diff --git a/R/readNWISdv.r b/R/readNWISdv.r
index ff0684bbaa2553e032dcda981495e4c388f2a5f5..3f91c327e49b6ee51d1286b36e483116f156ac5e 100644
--- a/R/readNWISdv.r
+++ b/R/readNWISdv.r
@@ -66,6 +66,7 @@ readNWISdv <- function (siteNumber,parameterCd,startDate="",endDate="",statCd="0
   data <- importWaterML1(url, asDateTime=FALSE)
   if(nrow(data)>0){
     data$dateTime <- as.Date(data$dateTime)
+    data$tz_cd <- NULL
   }