Answer Key


Identify a medium resolution NHD feature


1. Why does this feature have a Null name and GNIS ID?


Answer: This feature is not a named feature therefore both its GNIS name and ID are Null.


2.  The FCode for this feature is 39009. What does this mean?


Answer: The FCode 39009 attributes this LakePond as Perennial with the Stage, or height of water surface, at average water elevation. You can find this information in the NHD Feature Catalog.


3. The Reach Code of this feature is 10190003002230. In which Subbasin can this feature be found?


Answer: This feature can be found in Subbasin 10190030. The first 8 digits of a Reach Code are the Subbasin the reach is located in, while the last 6 digits of a reach code uniquely identifies the reach of the feature. 



Identify a high resolution NHD feature


1. The Fcode of Cherry Creek is 46006. What does this mean?


Answer: Cherry creek is attributed as a perennial Stream.


2. The flow direction of Cherry Creek is attributed as "With Digitized". What does this mean?


Answer: The flow direction of Cherry Creek is known. When flow direction is "Uninitialized" the flow direction is unknown. This is very common with CanalDitches in areas that do not have a lot of change in elevation such as in Florida. If you zoom to 1:36,000 or larger, flow direction becomes visible.



Identify a watershed boundary


1. Which Hydrologic Region contains Denver?


Answer: Denver is contained in region 1019. The first four digits of the Subbasin provide the HUC for the Hydrologic Region in which the Subbasin is found.


2. What is a HUC?


Answer: The Hydrologic Unit Code, or HUC, is a code given to a Watershed that indicates the level of the Watershed.