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Where is the NHD wetlands data?

Started by Boyd, July 18, 2015, 10:12:18 AM

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Have spent the past few days updating my NHD data to clean up old problems. Built a filemaker relational database that translates FCODE into MP_TYPE and GM_TYPE so all the objects are classified the way I want for Globalmapper and cgpsmapper.

But when I look at the results, there is almost no wetland data. In the past I've used the National Map to download NHD, but that is very confusing and tedious. Finally figured out that I could directly ftp everything here, which makes it much easier:

I have downloaded the highest resolution HU8 shapefiles directly and also the highest resolution files for the whole state. The wetland data  (Swamp/Marsh, FCODE = 46600) just isn't there. Here's an example of the current 2015 download. Water is blue, wetlands are green.

Compare that to the old 2010 data I have archived. No, all these wetlands have not dried up! ;)

Am I doing something wrong? It is not a question of how I am processing the data. The greens areas just aren't in the 2015 files. I believe the 2010 data was downloaded directly from the NHD before it was moved to the National Map.


Thinking about this some more.... maybe you need to order the dynamic extract version in order to get wetlands data? I remember this is how the old system worked, but hoped they were pre-packaging the data now.

Anyway, I ordered a dynamic extract of an 8 digit HU sub-basin and will compare this to the other downloads. They say it can take up to 2 days to get a response.  :(


The birds must have taken them along when the left after the winter. ;)

Checked my download from 8-13 and they were not there then either.  In other areas of region 2 there are some (also in the Everglades of region 3).  I would guess they are replacing the data with newer shoreline data.  This might take 5+ years before they rebuild the polygon data.  Ask about it on the NHD website; in the past they have been very responsive to my inquiries.


Thanks - glad to see there is still at least one other person here who makes maps, LOL  ;D

That is interesting, I was wondering if maybe it was just New Jersey. I checked the data I downloaded the other day, and there were less than 500 wetland areas in the entire state of New Jersey! There were 12,000 in the 2010 data.

So I decided to use the the NJ LU/LC wetlands data instead, it is actually very good. When I went to download the newest dataset, I found this on the NJDEP website, dated February 2015

QuoteThe water features from the LU/LC data sets, both the 2002 data and the 2007 data, were used to populate the New Jersey portion of the National Hydrography Database (NHD), which is a nation-wide database created by USGS to house all water features in the nation. NJDEP has taken over the stewardship of this important NHD data set, and is working to get the most detailed and accurate water feature data into the NHD system, and maintain all necessary NHD water codes.

Maybe there are some issues with the transition to the NJ data at NHD? Anyway, interesting to note that there are 325,000 wetlands features in the NJ 2012 LU/LC dataset! I believe this is because they have divided into much smaller areas and have a lot of different classifications for wetland areas.

Meanwhile, I am still waiting to get the final dynamic extract that I requested 3 days ago. The smaller areas (8 digit HU codes) were available two days after I ordered. I requested one large 4 digit area and still haven't received the download link. But I don't have much hope that it will be different from the pre-staged data. The smaller dyanamic extracts look the same as the other data I downloaded.

Now this whole experience makes me wonder what else might be missing from the current NHD data. I noticed other differences from 2010 in the foreshore areas along the coast but have not looked to see if they reflect an actual change yet.


I have not made a map since 2011.

The 2013 data has about 20 small 46600 polygons in the nw along the PA & NY borders and a 5 x 6 mile area along the se coast about a 1/3 of the way up (Great Egg Harbor ?).

That will we a sizable map with 325,000 wetland polygons.