<http://water.usgs.gov/nawqa-only/gw.html>
This data set consists of counts of underground, leaking underground, above ground, and total storage tanks for 500-meter and 1000-meter buffers around NAWQA sampling sites. The storage tank location infomation is from the 1998 StarView database published by Vista Infomrmation Solutions, Inc. The sampling sites are from the NAWQA data warehouse, April 2005. All sampling sites are included.
This is one of the ancillary GIS data layers developed to characterize NAWQA sampling sites for national synthesis of water-quality data.
Stations in Alaska and Hawaii are included. Some sites that fall outside the US boundary (ie a few in REDN and quite a few in PUGT) will have zero counts.
<http://water.usgs.gov/nawqa-only/gw.html>
The core processing method was to create a tabulation listing all storage tanks near each NAWQA sampling site. The ArcInfo command that does this point-to-point tabulation is POINTDISTANCE which has a limit of 130,000 points.
So, the first step was to first select the 6771 NAWQA non-SW sites and do a reselect with overlap against the 1.3M tank points coverage. The resulting two coverages both had fewer than 130,000 points so the POINTDISTANCE command could be run.
Each starview point has its source coded as follows: 2=underground storage tank (UST) 3=leaking underground storage tank (LUST) 17=county database LUST 21= aboveground storage tank (AST) 22=county database UST
These were recoded so all would be tabulated UST, LST, or AST.
The POINTDISTANCE output was then reselected for all pairs with the DISTANCE item int he table <= 500 and <= 1000 to tabulate using these two buffer distances. The FREQUENCY and GROUP2ROW commands were then used to count up the number of UST, LUST and AST records around each NAWQA sampling site.
The final file structure includes STAID and counts for the two buffer distances of UST,LUST,AST and the total of all. There may be double-counts in there, as one site may be in both StarView's LUST and UST databases, for example.
The data set is organized by STAID (station id).
The fields are:
STAID USGS Station id T5UST USTs within 500 meters of site T5LUST LUSTs within 500 meters of site T5AST ASTs within 500 meters of site T5PTS all tanks within 500 meters of site T10UST USTs within 1000 meters of site T10LUST LUSTs within 1000 meters of site T10AST ASTs within 1000 meters of site T10PTS all tanks within 1000 meters of site
cprice@usgs.gov
cprice@usgs.gov