It’s Rude to Point, but…

It’s Rude to Point, but…

By my calculations, over 65% percent of the nitrogen load in Ioway Creek on May 20 came from less than 1 percent of the land area in the watershed.  We still don’t know why.

Revised May 31

Many people assume that fertilizer applied to turf grass is a major source of nitrogen and phosphorus pollution in Iowa.  At a presentation to the Ames City Council, I was asked if a public awareness campaign aimed at lawn care professionals and homeowners would be an effective way to improve water quality in Ioway Creek.  If we’re talking nitrogen, I don’t think so:

  1. Because turfgrass covers a tiny proportion of the land in most Iowa watersheds, compared to cropland.
  2. Because turfgrass is a perennial. Having something growing and taking up available nutrients year-round is the principle on which cover crops reduce nitrogen loss.
  3. Because there was a study by Dr. Keith Schilling that found very low nutrient levels in shallow groundwater below six Iowa golf courses.
Turf grass in the rain

To that list, I can add local water quality monitoring including lab testing and sensor results from May.  Nitrate in Ioway Creek and the South Skunk River were the highest we’ve seen for a few years, but while rural tributaries ranged from 12-20 mg/L of nitrate, College Creek (an urban watershed with plenty of turf grass) measured only 2.3 mg/L.

But even if turf grass in general isn’t a serious water quality problem, maybe some specific areas of turf grass are a problem.  That’s what I thought after reviewing the data from our spring water quality snapshot on May 17.  Volunteers found a big difference in nitrate levels between South Duff Ave and other sites in Ames.  I wondered if it could be a mistake, so I went back out on May 20 with a bottle of test strips and a smartphone app that enables more precise measurements.  It wasn’t a mistake (nitrate in Ioway Creek increased from 8.6 mg/L to 24 mg/L in two miles), but the results still weren’t making sense, so I kept testing and testing until I assembled the map below.  By my calculations, 65% of the nitrate load in Ioway Creek that day was coming from just 1,500 acres!

map showing nitrate results on May 20

The 1,500 acres includes Coldwater Golf Links, and the pattern looks like what I’d expect to see if the golf course was overapplying fertilizer.  However, the golf course superintendent has informed me that fertilizer has not been applied since fall, and then only at a low rate.  A volunteer tested two ponds on the course and found low levels of nitrate (1-2 mg/L).

The 1,500 acres include some developed areas north of creek drained by storm sewers, but I tested water trickling from two outfalls on May 20 and found very low nitrate levels: 0.5 mg/L and 3.1 mg/L.

Worrell Creek at golf course

The 1,500 acres acres also includes two construction sites: a flood mitigation project near South Duff Ave and an ISU recreation complex east of Jack Trice Stadium.  The photo shows severe bank erosion where drainage from the ISU construction site enters the creek.  An inspector with the Iowa DNR noted problems with erosion control earlier this spring on the South Duff project.  However, if the nitrate spike were linked to erosion, I’d expect to see high phosphorus and low transparency.

Honestly, I’m not sure what’s going on here.  It’s not a pattern we’ve seen in previous years.

erosion on Ioway Creek between Grand and Duff avenues

When interpreting this kind of data, there is a risk of jumping to conclusions and unfairly pointing fingers.  In my first draft of this article, I suggested that Coldwater Golf Course was the source of the nitrate and the bank erosion.  That was premature.

However, there is also a risk that we will waste time and money on the wrong solutions or the wrong areas if we don’t test water or don’t follow where the data is pointing.  It’s clear from this month’s data and many other rounds of testing that water quality impacts are not uniformly distributed across the landscape.

Our October 2021 volunteer monitoring event is a little different

Our October 2021 volunteer monitoring event is a little different

Thanks to the 15 volunteers who helped to catch benthic macroinvertebrates (bugs) and test water quality over the weekend!

Volunteers capture benthic macroinvertebrates with a kick net, one of two methods we tried.

Ioway Creek “Snapshots” in May and October are a tradition going back to 2006.  Volunteers test water quality at many locations on the same day to get a better picture of what’s going on in the watershed. Since the IOWATER program ended, Prairie Rivers of Iowa has gathered supplies and planned events to keep the tradition going, but this year there was just one little snag: there was barely any water in Ioway Creek or its tributaries!

For most of this fall, our usual gathering place at Brookside Park has looked more like the photo on the left.

Not a problem.  The South Skunk River still had flowing water, and this was as good an opportunity as any to survey benthic macroinvertebrates (aquatic bugs), an indicator of water quality and habitat quality in rivers.  We were helped in this task by Susan Heathcote, a trainer with the Izaak Walton League’s Save Our Streams program.  If you’d like to become certified and missed out on this opportunity to complete the field portion of your training, keep an eye out for more training events with Susan in early spring.

Photo credit: Rick Dietz. Volunteers pick invertebrates off rocks and leaves and sort them in ice cube trays.

In addition to crawfish and dragonflies (always a hit with kids), we found a variety of smaller critters, including sensitive mayflies and stoneflies.  Overall, the invertebrate community in the South Skunk River was “good.”  In contrast, another stream we surveyed this week (West Indian Creek south of Nevada) had a “poor” score with mostly net-spinning caddisflies.  We’ll discuss some possible reasons for this difference at a webinar on November 2nd.

Another option for when streams are dry is to spend some time interpreting the data we have.  Following some water quality testing in the Skunk River, I gave a presentation to put those measurements into context.  I think the data feels more relevant when you’re at the water’s edge and have just gone through the process of collecting it! If you prefer to do your learning somewhere warm and comfortable, we’ll be covering similar information at a webinar on November 2nd.

This fall, nitrate is zero in most streams that have any water, but over the past 15 years we’ve been able to see which tributaries have the highest and lowest levels.

Another hitch.  Thunderstorms were forecast for Sunday!  We changed the date to Saturday and are glad we did; the weather was beautiful.  This also gave us the opportunity to set up equipment so we could capture water samples from the big rain on Sunday. Three volunteers helped me retrieve a dozen samples on Monday.  The samples will be tested for E. coli bacteria and optical brighteners, which may help us find and fix septic and sewer leaks.

Ryan checks a crest stage recorder (a low tech tool for seeing how high the water got) and puts a fresh bottle in a storm sampler.

Many thanks to all who participated. We hope to see you at the next watershed snapshot in May, and hope the water levels will be back to normal!

2021 Spring Water Quality Snapshot

2021 Spring Water Quality Snapshot

Excuse the delay in posting the data. I had shared this with the participating volunteers but not with a broader audience. I was distracted by the dramatic change in water quality a week later. However, the results from the spring snapshot event is more typical of what we’ve been seeing this year–clear and drying up!

On the weekend of May 15, fifteen volunteers tested 25 sites on Ioway Creek and its tributaries.

Volunteers practice testing phosphate and dissolved oxygen.

Like most of 2021 so far, water levels were way below normal, and light rains Saturday afternoon did little to change things. A few volunteers tested their sites Sunday, but water levels had dropped back down by the time.

Water levels (blue) in Ioway Creek are below normal (triangles).

With streams running low and tiles not flowing at all, most sites were as clear as we can measure (transparency greater than 60 cm), had low nitrate (2 mg/L or less) and low phosphate (0.1 or less).

But there were a few interesting exceptions.

Nitrate concentrations were a little higher (5 mg/L) in the middle reaches of Ioway Creek, starting at Hwy E18 in Boone County and continuing to Moore Park in Ames. The upstream reaches in Hamilton County and the downstream reaches in Ames had low nitrate levels.

“Gilbert Creek” had higher nitrate (5 mg/L) and much higher phosphate (1 mg/L) than other sites. When streams are running low, effluent from wastewater treatment plants can make up a significant portion of streamflow and can have a big influence on water quality. When streams are running high, effluent becomes a small fraction of streamflow compared to runoff from cropland. Wastewater plants in Iowa are only beginning to install technology to improve nitrogen and phosphorus removal.

The upper reaches of Ioway Creek in Hamilton County. Good water quality on May 15, but warm, not much shade.

Some urban streams showed elevated chloride levels (125 mg/L), but still within Iowa standards for aquatic life (389 mg/L thresholds for chronic exposure). Road salt dissolves and makes its way into groundwater, so we can see it’s influence in spring and summer, but testing before and after winter storms can give us a clearer picture.

The little creek below Ames High School (SC23) had muddy water (transparency of 32 cm) and dissolved oxygen low enough to harm aquatic life. We know that when it does rain this creek gets a lot of stormwater runoff (the video we produced with City of Ames shows this in action) and construction could also be an influence.

I don’t have a good explanation for lower dissolved oxygen and transparency at other locations.

Filling a transparency tube in Montgomery Creek, one of the murkier sites this year.

Thanks to our volunteers for spending a morning testing water! Our next event will be in October.

Weather Whiplash Returns!

Weather Whiplash Returns!

“If it never rained, we’d have great water quality in Iowa.”

-Jim Richardson

“If it never rained, we’d have great water quality in Iowa,” joked a volunteer at our May 15 water quality snapshot. 15 of us spent the morning testing Ioway Creek and its tributaries in Boone, Hamilton, and Story County and were marveling at the low nitrate levels and crystal clear water at the majority of our sites.

I wish more creeks in central Iowa were like this spot in Boone County. Cows fenced out the creek, a CREP wetland upstream keeping nitrate levels low, orioles and a kingfisher flitting between the trees.

Well, we’ve had some much-needed rain in the week since, and water quality has gone from good to bad. I’ve written before about “weather whiplash” that explains some of the big swings in nitrate over the past decade and here’s an early hint of it. Here’s data from a nitrate sensor in Ioway Creek installed by IIHR-Hydroscience and Engineering. A five-fold increase in nitrate concentrations in just one week! The water has gone back down but the nitrate levels are still above the drinking water standard.

Graph showing a big increase in flow and nitrate levels after a rain storm

And here’s some water samples I collected on Friday May 21. No, that’s not my coffee thermos, that’s some of the world’s best top soil washing down the Skunk River!

Four samples collected May 21, after a 3/4 inch rain

That’s not to blame the weather. It does rain in Iowa and if your farming practices let a plume of topsoil, manure, or fertilizer wash off the field every time that happens, you’re doing it wrong! Some farmers are doing it right (I saw some cover crops this spring near Nevada and lots driving on I-80) but not enough, especially in the Ioway and South Skunk River watersheds.

Water quality monitoring has been top of mind for Prairie Rivers of Iowa lately and I see an challenge and an opportunity. It’s a challenge to interpret data and track our progress when one good rain can cause water quality to go from clear to coffee-colored overnight! There’s an opportunity to be more strategic about how and where we test, so we notice and communicate more eye-opening moments like this one, and hopefully persuade a few more people to protect soil and water.

Update: June has been abnormally dry and Hamilton, Boone and Story County are experience severe drought. Droughts stress is impacting crops and smaller streams are drying up.

What’s carried with snowmelt?

What’s carried with snowmelt?

When snow melts, salt applied to melt snow on sidewalks, roads, and parking lots can make its way to streams. Freshwater critters don’t like living in saltwater. Are we getting to a point where they’d have trouble? Not quite, the chronic levels of concern for Iowa is 389 mg/L of chloride, and this sample (from a creek near Ames High School) and some others in our area were just shy of that last weekend. But be mindful of how much salt you’re scattering if we get some more icy days this month–people often apply more than what’s needed for safety!

The Izaak Walton League’s Winter Salt Watch is a good way for people to check on water quality during the winter and learn more about the issue.

What else is being carried in snowmelt? Our lab tests from late February are showing higher nitrate and bacteria levels than January’s tests. Check back in mid-March and we’ll get that data organized.