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. 

Many people assume that fertilizer applied to turf grass is a major source of nitrogen pollution in Iowa.  I didn’t:

  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 the distinguished Keith Schilling that found very low nutrient levels in shallow groundwater below six Iowa golf courses.
Worrell Creek at golf course

But I’m open to new evidence.  Last week, volunteers testing water quality in Ioway Creek found a big difference in nitrate levels between South Duff Ave and other sites in Ames.  I thought it might 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 pollution treasure map below.  Aha!  The treasure must be buried at Coldwater Golf Course!

map showing nitrate results

This does not seem to be a general problem with lawn fertilizer in Ames that can be solved with an education campaign aimed at home owners and lawn care companies.  College Creek has plenty of turf grass in its watershed and measured only 2 mg/L nitrate as nitrogen.  I also tested storm sewers on the north side of the creek: 0.5 mg/L and 3.2 mg/L.

Honestly, I’m not sure what’s going on here.  We did not see this pattern during past snapshot events.  There’s a big washout at the north edge of the golf course, and two construction sites in this area, but phosphorus was low and transparency was high on May 17, so the nitrate spike seems unrelated to erosion.  Do we need to start pushing for riparian buffer strips near golf courses?  Do we need to pay more attention to fertilizer spills?

erosion on Ioway Creek near Coldwater Golf Links

They say it’s rude to point.  Let’s not point fingers, they say.  And for the most part, I take that to heart and do programs emphasizing that we all live in a watershed and there are things that everyone can do to improve water quality, whether that’s planting cover crops or picking up after your dog.  But it’s also rude to ask five responsible landowners to invest time and money to protect water quality and have their efforts cancelled out by one irresponsible neighbor, or one preventable accident.  This concept is called The Disproportionality Conundrum in the environmental science literature and it’s something we need to talk about.

Volunteers in the Creek All Week

Volunteers in the Creek All Week

Trash Cleanup

Ioway Creek got some love from the community last week.  On Saturday May 21, a group of seventeen volunteers (plus another four helping on land) loaded nine canoes with trash as we floated from Brookside Park down to S. 16th Street in Ames.  We hauled out 14 tires and 1,560 pounds of other trash including 3 shopping carts, a tent, and two bicycles.  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.  A few people got wet, everyone got dirty, my muscles are still sore, but we all had a good time on the river!

volunteers testing water quality

Citizen Science

On Tuesday May 17, fourteen volunteers tested water quality in Ioway Creek and its tributaries. This is the fifteenth Spring Watershed Snapshot, and the fourth that Prairie Rivers organized. Thanks to the Outdoor Alliance of Story County for help with supplies.  This year, some volunteers were already doing regular monitoring of a site for Story County Conservation and adjusted this month’s schedule to coordinate, or picked up a few extra sites. If we include other watersheds and other days tested during the same week, the count is 22 volunteers (and also some Story County Conservation staff) and 47 sites in Story, Boone, and Hamilton counties.

We scheduled the event for a weekday this year to coincide with Polk County’s snapshot, so while the event was less social than it sometimes is (volunteers could pick up a kit any time on Tuesday and test their assigned sites alone or with a friend), they were monitoring as part of a big coordinated effort of the kind that we haven’t seen since before the IOWATER program was cancelled!  In Polk County, 75 people covered 115 sites!

A table with our findings are shown below, and a map of the sites can be found here.  On Tuesday, the water was clear and phosphorus was low at all our sites.   Chloride was highest and nitrate lowest in creeks with more urban watersheds.  Dissolved oxygen fell into the “fair” range at several sites in Hamilton County, as well as the south fork of Worrell Creek in Ames.  Nitrate was 10 mg/L or higher at most sites, but reached 20 mg/L in the middle sections of Ioway Creek and several rural tributaries.  I did some followup testing to make sense of the high nitrate levels at Duff Ave, more on that later.

Thanks to all the volunteers who spent some time in a creek last week!

Rivers Routinely Ruin Riprap Revetments

Rivers Routinely Ruin Riprap Revetments

This island in the middle of the South Skunk River used to be riprap armoring the outside bend.  (I turned my kayak upstream to take this photo).  Rick Dietz pointed this out to me during the Skunk River Paddlers’ annual “Pancake Paddle” on April 2.  Five of us bundled up and enjoyed canoeing and kayaking from South 16th St in Ames to Askew Access near Cambridge.  Back at the office, I looked at some aerial photos.  The riprap near Ken Merrill Road must have been installed some time in the ’90s, but by 2009, the concrete had slumped to the bottom of the channel and the river had started carving away the bank behind it.

aerial photos showing stream movement

The Skunk River south of Ames reflects an old attitude toward rivers.  We straightened the bends in the river, which made the water go faster.  The faster current caused banks to cave in, so we dumped concrete (and sometimes old cars) on the banks to armor it.  This didn’t always work.  Hopefully we’ve learned something from these failures and are exploring how to manage rivers by working with nature:  this can include setting aside floodplain areas to allow rivers to meander, using stumps and rock structures to redirect the current away from unstable banks, reshaping the channel so that the river can overtop its banks and dissipate its energy without causing property damage, and protecting the banks with a mix of rocks and native vegetation.  Riprap and levees should be used sparingly.

As for the paddling, the water was cold, so water proof gear and dry bags are a must, but early spring on the Skunk is a great time to see birds.  We saw several flocks of mergansers, wood ducks, a yellowlegs, bald eagles, and herons.  We’ve got some nice water trails in Iowa, so take advantage!

The Mystery of the Orange Creek

The Mystery of the Orange Creek

orange colored water in a creek

“Is this pollution?”  I received this photo, taken at 1PM on March 24, from Ames High School student Oskar Niesen.  I met Oskar and other students in Mr. Todd’s environmental science classes for the first time in February, when we talked in the classroom about issues and solutions in Iowa waterways.  The class was interested in testing water quality, so I met them again at the creek on March 22 and showed them how.

Let’s call the site of the incident “Ames High Creek.”  It joins Ioway Creek near the disk golf course and originates with a 60 inch storm sewer pipe near the Richard Pohl Memorial Preserve (Ames High Prairie).  The pipe drains several neighborhoods in north Ames (including mine) that were built before modern development ordinances requiring detention ponds.  I’ve taken video of the torrent of water that comes out of the storm sewer after a heavy rain, and have seen the bank erosion it causes.  I’ve also tested the water after rains and found high levels of bacteria, sediment and phosphorus levels in this creek during heavy rains.  If people don’t pick up their trash, pet waste, or yard waste, there’s nothing to stop it from washing into to the creek.  So I was prepared to answer “yes, the orange-brown color must be pollution.”

Later that evening, I visited the site and chatted with Jake Moore and Liz Calhoun with the City’s stormwater program.  If someone had let muddy water wash off a construction site, or someone was pouring chemicals down the storm sewer, this would violate city ordinances and they would be the people to check up on it.  But the timing wasn’t consistent with construction site runoff.  There hadn’t been more than trace rain since Tuesday March 22nd.

orange stain at water's edge

 Oskar had talked with a geology professor at Iowa State (Dr. Elizabeth Swanner) and suggested another possibility: iron oxide (rust), perhaps formed by naturally occurring bacteria.  As Oskar explained “there are generally 3 types of iron oxide formations. One is a stain that we see now, the second is called flocculent iron which is a cloud that I saw then, the third is an iridescent film on the top.  Bacteria tend to form all three.” At 5:00 on March 24, when I followed up on Oskar’s tip, the water had cleared up and there was no iridescent film, but there was stain on the rocks and at the water’s edge all the way up to the storm sewer outlet.

water flushed from hydrant

Hydrant flushing is done every year with the express purpose of flushing out iron oxide and other mineral deposits that can clog water mains.  Liz Calhoun confirmed that crews flushed hydrants in neighborhoods connected to this storm sewer on March 24.  A little rust in water can stain laundry but is harmless to people and fish.  A release of drinking water can kill fish if it causes a sudden temperature change (this happened last summer when a water main broke) but in this case, we think there’s nothing to worry about.  Mystery solved!  The only thing more gratifying than working with curious young people and helpful colleagues is a happy ending for water quality!

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