Need fresh eyes to see what I'm missing

Before you create vel_by_month you can check vel for NAs and NaNs by

sum(is.na(vel))
sum(unlist(lapply(vel,is.nan)))

Eric,

There should not be any missing values in the data file. Regardless, I added
those lines to the script and it made no difference.

Running those commands on the R command line showed these results:

sum(is.na(vel))

[1] 2321

sum(unlist(lapply(vel,is.nan)))

[1] 0

Yet the monthly summaries retain the initial line:

vel_by_month

# A tibble: 67 ? 3
# Groups:   year [8]
     year month   flow
    <int> <int>  <dbl>
  1     0    NA NaN

I've another data set with the same issue (that's 2 out of 5) and I assume
the source of the problem is the same with both.

The data sets have no NAs or missing values at the end of a line.

Thanks for the ideas,

Rich