You can now get the full dataset from readNWISpCode function, and it's up-to-date.

vignettes/dataRetrieval.Rnw

@@ -307,14 +307,6 @@ print(xtable(data.df,
 
 @
 
-% A complete list (as of November 7, 2014) is available as data attached to the package. It is accessed by the following:
-% 
-% <<tableParameterCodesDataRetrieval, echo=TRUE, eval=TRUE>>=
-% library(dataRetrieval)
-% parameterCdFile <-  parameterCdFile
-% names(parameterCdFile)
-% @
-
 Two output columns that may not be obvious are \enquote{srsname} and \enquote{casrn}. Srsname stands for \enquote{Substance Registry Services}. More information on the srs name can be found here:
 
 \url{http://ofmpub.epa.gov/sor_internet/registry/substreg/home/overview/home.do}