If you a using a Spread report for your NPDES all you need to do is set the font to the barcode font:

1.  You need to determine the type of font the state requires (i.e. code 39, interleved 2 of 5, etc...).  Once you know the type, you need to get the barcode font for windows.  If the state cannot provide the font, simply search on the web for the font (i.e. "Code 39 barcode font").  You should be able to find a free or low cost font on the web.

2.  Download and install the font.

3.  Open your report in spread design.  Click on the cell where the barcode should  be displayed (you may need to merge cells to get the barcode to fit).  Type in the value for the barcode (state should tell you what they want).  Set the font to the barcode font you installed.  Barcode should be displayed. 

If you are using the canned NPDES report (Report Pac, NPDES), you cannot display a barcode.  Therefore you MUST use Spread Design to output your NPDES report.