README_bmp.TXT - Readme file

WHAT IS AN RDB FILE?

An RDB file is an ASCII file that has been exported from a relational database 
(RDB) and maintains the tabular structure so it can be imported to any common 
spreadsheet or database program.  The data are provided in tab-delimited columns 
with the first row being the Column Header Names and the second row indicating 
the field length and data type of each ('S' for a character field; 'D' for a 
date field; 'N' for a number field; for example '12S' indicates a character field
of length 12). The data are preceded by lines of documentation or explanatory 
text. Any row containing such comments starts with a '#' sign. 

Since the RDB files are text-based, they are easily viewable in a web browser or
any word-processing program like MS Word or Notepad. However, those programs will
not format the data into correctly-aligned columns, because the files are 
tab-delimited (the columns do not have fixed widths). These tables are provided 
with the intention that they will be easily imported into a spreadsheet or 
database program (such as Quattro Pro, SAS, Access, and Paradox).


QUALITY ASSURANCE/QUALITY CONTROL SAMPLES

The water-quality data tables provided on this website show concentrations of 
environmental data (surface-water samples). In addition to the environmental samples, 
the Lake Champlain BMP study collected the following quality assurance/quality 
control (qa/qc) samples:

1. Source-solution, ambient, equipment, and field blanks for concentrations of total 
   phosphorus, total nitrogen, and suspended sediment. Up to 95 blanks were collected 
   depending on the constituents being tested during the period 1999-2007.
2. Field replicates (for samples collected both manually and using an automated sampler) 
   for concentrations of total phosphorus, total nitrogen, and suspended sediment. Up to 
   96 field replicates were collected during 1999-2007, depending on the constituents being 
   tested.
3. Split samples for concentrations of total phosphorus, total nitrogen, and suspended 
   sediment. Up to 102 split samples were collected during 1999-2007, depending on the 
   constituents being tested.
4. Cross-section representativeness samples that compare the point sample taken 
   using the automated sampler with a concurrent manual sample (using the grab or equal-
   width-integrated sampling method) for concentrations of total phosphorus, total nitrogen, 
   and suspended sediment. Up to 179 samples were collected depending on the constituents 
   being tested.

See Wilde and others (1999), for an explanation of types of qa/qc samples and sampling methods.

The qa/qc sample results are not available on the Web site; however, the following
is a brief summary of the qa/qc sample results:

	
	-Concentrations of certain nutrients were detected in some of the blank 
samples. However, these concentrations were usually at estimated concentrations 
below the Laboratory Reporting Limit and 2-10 times lower than the concentrations 
in the environmental samples.

	-All relative differences measured in concentrations between replicate and 
environmental samples were within the precision of the method for the specific 
analyte at a particular concentration range.

	-In some cases, results from cross-section representativeness concurrent
samples indicated that the automated sampler was not yielding representative
samples compared to an average value for the stream. These suspect samples were
flagged in the NWIS database such that they are not presented with a standard
retrieval and are not included with the data on this Web site.

	-Field parameters, dissolved oxygen, pH, turbidity, temperature, and 
specific conductance, were measured almost continuously until July 2002 and 
thereafter at most site visits. The continuous records were corrected and
finalized in the 2000 and 2001 annual water data reports (Coakley and others, 
2000, and 2001). For cases where an "E" is associated with a value, the records
for those days were rated fair or poor due to instrument malfunctions or lack of 
adequate qa/qc justification.


Anyone wishing to obtain the qa/qc data, please contact Laura Medalie of the 
New Hampshire/Vermont Water Science Center, Montpelier field office at 
lmedalie@usgs.gov.


REFERENCES

Coakley, M.F., Keirstead, Chandlee, Brown, R.O., and Kiah, R.G., 2000, Water
resources data New Hampshire and Vermont water year 2000: U.S. Geological
Survey Water-Data Report NH-VT-00-1, 192 p.

Coakley, M.F., Ward, S.L., Hilgendorf, G.S., and Kiah, R.G., 2001, Water
resources data New Hampshire and Vermont water year 2001: U.S. Geological
Survey Water-Data Report NH-VT-01-1, 194 p.

Wilde, F.D., Radtke, D.B., Gibs, Jacob, and Iwatsubo, R.T., eds., 1999, 
Collection of water samples: U.S. Geological Survey Techniques of Water-
Resources Investigations, book 9, chap. A4, accessed February 5, 2005, at 
http://pubs.water.usgs.gov/twri9A4/