Iowa’s Native Milkweed Species

by Katelyn Rinicker | Sep 5, 2024

Milkweed is important! Not only do they provide beautiful flowers, but they are the host plant of Monarch Butterflies. Monarch caterpillars feed on the milky sap and leaves as they grow. Iowa has 18 native species of Milkweed, but I am going to cover the 4 most common. They are perennial plants and can grow in a wide variety of habitats. Milkweed make up the Asclepiadaceae family. This scientific name comes from the Greek God of healing and medicine; Asclepius.

IMG_6864.jpg-Common Milkweed Red Feather Prairie Polk Co by MK

Common milkweed (Asclepias syriaca) is probably what you think of when you hear the name milkweed. They have beautiful large blooms of pink flowers, typically from June until August. When under the right conditions, they can grow up to 6 feet tall! You can find common milkweed almost anywhere including fields, prairies, ditches, and disturbed areas.

Butterfly milkweed (Asclepias tuberosa) have vibrant orange flowers. These beautiful plants only grow up to 3 feet tall and stay tidy. They are a perfect option for your gardens! They bloom from June until August and their leaves are rough and narrow. They establish in dry open habitats like old fields and prairies. Unlike the rest of the milkweed on this list, butterfly milkweed does not have milky white sap.

MonarchOn SwampMIlkweedBuMKtedescoIMG_6020

Swamp milkweed (Asclepias incarnata) is one of the Monarch Butterfly’s favorite types of milkweed. You might also hear it referred to as rose milkweed. They have narrow leaves and bright pink flowers. Swamp milkweed blooms from July to August. They also smell just like bubblegum, so if you see one in the wild make sure to give it a sniff. Just make sure you don’t accidentally startle any stinging insects! These plants like to grow in wet soils on the edges of prairie potholes and marshes. They can grow to over 5 feet tall.

Whorled milkweed (Asclepias verticillata) spreads via seeds and rhizomes. Their leaves are thin and narrow and can look like needles. A monarch caterpillar can eat several plants. They can grow up to 3 feet tall, but most of the time they are much shorter. They bloom from July to September and have little white flowers. Whorled milkweed are one of the last blooming milkweed, which makes it a particularly important source of food for monarchs.

Milkweed have seed pods. You may have seen these pods cracked open in the fall or individual seeds floating gracefully in the air. If you plan on harvesting your own and planting them, the time to plant is now! Planting in the fall is exactly what milkweed needs to germinate. They require a cold period of weather followed by a warm period of weather; this is called cold stratification.

So now that you know all about milkweed, it is time to go grow some! Plant them everywhere! Plant them in your front yard, in your back yard, in all of your gardens, in your parent’s gardens. I love milkweed and so will you.

The Legacy of the IOWATER Program

by Dan Haug | Sep 3, 2024

For 18 years, staff with the Iowa Department of Natural Resources trained and equipped volunteers to test water quality in rivers and streams across the state, building a network of citizen scientists and conservation leaders in the process. The IOWATER program died in 2016 after a long battle with budget cuts, declining participation, and IT challenges. It is survived by the state’s largest river cleanup event (Iowa Project A.W.A.R.E.) and many volunteers who resumed or started monitoring with the support of the Izaak Walton League, county conservation departments, watershed coalitions, and local non-profits.

Laura Merrick tests nitrate in the green waters of Lake Darling

The first Iowa Water Summit in 2019 was a sort of a funeral for the IOWATER program and a passing of the torch to the Izaak Walton League’s Save Our Streams program. Several groups in Iowa are making good use of the Ikes’ online database, trainers and training materials, and extra supplies. However, stream monitoring in the post-IOWATER era is decentralized and locally-led. Prairie Rivers of Iowa thought we could all benefit from more collaboration, so we wrote a grant proposal that was funded by the Water Foundation. Over the past year, I’ve been meeting regularly with colleagues from the Iowa Environmental Council, Northeast Iowa RC&D, Pathfinders RC&D, Partners of Scott County Watersheds, Polk County Conservation, and Drake University to talk about water monitoring, lay the groundwork for some new tools, and help the Izaak Walton League plan a second Water Summit.

The second Iowa Water Summit (scheduled for Oct 8 in Des Moines) is an opportunity for anyone involved in a local monitoring program (or looking to start one) to come together and learn from the experience of others around the state. We’ll have time and space for displays and networking. We’ll have a panel about recruiting and retaining volunteers. We’ll have a talk about making sense of the data once you have it, and another about new methods like microbial source tracking. We’ll have a panel about communicating with the public and turning data into action. If you’re at all interested in water quality and water monitoring in Iowa, don’t be shy! Register before September 20!

A Project AWARE volunteer balances on a log jam to retrieve trash.

The other legacy of IOWATER is less trash in our rivers. Iowa Project A.W.A.R.E. was started in 2003 by IOWATER coordinator Brian Soenen, who now serves on the board of a non-profit that continues the tradition. This year, 269 volunteers in canoes removed and recycled 3.8 tons of trash from 60.2 miles of the Skunk River.

Denny Weiss handles a softshell turtle for a Project AWARE nature program.

This was my first year participating in the cleanup and I highly recommend it! In addition to the fun of being on the water and the satisfaction of leaving the river cleaner than you found it, I enjoyed good food, friendly people, and interesting evening nature programs, including live turtles and a dugout canoe!

A.W.A.R.E. stands for A Watershed Awareness River Experience, and I tried to raise some watershed awareness in my Monday afternoon talk about the hydrology and water quality of the Skunk River. For example:

The Skunk River starts near Blairsburg and joins the Mississippi River near Burlington after a journey of 274 miles. By that point, it drains more than 4000 square miles of central and southeastern Iowa.
Thunderstorms in the Ames area lead to a rise in water levels at Augusta eight days later.
Rain that falls in the watershed can reach streams quickly if it runs off the surface or travels through storm sewers or drainage tiles, but moves more slowly if it’s caught by ponds and wetlands or soaks into the ground. Some of the water entering Ada Hayden Lake in Ames showed chemical signatures of having been underground for more than 50 years!

Watershed characteristics can help explain water quality patterns in the Skunk River and its tributaries, as shown in this table. For example:

The North Skunk River watershed has steeper hills, so has higher turbidity levels. The South Skunk River watershed is flatter with more tile-drained cropland, so has higher nitrate.
The Skunk River receives effluent from 9 major wastewater treatment plants (Ames, Newton, Nevada, Mt. Pleasant, Grinnell, Fairfield, Oskaloosa, Washington and Montezuma) and 85 smaller systems, which contribute to higher phosphorus levels.

Cyanobacteria bloom in Lake Darling, July 2024

However, the most memorable and sobering lesson about watersheds was taught by Lake Darling. We camped three nights at the state park, and I had an opportunity to explore it on Monday when high water levels kept us off the river. Lake Darling State Park has a lot going for it: a large lake in a beautiful setting, with an active Friends group that has improved trails and facilities. But the water quality is appalling. During my visit, the beach had a warning sign posted due to high levels of microcystin (a toxin produced by blue-green algae). I have never seen water this green. It looked like a kale smoothie and smelled like manure.

What happened? In 2007, Iowa DNR was celebrating Lake Darling as a success story, after most farmers in the watershed participated in a program to control erosion and intercept runoff. A $12 million project to drain and restore the lake was completed in 2014. By every indication, these efforts were successful at reducing the amount of sediment entering the lake. However, other water quality metrics (orthophosphate, E. coli, and microcystin) have gotten worse. The most likely explanation is the manure from 30,000 hogs. Nine animal feeding operations have been built in this watershed since the park reopened. I calculated the density of livestock in Lake Darling’s watershed (598 animal units per square mile) and found that it’s highest of any lake in Iowa, and higher than all but a handful of rivers.

This is why it’s not enough to measure success by dollars of cost share spent or the number of practices installed. We need to be aware of both positive and negative influences on the water bodies that we care about, and we need to test whether water quality is actually improving. At the Iowa Water Summit, I’ll share some tools and tips for doing just that. Hope to see you there!

Say No to Neonics: What They Are and Why We Should Care

by Katelyn Rinicker | Aug 5, 2024

Neonicotinoid pesticides are detrimental to not only monarch health, but all pollinator health. If you have never heard of Neonicotinoids, or Neonics for short, and aren’t sure why you should care, I urge you to keep reading.

What are Neonicotinoids?

Neonics are a type of pesticide that attacks insects on a neurological level. This means “the way they work is by permanently binding to the nerve cells of insects, overstimulating and destroying them. Exposed insects often exhibit uncontrollable shaking and twitching followed by paralysis before eventually dying” (Lindwall, 2022). These pesticides are used in a variety of ways including on agricultural land, golf courses, lawns, gardens, and even in tick and flea repellents for our pets, making Neonics the most used pesticide in the USA since its development in the 1990s (Lindwall, 2022). I know how they affect insects and I’m not sure I’d want my little furballs anywhere near it.

Why should we care?

Neonics are applied to soil around a plant’s roots or, even worse, as a coating on a plant seed (Lindwall, 2022). If it is applied as a coating to a seed, the plant absorbs it as it grows. This means that the whole plant is now toxic to any insect that tries to have lunch (Lindwall, 2022). The sweet nectar, pollen, leaves, stems, and even fruit are not safe for insects to pollinate or munch on. “In large-scale studies in the UK, agricultural applications of seed-coated neonicotinoids were found to be associated with decreased abundances of bees and butterflies” (Van Deynze et al., 2024). Even when neonics are applied at nonlethal doses, they can weaken critical functions, such as an insect’s immune system, navigation, stamina, memory, and fertility (Lindwall, 2022). So if the chemical doesn’t outright kill the insect, it prevents it from reproducing and significantly decreases its quality of life.

Neonics are also extremely harmful to pollinators. They are non-selective, which means that all insects are affected by them. “Since their introduction, neonics have made U.S. agriculture nearly 50 times more harmful to insect life” (Lindwall, 2022). “Almost 45% of the 3374 articles on neonicotinoids published to date … addressed the issue of negative interactions of neonicotinoids with bees and other pollinators” (Jactel et al., 2019). There are so many articles on the internet that address neonics and call for a change in pesticide use. During a 17 year study on butterflies and neonics, it was found that the diversity of butterflies and abundance were negatively affected and declined (Van Deynze et al., 2024). It is thought that these pesticides may have triggered the decline of butterflies in 2003, when treated soybeans became available in the Midwest (Van Deynze et al., 2024). Butterflies aren’t the only pollinator affected by this nasty pesticide. Beekeepers have reported that more than 45% of their honeybee colonies have been lost between 2020 and 2021; this is the second highest colony collapse rate on record (Lindwall, 2022). That’s not all, Iowa is the home of over 4,000 native bee species including the already endangered Rusty Patched bumblebee. This means that all pollinators are at risk due to these chemicals.

This graph from Van Deynze et al. shows the correlations between pesticide use and the decline in monarch butterfly (D. plexippus) populations throughout the years.

So maybe you don’t care about some bugs. Well, it’s affecting people too. When applied to the soil around a plant, only about 2% – 5% actually get on the target plant, with the rest becoming residue on the soil outside of the plant’s root system’s reach. This residual pesticide then gets washed away by irrigation or rain into our waterways. These are areas we let our children swim and play in. These are areas we are fishing in. These are areas we live by and see daily. A 2015 study by the U.S. Geological Survey found neonic pollution in more than half of the streams it sampled nationwide (Lindwall, 2022).

EasternTigerSwallowtailPapilioGlaucus_FB

Don’t worry, we can still do something to help!

In 96% of cases, neonics can be replaced by alternative pest control and even better, in 78% of cases, at least one non-chemical alternative method can be used (Jactel et al., 2019). You can buy organic seeds to plant or check that the seeds you are using haven’t been coated in this liquid death for our insect friends. Planting more safe gardens with plenty of blooming plants is a great way to support pollinators. Growing milkweed is not only essential to monarch survival, but will attract bees and other insects as well. Even if you are in an apartment, you can help out! Growing some beautiful native plants like Hoary Vervain (Verbena stricta) or Butterfly Milkweed (Asclepias tuberosa) in a container garden on your balcony or patio are great options if you don’t have lawn space. Making sure that you have blooming plants in Spring, Summer, and Fall is essential to pollinators survival.

Citations

Jactel H, Verheggen F, Thiéry D, Escobar-Gutiérrez AJ, Gachet E, Desneux N,  (2019, August). Alternatives to neonicotinoids. Science Direct. https://www.sciencedirect.com/science/article/pii/S0160412019302351?via%3Dihub

Lindwall, C. (2022, May). Neonicotinoids 101: The effects on humans and bees. NRCD. https://www.nrdc.org/stories/neonicotinoids-101-effects-humans-and-bees

Van Deynze B, Swinton SM, Hennessy DA, Haddad NM, Ries L (2024, June) Insecticides, more than herbicides, land use, and climate, are associated with declines in butterfly species richness and abundance in the American Midwest. PLoS ONE 19(6): e0304319. https://doi.org/10.1371/journal.pone.0304319

Birds from Erv

by Dan Haug | Jul 11, 2024

photo montage of Erv Klaas and a whooping crane

Erwin “Erv” Klaas died on Saturday July 6. His passing is a great loss for Prairie Rivers of Iowa. He served on the board since its founding in 2001, started an endowment for the organization in honor of his wife Janet, and was a reliable presence at our events.

I received the news of his death on Sunday while visiting the International Crane Foundation with my family. We were watching a whooping crane, and my mother immediately recalled a birding trip that Erv had led to Nebraska’s Platte River many years back, perhaps as a contribution for our church’s silent auction. Among the awe-inspiring flocks of thousands of grey-feathered sandhill cranes, Erv had his binoculars trained on a single white-feathered whooping crane and was trying to help the rest of the group spot it. Mom said it was like a page out of “Where’s Waldo!” It’s a fun image to recall a one-of-kind ornithologist who loved sharing his passion for nature with other people.

Let’s think of Erv whenever we raise our binoculars! Here are five other birds (plus one plant and two insects) that remind me of his life and legacy.

Horned lark. Photo by Kenneth Cole Schneider.

Horned Lark (Eremophila alpestris)

Shortly after I was hired, Erv took me for a driving tour of the Ioway Creek watershed. As an assistant commissioner for the Story County Soil & Water Conservation District (and a representative for the group on the Watershed Management Authority), he was well-aware of how some farming practices could degrade soil, water, and wildlife habitat, while other farming practices could preserve them. He pointed out examples of both on our drive. At one point, he told me to pull over so he could take out his binoculars and get a better look at a flock of non-descript birds hopping and fluttering about on the open fields. Up close, they’re adorable! Horned larks are gregarious birds that form large, mixed-species flocks, which could describe Erv too!

Drawing of a passenger pigeon hunt. (Public domain)

Passenger Pigeon (Ectopistes migratorius)

Erv believed that care for the land and its creatures is an ethical imperative. Toward that end, he organized a regular event where residents of Ames and the surrounding area would gather to read passages from Sand County Almanac and other essays by Aldo Leopold. One that I find especially moving is “On a Monument to the Pigeon,” first delivered in 1947, which includes poetic lines like this:

There will always be pigeons in books and in museums, but these are effigies and images, dead to all hardships and to all delights. Book-pigeons cannot dive out of a cloud to make the deer run for cover, or clap their wings in thunderous applause of mast-laden woods. Book-pigeons cannot breakfast on new-mown wheat in Minnesota, and dine on blueberries in Canada. They know no urge of seasons; they feel no kiss of sun, no lash of wind and weather. They live forever by not living at all.

Trumpeter swan, spotted on Ioway Creek watershed tour with Erv (2017-09-15)

Trumpeter swan (Cygnus buccinator)

The trumpeter swan could have gone the way of the passenger pigeon (there were only 69 birds remaining in the continental US in the 1930s) but the population has made an impressive recovery (63,000 by 2015). Erv is part of that conservation success story: in 1971 he joined the US Fish and Wildlife Service and conducted research on the effects of DDT on birds that helped lead to a national ban in 1973. It’s been a great joy to see large flocks of trumpeter swans on the lake at Ada Hayden Heritage Park, another of Erv’s signature projects. They also like CREP wetlands constructed to improve water quality; that’s where we spotted this one!

Vallisneria americana - by Fredlyfish4 via Wikimedia commons

Tape grass (Vallisneria americana)

This aquatic plant is an important food source for waterfowl and nursery for fish. It has an amazing pollination strategy, with boat-like male flowers and corkscrew-stemmed female flowers! Anne Kimber (my stepmother) studied this plant for her PhD and remembers Erv’s kindness when she ran into difficulties with the field work. I have similar memories. After some setbacks with a data analysis project, I received a phone call from Erv offering encouragement. He told me that I was a scientist in practice if not in credentials, that my work was important, and encouraged me to seek out collaborators and look for ways to bring it to completion. I took his advice.

Eastern pondhawk dragonfly, by Erv Klaas

Eastern Pondhawk (Erythemis simplicicollis)

This is one of many photos that Erv took of adult dragonflies and damselflies at Ada Hayden Heritage Park, continuing his dedication to science in retirement as a volunteer. The aquatic juveniles showed up in his nets when he surveyed benthic macroinvertebrates for the IOWATER program. He monitored water quality monthly at two sites on Ioway Creek from 2002 to 2015, at one point finding unusual bacteria results that were traced back to a cracked sanitary sewer. The IOWATER program is ended, but Prairie Rivers of Iowa continues to support volunteer water monitoring in Story County and is building tools and relationships to help groups across the state learn more from the data they are collecting.

Greater yellowlegs, by VJAnderson (CC-By SA).

Greater Yellowlegs (Tringa melanoleuca)

I saw one of these unmistakable shorebirds while paddling on the Skunk River below Ames. It was on its spring migration from the Gulf Coast to the Hudson Bay. They are pretty common now, but could be in trouble as the planet warms. Erv was deeply concerned about the impact of climate change on wildlife, water and people here in Iowa and around the world, and founded the Ames Climate Action Team to nudge the City government toward more aggressive action. It’s a great example of “think globally, act locally.”

A monarch obstacle course, with osprey overhead

Osprey (Pandion haliaetus) & Monarch Butterfly (Danaus plexippus)

While families were tagging monarch butterflies and doing hands-on educational activities at Ada Hayden Heritage Park, I spotted this osprey soaring overhead. The “Monarch Magic” event in 2023 exemplifies what Prairie Rivers of Iowa does best: initiating conversations and building partnerships to do things together that no one organization would have attempted on their own, and educating the public to deepen our connections to the places where we live. Our new pollinator specialist (Katelyn Rinicker) is already working on planning the next one. It’s one way Erv’s legacy lives on, even among people who never met him.

How Big is the Elephant in the Room?

by Dan Haug | May 15, 2024

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.

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.

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.

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.

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.

South Skunk River Cleanup – Spring 2024

by Dan Haug | Apr 24, 2024

16 people participated in the cleanup (2 not pictured, photo credit: Jake Moore)

On April 20, volunteers cleaned up trash along a 3.5 mile stretch of the South Skunk River in Ames, from River Valley Park to S. 16th St. Several people also ventured up Ioway Creek, and those who stayed on shore had plenty to do. The fast current meant we arrived at the destination earlier than expected, where we set to work clearing out an abandoned campsite. Judging by some of the items we found, families with children had stayed there, so please support organizations that work on affordable housing and provide emergency assistance. In between stops at sandbars to retrieve trash, there was ample opportunity to enjoy the river. The fast current made for a fun ride through some mini-rapids (nobody tipped!), and we saw kingfishers, great blue heron, and a bald eagle.

Volunteers launched canoes at N. River Valley Park in Ames (credit: Liz Calhoun)

Chilly weather (high of 48 degrees) may have dampened some of the initial enthusiasm for our spring 2024 creek cleanup event. We went from having not enough canoes for everyone who registered, to several extra canoes. With a smaller flotilla than last spring, we can’t claim a record breaking haul, but we did remove more more trash per person! In addition to the usual cans, bottles, plastic and styrofoam, finds included four tires, seven empty propane tanks, a shopping cart and a microwave.

April 2023: 3,020 pounds/40 people = 76 pounds/person
April 2024: 2,100 pounds/16 people = 131 pounds/person

Tony Geerts likely exceeded that average figure, arriving at the take out point with a big tractor tire. It would have made a great picture, but as I was rushing up to capture the moment, my phone slipped out of my hands and into the river! Fortunately, other people took photos and have shared them with me.

Volunteers with 2500 trash removed from South Skunk River

Assembling the tools, canoes, food, and people was a collaborative effort involving Prairie Rivers of Iowa, the City of Ames, Story County Conservation, the Skunk River Paddlers, and the Outdoor Alliance of Story County. Thank you to all who volunteered, organized, and supported the event.

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