diff --git a/R/readWQPdata.R b/R/readWQPdata.R
index f0f8ee887efcc463460f58fe82d03f162aaf69cf..750a59038233789636693171afc2660b280d7342 100644
--- a/R/readWQPdata.R
+++ b/R/readWQPdata.R
@@ -143,7 +143,7 @@ readWQPdata <- function(...){
       pCodeToName <- pCodeToName
       varExtras <- pCodeToName[pCodeToName$parm_cd %in% unique(variableInfo$parameterCd[!is.na(variableInfo$parameterCd)]),]
       names(varExtras)[names(varExtras) == "parm_cd"] <- "parameterCd"
-      variableInfo <- merge(variableInfo, varExtras, by="parameterCd")
+      variableInfo <- merge(variableInfo, varExtras, by="parameterCd", all = TRUE)
       variableInfo <- unique(variableInfo)
     }
     
diff --git a/R/readWQPqw.r b/R/readWQPqw.r
index ac1d2e29b4d4b4ce16381a989d54144a537e6865..195fcbe830087296c54e0edc8d9f918819db297f 100644
--- a/R/readWQPqw.r
+++ b/R/readWQPqw.r
@@ -152,7 +152,7 @@ readWQPqw <- function(siteNumbers,parameterCd,startDate="",endDate=""){
     varExtras <- pCodeToName[pCodeToName$parm_cd %in% 
                                unique(variableInfo$parameterCd[!is.na(variableInfo$parameterCd)]),]
     names(varExtras)[names(varExtras) == "parm_cd"] <- "parameterCd"
-    variableInfo <- merge(variableInfo, varExtras, by="parameterCd")
+    variableInfo <- merge(variableInfo, varExtras, by="parameterCd", all=TRUE)
   }
   
   attr(retval, "siteInfo") <- siteInfo