How Big is the Elephant in the Room?

How Big is the Elephant in the Room?

elephant in the room

Iowa has a lot of hogs, poultry and cattle raised in concentrated animal feeding operations (CAFOs).  They produce a lot of manure.  However, CAFOs are not evenly distributed across the state, and it’s rarely practical to haul the manure long distances.  Do rivers with more CAFOs in the watershed have worse water quality?  I was curious and recently completed a big data analysis project to find out.  I’ve omitted some of the technical details in the interests of making this article easier to read, but hope to eventually submit this research to a scientific journal for peer review.  Get ready for a nuanced, data-driven look at the elephant in the room!

Livestock Density by Watershed

The water quality data for this study comes from 60 sites in Iowa DNR’s ambient stream monitoring network.  (Two sites were later dropped because of incomplete data).  For each monitoring site, I delineated a watershed (the land draining to that point) and overlaid databases of animal feeding operations.  CAFO density in these watersheds varies greatly: from 12 animal units per square mile in Cedar Creek near Bussey, to 883 animal units per square mile in the Floyd River near Sioux City.

Animal units are a way of standardizing herd size across ages and species.  For regulatory purposes, one 1000 pound steer is equivalent to 10 pigs under 55 pounds, 2.5 pigs over 55 pounds, 55 turkeys, or 82 layer hens.  Feedlots with at least 300 animal units are tracked in Iowa’s database.  Feedlots with 500 animal units require a manure management plan, and feedlots with 1000 animal units require a construction permit.  The Iowa Environmental Council continues to follow and raise concerns about these rules.

Map of CAFO density for 60 watersheds

Initial Findings and Complications

In the article that inspired this project, “The Fair, the Marginal, and the Ugly”, Chris Jones used this same dataset to rank water quality in Iowa’s rivers and noted that the river with the worst water quality has the most CAFOs.  The Floyd River had the highest nitrogen and total phosphorus, the third highest turbidity, and the sixth worst E. coli.  Sticking with the same time period (2016-2020) and similar metrics, I plotted water quality against livestock density for 58 sites to see if the Floyd River is part of a larger pattern.  For nitrate, yes; for total phosphorus, maybe; for turbidity and E. coli, no.  The relationship with turbidity is weakly negative; rivers with muddier water actually tend to have fewer CAFOs in the watershed.

Graph of CAFO density vs nitrate
Graph of turbidity vs CAFO density

The best explanation for this is that there is a third factor influencing both water quality and CAFO density: terrain.  CAFOs are most common in flatter parts of the state where construction permits are more likely to be approved and there is plenty of cropland nearby to spread the manure. The notable exception to the pattern is Bloody Run, a trout stream in northeastern Iowa.  In 2021, the Iowa DNR approved the construction of a 11,600 head cattle feedlot in this watershed, despite the steep terrain and abundant sinkholes.  Given the timing, I am excluding this site from analysis and hope we do not have to find out what happens to water quality when this much manure is added to an environmentally sensitive area.

Slope and cropland are also correlated with livestock density.

Primary drivers of water quality

To better understand the interactions of multiple variables without a lot of statistics, I like to color-code one of them (in this case, CAFO density) and then focus on a narrow range (in this case, watersheds with less than 160 animal units/square mile).  You’ll see this technique several times in this article.  This shows how slope and cropland in the watershed influence water quality, independent of CAFOs.

Slope: As you’d expect, turbidity in rivers is strongly correlated with the average slope of land in the watershed.  Steep hills are more susceptible to runoff and erosion.  Phosphorus and E. coli are also attached to sediment and carried by runoff, so are moderately correlated with turbidity, and weakly correlated with slope.

Cropland: Nitrate in rivers is strongly correlated with corn and soybean acres in the watershed.  Long-term nitrate trends can also be explained by changes in cropping patterns (a replacement of hay and small grains with corn and soybeans).  I’ve heard corn and soybeans described as a leaky system, and want to echo that.  Whether the nitrogen comes from manure, ammonia, or soil organic matter, if you don’t have something green and growing in the early spring, you’re going to lose a lot of it. 

Graph of turbidity vs slope for watersheds with few CAFOs
Nitrate vs cropland in watershed, for watersheds with few CAFOs

 Manure and Bacteria in the Water

E. coli is a bacteria found in the guts of birds and mammals, an easy-to-measure proxy for poop in the water and the pathogens that might come with it.  For many environmentalists, the reason for Iowa’s long list of impaired waters seems frustratingly obvious. Hogs, poultry, and cattle outnumber humans, dogs, geese, raccoons, and deer, so they must be the main source of E. coli.  Here’s an example of that kind of thinking from a report by the Environmental Integrity Project.

“Iowa is America’s hog capital – and also one of the most unhealthy areas in America to swim in rivers and streams. That’s in part because of the vast amounts of hog waste and farm runoff polluting the state’s waterways.”

The same logic showed up in the watershed management plan for Ioway Creek (and some others like it), which assessed likely bacteria sources based on the population of various kinds of animals and the amount of manure they excrete per day.  While the consultants were careful not to say that hog confinements in Hamilton County were the main reason for chronically high E. coli in the creek, I sure got that impression from reading the maps and tables.   

Looking at livestock populations turns out to be an unreliable way to guess which rivers will have bacterial impairments.  Statewide, there is no correlation between E. coli in the river and livestock density in the watershed.  The three worst rivers for E. coli  in this dataset (the Soldier River near Pisgah, Maquoketa River near Maquoketa, and W. Nodaway River near Shambaugh) have less than 320 animal units per square mile, on the low side for Iowa.

E. coli vs livestock density

More sophisticated models take into account the fraction of manure that reaches streams, how long it takes to get there, and how much of the bacteria dies off in the meantime.  Unsewered communities, geese on the beach, raccoons in the storm sewer, and cows wading in the creek produce much less manure than animals in CAFOs, but a larger fraction of the manure is delivered directly to the water when it’s still fresh.  That’s not to say that manure from CAFOs have no influence on E. coli in rivers.  Once rivers with slopes steeper than 4% were excluded, the remaining sites had a moderate correlation between E. coli and livestock density. 

E. coli vs livestock density for sites with less than 4% slope

Manure Nutrients in the Water

If manure is applied to fields that are not too steep and set back from streams, during appropriate weather conditions, and especially if the manure is knifed into the soil, very little of the solids, E. coli bacteria and pathogens in the manure should reach streams.  The same is not true of the nutrients in the manure.  Nutrients cycle between different forms, and the more readily dissolved forms (nitrate and orthophosphate) can easily leak out of the root zone during periods when crops aren’t growing, and make their way to streams.

Watersheds with a high density of CAFOs tend to have much higher nitrate concentrations, but most of that is because those watersheds also have a large proportion of the land in row crops.  However, focusing on sites with at least 80% of the watershed in row crop production, there is still a positive correlation between livestock density and both nitrate and total phosphorus.

Total phosphorus vs livestock density

In the science assessment for the Iowa Nutrient Reduction Strategy, manure was not treated as a challenge for nutrient reduction, it was treated as a best management practice.  It makes a certain amount of sense: manure is a slow-release fertilizer that adds organic matter to the soil.  Compared to plots fertilized with commercial fertilizer, plots fertilized with swine manure had 4% less nitrate loss by 46% less phosphorus loss, mainly due to soil improvements that reduced the amount of runoff.  However, those agronomic trials must have used a different set of application rates than usually occurs in practice.  If you look at both commercial fertilizer sales and manure availability, counties with many CAFOs apply nitrogen and phosphorus at higher rates, with consequences for water quality.  Here’s one study from Minnesota and another from Iowa that document this.

Closing thoughts

Prairie Rivers of Iowa has worked with some large swine and cattle producers who were early adopters of cover crops and who are very careful about how they manage manure.  We salute their efforts to improve soil health and protect water quality.  A study like this can only address the impacts of the industry as a whole.

Swine manure leaked into a creek in Greene County in summer of 2023.

This project was funded in part by a research grant from the Raccoon River Watershed Association, which has been monitoring water quality in Greene County.  Last summer, the group watched with alarm as hog manure leaking from an earthen storage basin turned the water in a creek brown and caused the dissolved oxygen in the water to drop to zero.  These kinds of incidents happen way too often, but usually affect a small stretch of stream for a short period of time, so don’t show up in monthly water quality datasets.

The correlations between water quality and livestock density disappeared entirely when I looked at two drought years (2021-2022).  During dry periods, runoff and tile drainage from farmland is minimal, but effluent from sewage treatment plants and industry (including meatpacking plants) can have a bigger influence on water quality.  Manure from CAFOs definitely impacts water quality in Iowa, but if we’re too quick to blame them in every situation, we may miss what’s really going on.

Water quality results for 2023 in Story County

Water quality results for 2023 in Story County

Our 2023 Annual Report is now available with results of both volunteer and lab testing of water quality in lakes and streams in Story County.  The 56-page report can be navigating by clicking on headings in the table of contents or by using the “Bookmarks” feature in your PDF reader.  Below are some of the key findings.

Amelia Whitener leads a water monitoring demonstration at a trash cleanup event.

The volunteer program continues to grow and improve in consistency.

  • 49 volunteers entered 969 data sheets into the Clean Water Hub this season.
  • Many volunteers are monitoring their assigned site biweekly, with 20 sites sampled at least 20 times.
Mayfly larvae (nymph) under magnifying glass

This was a challenging year for fish and aquatic insects.

  • In addition to many creeks drying up, volunteers observed dissolved oxygen drop to low levels at 53% of stream sites. 
  • Biological surveys showed mixed results, with some streams scoring poorly but sensitive insects like mayflies present in others.
Cows with access to creeks are one possible source of E. coli bacteria

E. coli bacteria levels in streams remained high.

  • All thirteen streams with enough data to evaluate this season exceeded the primary contact recreation standard. Three streams exceeded the secondary contact recreation standard: (West Indian Creek, College Creek, and Ballard Creek.
  • However, over the last four years, most sites on the South Skunk River meet the standard when there is enough water to float a canoe.
UV disinfection system at Ames Water Pollution Control Facility

Wastewater treatment plants are not yet capable of removing some of the pollutants we monitor, and can have a large influence during drought when effluent is less diluted.

  • Effluent from the old sewage treatment plant in Nevada was found to be a major source of E. coli bacteria. The new plant, currently under construction, includes a disinfection system that should address the problem.
  • Stream sites downstream of sewage treatment plants tend to have elevated chloride and phosphate.  
Stock photo of cover crops

The encouraging trends we noted in the 2022 report held up with another year of data. Water quality trends are often driven by weather, but we pulled out subsets based on streamflow to remove some of this influence. 

  • E. coli in the South Skunk River below the Ames Water Pollution Control Facility has improved relative to the pre-2014 baseline period, especially during dry conditions when wastewater has the greatest influence.
  • Nitrate in the South Skunk River below the confluence with Ioway Creek improved relative to the pre-2014 baseline period, even after excluding dry periods. This pattern is consistent with improvement from conservation practices.
Prairie Rivers of Iowa Has Had a Busy and Productive 2023

Prairie Rivers of Iowa Has Had a Busy and Productive 2023

Hello and Happy 2023,

Prairie Rivers of Iowa has had a busy and productive 2023 in Iowa, working on a variety of important initiatives related to creating a healthier natural environment and preserving the rich cultural heritage of Iowa.   As we end this year, we have touched kids, families, landowners, historic homeowners and business owners, communities, natural resource professionals, like-minded not-for-profits and oversaw a national prairie conference in Iowa.

Here’s a summary of some of the key accomplishments and initiatives this year:

EDUCATIONAL VIDEO SERIES – We created a weekly video series for YouTube and Instagram The Clean Water Act: 50 Years, 50 Facts. We produced 45 short videos filmed at dozens of locations (including knee deep in a marsh) and featuring 5 music parodies.  The educational videos covered various aspects of water conservation, law and policy.

Water Testing Ioway Creek Near Stratford in Hamitlon County

MONTHLY STREAM MONITORINGConducted monthly monitoring of at least 15 streams, providing updates in the Prairie Rivers monthly newsletter.  Additionally, coordinated volunteer “snapshots” with neighboring counties and supported school groups interested in water monitoring. Additionally, we published a 65-page report analyzing water quality data, including a novel way of looking at the data.

SECURED A NATIONAL FOUNDATION GRANT – This grant assists us in building a network for interpreting water quality monitoring data.  Seven partners joined Prairie Rivers to focus at sharing best practices, looking for tools to monitor E. coli in our streams, providing a monthly opportunity to express their concerns and planning for an Iowa Water Summit in 2024.

Ioway Creek Cleanup

TWO TRASH CLEANUPS — (1) May 2023 — Cleaned Ioway Creek by canoe, S. Grand to S. 16th St (Ames), 40 participants.  The trash collected weighed 3,020 pounds and included 20 tires and three rims. Partners included: Story County Conservation, Skunk River Paddlers, the City of Ames, Outdoor Alliance of Story County.  (2) August 14, 2023 – Cleaned a tributary of Ioway Creek in Stuart Smith Park (Ames), on foot, nine volunteers, 350 pounds of trash removed.  Partners included Iowa Rivers Revival, Green Iowa AmeriCorps and the City of Ames.

POLLINATOR CONSERVATION Launched a 10-year plan involving over 40 persons serving on a committee to support pollinator conservation.  This plan is aimed at conserving pollinators and their habitats, which are crucial for the environment.  You can see the plan at

Monarch Magic Family Fun Event on September 9th, 2023

MONARCH MAGIC Held the first Monarch tagging event in September, where over 300 kids, their families, and others learned about pollinators and tagged 146 Monarchs.  We had 10 sponsors and partners at Ada Hayden Heritage Park and plan to do it again in 2024.

HISTORIC RESOURCE PRESERVATIONReceived a grant from Iowa Cultural Affairs and successfully surveyed 319 historic listings on the Lincoln Highway National Heritage Byway.  In 2024, we will present the findings to elected officials and other interested persons in the 43 communities along the Byway to inform and develop a plan for the restoration and preservation of these important Iowa heritage properties.

BYWAY COORDINATOR AND PROJECTS – Hired a new Byway Coordinator, Jeanie Hau, who is actively working to support our Byway projects.  Prairie Rivers signed a new contract with the Iowa DOT to support work on the Iowa Valley Scenic Byway extending our efforts to preserve Iowa’s heritage.  This Byway begins on Highway 30, Montour turnoff, and travels through the Amana Colonies for a total of 77 miles.

TRAVELING EXHIBITThe Lincoln Highway National Heritage Byway traveling exhibit called The Promise Road:  How the Lincoln Highway Changed America has been displayed at various locations, allowing visitors to learn about the rich history of this historic road.  It’s available for display in museums, libraries, and other community spaces.  So far the exhibit has traveled to Jefferson, Grand Junction, State Center, Nevada, Linn County Historical Society: The History Center, Cedar Rapids History Museum, Nevada Library, Marion Public Library, Carroll Public Library, Harrison County Welcome Center, and currently at the Council Bluffs Public Library.

Lincoln Highway National Heritage Byway Traveling Exhibit

We cannot do this work without your support!

Today, we are asking you as a supporter to make an end-of-year gift of $50.00 to Prairie Rivers of Iowa.  Your support shows us to keep up the good work!   You can make a gift here online or by going to our donation page for additional options. We know that as good stewards of the land, you see how important this work is today.

It is so important for a not-for-profit to receive gifts from individuals. Hearing from you encourages and supports our very difficult work in support of the natural and cultural resources in Iowa.
Thank you!

Board of Directors
Reed Riskedahl, President
Mark Rasmussen, Treasurer
Doug Cooper, Secretary
Erv Klaas
Bob Ausberger
Chuck Stewart
Rick Dietz
Jim Richardson
Christopher Barber

Mike Kellner, Marketing and Public Relations
Dan Haug, Water Quality Specialist
Jessica Butters, Pollinator Conservation Specialist
Jeanie Hau, Lincoln Highway National Heritage Byway & Iowa Valley Scenic Byway Coordinator
Carman Rosburg, Office Manager
Daniel Huber, Technology
Shellie Orngard, Historic Properties Consultant

One-Time Donate to Prairie Rivers of Iowa
PRI Iowa Water Quality Specialist Awarded as a New Voice in Water Quality

PRI Iowa Water Quality Specialist Awarded as a New Voice in Water Quality

The Conservation Learning Group, a think tank based at Iowa State University Extension and Outreach has announced the 2022 winners of its New Voices in Water Quality Awards. Prairie Rivers of Iowa Water Quality Specialist Dan Haug is one of 15 Iowans being awarded. Haug was recognized for his excellence in youth and/or community water education.

In a recent Conservation Learning Group release, its director Jacqueline Comito said, “Each of these individuals was nominated by peers and recognized for their efforts, achievements and passion for improving and restoring water quality.”

The Outdoor Alliance of Story County (OASC) has worked with Prairie Rivers of Iowa, and particularly Haug, on a number of projects. In their nomination letter, the board cited Haug for his expertise at analysis and reporting, his role as an outstanding communicator and his leadership during water quality monitoring and creek cleanup events. “We recall a cold April morning when Dan trained volunteers on identifying macroinvertebrates from Ioway Creek. His enthusiasm was infectious, and the volunteers had fun collecting and examining the samples despite the very cold water,” the OASC further states in the letter.

Volunteers Searching for Macroinvertebrates

Volunteers searching for macroinvertebrates.

Water Quality Monitoring Instruction

Haug teaching water quality testing.

Iowa State University (retired) Teaching Assistant Professor of Agronomy Laura Merrick said of Haug, “Dan has been my closest collaborator starting in 2017 on a variety of citizen-science and community-based water quality monitoring and watershed-centered coalition-building initiatives. He has grown to serve in a central guidance role to transform the nature of community collaboration for monitoring and sustainable improvement of our regional water quality in surface rivers and streams and to promote youth and community water education.

Among Haug’s many accomplishments, starting in the spring of 2020 he was instrumental in assembling in Story County a 24-member planning team that developed a 10-year water monitoring plan with Haug as its primary author. He then subsequently authored its first annual report.

“As nice as it is to be recognized by the Conservation Learning Group as part of this dedicated group of water professionals, it was even more gratifying to know that nine friends and colleagues in seven different organizations sent nomination letters on my behalf.  It really speaks to the level of collaboration we have around water monitoring and watershed projects,” Haug modestly relates.

According to Prairie Rivers of Iowa Director Penny Brown Huber, “Trying to solve critical water quality problems takes dedicated people to understand what is happening. Dan is a key link to helping the public build their understanding so change can happen to improve water quality.”

To meet all the New Voices in Water Quality Award winners visit

Water quality Education at City of Ames Open House

Water quality demonstration at water plant open house.

Dan Haug During Ioway Creek Cleanup

Haug helping with Ioway Creek cleanup.

Watershed Education at Eco Fair

Watershed education at Ames Eco Fair.

Six Tips to Enjoy Iowa Lakes

Six Tips to Enjoy Iowa Lakes

lake at sunset

There is no better way to relieve stress and get an attitude adjustment than spending time by a lake, whether you’re fishing, swimming, paddling, watching wildlife, or watching the sunset.  But it’s hard to enjoy a lake if it’s choked with toxic blue-green algae. Cleaning up Iowa lakes so we can enjoy them will require some shifts to our attitudes.

1. Don’t Panic

I’m sure you’ve all heard about the “brain-eating amoeba” Naegleria fowleri. Iowa and Nebraska both had their first cases in 2022 (both fatal), contracted at the Lake of the Three Fires and the Elkhorn River, respectively. While scary, cases are also extremely rare. Nationwide there have only been 157 cases in the past 60 years, concentrated in the South. And even where the amoeba is known to be present, there are ways to enjoy the water while minimizing risk.

2. Check Where the Beaches are Cleanest

Iowa Environmental Council maintains a map and puts out a weekly report showing where there are beach advisories. The map also shows many lakes with no advisories (the blue umbrellas). For example, in Story County, the beach house at Hickory Grove Lake is sometimes closed due to high E. coli levels, but at Peterson Park, E. coli has been consistently below the detection limit. Not every lake in Iowa is hopelessly polluted, and even the most troubled lakes will have their good days.  Take advantage of them!

map of beach advisories
Peterson Park Lake
The beach at Peterson Park in Story County

3. Help clean up dirty lakes at the local level

Having spent some time enjoying a clean lake, hopefully, you are in a better frame of mind to tackle the not-so-clean lakes. There are lake improvement efforts all over the state that need the support of taxpayers or the help of landowners in the watershed. For example, Story County is planning a complete renovation of McFarland Park Lake, which recently suffered an algae bloom and fish kill.

“The renovation will: remove sediment, stabilize shoreline, increase lake depth, and improve lake habitat for aquatic plants and animals. Work will increase overall health of the lake, reduce the number of fish die offs in the future, and improve recreational opportunities.”

4. Keep clean lakes clean at the state and national level

It does no good to dredge out a lake if farmers in the watershed are going to plow up the hillsides around it. This is what happened to Lake of the Three Fires, as related by Chris Jones.  When a third of the county was converted from pasture to corn ground, the lake gradually returned to its former shade of brown. We can’t do much about naturally occurring amoebas, but we can take a hard look at the policies, business and purchasing decisions, and attitudes that shape farming practices across Iowa.

5. Think globally, act locally

The warmer the water, the more cases of Naegleria fowleri. The same goes for harmful algae blooms, a much more common problem in Iowa that is getting even more common. If we don’t reduce our greenhouse gas emissions fast, hotter temperatures and more intense spring rainstorms will continue to worsen our water quality woes. Fortunately, there are opportunities to reduce greenhouse gas emissions in Iowa while at the same time improving water quality in the short term by planting more deep-rooted perennials and cover crops, building up organic matter in the soil, and using less nitrogen fertilizer.

6. Share your favorite water memories

A friend was visiting from out-of-state when I wrote this article. A family vacation to Iowa of course included time with the grandparents and a visit to the Iowa State Fair, but he also set aside time to take his kids wading in Ioway Creek, where they caught minnows and marveled at the weirdness of dragonfly nymphs. For my friend, time spent outdoors in creeks and lakes was an essential part of growing up in Iowa, and he wanted his children to share that experience.

What a wonderful mindset to cultivate as we work to improve water quality!

The Community Academy explores Ioway Creek