Story County stream monitoring, 2024
Daniel Haug, Prairie Rivers of Iowa
2025-01-14
Introduction
Prairie Rivers of Iowa and its partners completed our fifth year of a water monitoring project in Story County. Updated through December.
Bear Creek was mostly open water when we tested in December.
# 2024-03-28 Started over with 2024 data
# Import csv file provided by City of Ames
# Skip unneeded columns for tidy format
library(tidyverse)
library(readr)
library(lubridate)
ameslab2024 <- read_csv("data/ameslab2024.csv", na = "NULL",
col_types = cols(CollectionDate = col_date(format = "%m/%d/%Y"),
CollectionTime = col_skip(), Comment = col_skip(),
MRL = col_skip(), LabID = col_integer(),
Method = col_skip(), Note = col_skip(),
Symbol = col_skip(), Unit = col_skip()))
# renames a column for clarity
ameslab2024 <- rename(ameslab2024, site = Description)
View(ameslab2024)
# Tidy the data, so each analyte is in a column
ames_tidy<- ameslab2024 %>%
pivot_wider( names_from = Analyte, values_from = Result) %>%
mutate(Year = year(CollectionDate), Month = month(CollectionDate, label = TRUE),
Day = day(CollectionDate))
# Adds a column from a lookup table to allow ordering sites from upstream to downstream
library(readr)
lookup_US_DS <- read_csv("data/lookup_US_DS.csv")
ames_tidy <- left_join(ames_tidy, lookup_US_DS, by = "site")If you see a car stopped by a bridge in Story County with someone pulling up a milk jug of water on a rope, there’s a good chance it’s me or volunteer Rick Dietz, doing our monthly monitoring route. We collect water samples from 10 sites, and City of Ames staff cover another five. Laboratory Services for City of Ames Water and Pollution Control tests the samples for nitrate, total phosphorus, total suspended solids, and E. coli bacteria.
Weather and flow conditions
Story County was in drought
when streams were sampled in October, March, February, and January.
Spring was a little wetter than normal. This graph shows flow rates in
the South Skunk River below Ames. 
December 18. Ioway Creek and its tributaries could not be sampled due to ice.
November 20. Two days after rain. Creeks were flowing again at all sites. No bacteria sample from Ballard Creek–cracked sample bottle.
October 16. Drought conditions. Ioway Creek and its tributaries, Keigley Branch, and Ballard Creek had stopped flowing and some reaches were dry.
September 18. Abnormally dry conditions. Ioway Creek and its tributaries and Ballard Creek had stopped flowing and some reaches were dry.
August 21. Light rain (0.14 inches) the day before. Stream flow in the South Skunk River dropped below 100 cfs, which is normal for this time of year. Worrell Creek and College Creek were not sampled.
July 17. Light rain two days before. Water levels slightly above normal. Missing sample from College Creek.
June 19. Rain the previous night (1.46 inches at the Ames Airport). Rivers were high and muddy.
May 15. After heavy rains the previous week (Ioway Creek and the South Skunk River did not flood, but came close), water levels were coming down but still were above normal.
April 17. It had rained the previous day and water levels were normal to high at all sites.
March 20. Despite light rain the previous week, water levels in the South Skunk were well below average for this time of year. Unseasonably warm weather had continued, contributing to algae growth in many streams.
February 28. Sampling was delayed one week due to lab workload and staffing. We sampled on a very cold morning, but the previous week included several days with high temperatures in the 60s and 70s, so most sites still had open water. The sample from E. Indian Creek sample was spilled and some urban streams could not be sampled because of low water levels.
January 17. Most sites could not be sampled due to thick ice.
E. coli bacteria
The support of a certified lab provides a backstop for volunteer monitoring and allows us to make direct comparisons with laboratory data from DNR and other agencies. It also allows us to test for E. coli bacteria, an indicator of fecal contamination from human waste, livestock, pets, or wildlife.
