With the dry winter continuing, an increase in the use of well water for irrigation seems inevitable in the upcoming season. Since well water typically contains more salts than surface waters, it may be worthwhile to review thresholds for salinity effects on productivity across various crops. There are a couple UC ANR publications that do so concisely here:

http://anrcatalog.ucdavis.edu/pdf/8066.pdf

and

http://vric.ucdavis.edu/pdf/Irrigation/EvaluatingSalinityinIrrigationWater.pdf

Also, this CE publication from Colorado State presents a nice summary as well as a table for how to convert between the various units that salinity is reported in:

http://www.ext.colostate.edu/pubs/crops/00506.html

If you have questions about the information here or want to discuss irrigation salinity topics with me, feel free to give me a call or email me.