Selection tab on the left side of the screen provides options such as "Download", "Zoom To", and "More".
Select "Download" to view a window for "USGS Available Data".
In addition to Hydrography, you can also download other data themes for this Subbasin. Check the box next to Hydrography.
In the drop down menu next to Hydrography, you will see options to download the Subbasin as a file geodatabase, a personal geodatabase, or as a shapefile. Choose File Geodatabase, and then click "Next". File geodatabases are preferred for NHD downloads because they typically have smaller file sizes than a personal geodatabase.
Not sure what the difference is?
The next window provides an option to download the National Hydrography Dataset with or without a flow table for the Subbasin.
What is a flow table?
Click the first option for National Hydrography Dataset (without a flow table). Then click "Next".
The selected products are added to your Cart.
The Cart appears on the left side of the screen and shows Subbasin 14010002 as a selected item.
You can add an additional item to your cart by selecting another Subbasin. For example, select the adjacent Subbasin called 14010003. Click on "Download" and under "USGS Available Data", choose the Hydrography theme with File Geodatabase format. Click "Next", and select the National Hydrography Dataset without a flow table. Finally, select "Next" to add to Cart.
Step 6 Check out
Click Checkout in the Cart. You will be prompted to enter your e-mail address.
Enter your e-mail address and click "Place Order." You will receive an e-mail confirmation shortly verifying that your order has been received.
After a few hours you will receive another e-mail with a link to download your Subbasins.
Download the zip files and copy them to a local directory.
Extract the Subbasins from the zip file to a folder. Right click the zip file and choose "Extract to folder". File geodatabases contain many files and it helps to keep them organized by extracting to a folder.
You are now ready to use the NHD Data in ArcMap!