Styjun

I am trying to use ggplot to plot stream height gage locations from a dataframe (in Special Features or SF format) on top of Nebraska county shapefile data which was also read into R as a SF dataframe. The scale_fill_gradient piece of my code is not working and filling in the counties with a gradient.

I will show my code below to make it easier to understand:

#Read in Counties shapefile into an sf dataframe, filtering for just Nebraska counties
CountiesShapefile <- st_read('cb_2017_us_county_20m.shp')%>%filter(STATEFP == 31) 

#Read in Stream Gage Locations
NWIS <- read.csv('NWIS_SiteInfo_NE_RAW.csv')

#Convert the Stream Gage Dataframe to a SF Dataframe
NWISsf <- st_as_sf(NWIS,
 coords = c('dec_long_va', 'dec_lat_va'),
 crs = 4269)

#Read in Gage Flow Data
NWISFlow <- read.csv('NWIS_SiteFlowData_NE_RAW.csv')

#Using a Left Join to combine Stream Gage and Gage Flow Dataframes
NWISJoinClean <- left_join(NWIS, NWISFlow, by='station_nm')

#Convert Joined DF back to SF Dataframe
NWISJoinCleansf <- st_as_sf(NWISJoinClean,
 coords = c('dec_long_va','dec_lat_va'),
 crs = 4269)

#Use ggplot to plot the Gage Locations on top of the counties(this one worked)
GagePlot <- ggplot() + 
 geom_sf(data = CountiesShapefile, col='purple') +
 geom_sf(data = NWISJoinCleansf, col='blue')

#Use ggplot to plot gage sites on top of counties AND show the magnitude of gage 
#height by color, shape, or other visualization techniques(issue is here)
GagePlot2 <- ggplot() + 
 geom_sf(data=CountiesShapefile, col='black') +
 geom_sf(data=NWISJoinCleansf, aes(fill=gage_ht))+
 scale_fill_gradient("gage_ht",low='red', high='white')

"gage_ht" is a column in the NWISJoinCleansf dataframe, and it is a
number object. I got the same exact graph as I did for the code without
the scale_fill_gradient. My goal is to have the counties shaded by
gradient, with the darkest colors for the highest stream gage heights.
Does anyone know what I am doing wrong?

Edit:
I added the aesthetic to the second geom_sf line and it still didn't work.
Head of NWISJoinCleansf data frame