Watershed maps tell us how big the solutions have to be

Watershed maps tell us how big the solutions have to be

You may have seen a “Swimming Not Recommended” sign at an Iowa lake this summer. In order to prevent those signs from going up, the first step is often to find the watershed or “beach shed.” That may sound like the place you go to change into your swimming suit or store your boat, but in this case we mean the land area that drains to and influences a given body of water.

For example, while Hickory Grove Lake in Story County is only 100 acres, the phosphorus that stimulates algae blooms could be washing into the lake from over 4000 acres in its watershed. Farmers and homeowners in the watershed have been working since 2008 to install conservation practices and fix up septic systems, with the help of Story Soil and Water Conservation District and other partners. When the rains come and water refills the restored lake, these efforts will ensure that the lake doesn’t refill with algae.

Water quality solutions can get a little smaller and more manageable if we can focus in on a problem area with a smaller watershed. As part of a water quality improvement plan (TMDL) for beaches, the Iowa DNR has done detailed studies of Hickory Grove Lake and five other lakes. They found that in all cases, fecal bacteria (the other cause of beach closures) were higher in the wet sand than in the water, higher at the shoreline than the deeper parts of the swimming area, and lowest outside the swimming area. It means that we can focus on just the 2.8 acres that drain directly to the beach at Hickory Grove (the “beach shed”, as the DNR put it) rather than in the entire lake and its watershed. Solutions for this beach and the other five include regular grooming of the sand, making the shoreline less attractive for geese, and redirecting or treating polluted runoff from parking lots and picnic areas.

But if the water quality problems are big enough (like the dead zone in the Gulf of Mexico) then our solutions need to get bigger. All Iowa is part of the 1,151,000 square mile Mississippi River watershed, so all Iowans can do their part to keep nitrogen and phosphorus from washing downstream.

Watershed Matchup #2: Clear Creek VS Clear Creek

This post is part of a series for 2019 Watershed Awareness Month, comparing water quality in a pair of local creeks to learn how land and people influence water.

Clear Creek @Hyland on May 18Clear Creek@ Hyland on May 24
Transparency > 60 cmTransparency of 1 cm
Orthophosphate 0.1 mg/LOrthophosphate 5 mg/L

Clear Creek was true to its name on May 18 when the Squaw Creek Watershed Coalition did its spring water quality snapshot.  Long-time member Ed Engle and three Ames High School students (Wil, Becca, and Nate) filled a transparency tube to the top (60 cm) and the secchi disk at the bottom was clearly visible.  A week later, Rick Dietz tested the same location after a 1.7 inch rainstorm and couldn’t see the disk until he’d poured out all but 1 cm of the water!

Phosphorus in Clear Creek was high enough we had to break out the high range comparison vials!

Water quality can change rapidly.  Sediment* in the water spikes during and after a big rain storm.  So does phosphorus and E. coli.  Nitrate and chloride show strong seasonal patterns.  While some of that variation may average out in a big dataset, when streams are sampled less often, it can be tricky to make an apples-to-apples comparison.  That’s why water quality snapshots—multiple streams sampled on the same day—are so valuable.

*measured as clarity, turbidity, or total suspended solids

The Coalition has been monitoring Clear Creek since 2007.  It normally has pretty good water quality, with orthophosphate near the outlet averaging 0.2 mg/L and transparency averaging 43 cm.  23% of the riparian area is forested (Pammel Woods, Munn Woods, and Emma McCarthy Lee Park) so that’s part of the reason.  Another reason is the efforts of some farmers in the watershed.  Jeremy Gustafson has been improving his soil and protecting water through his innovative use of cover crops–planting soybeans into living rye and using diverse mixes after oats.

Farmer Jeremy Gustafson shows members of the Squaw Creek Watershed Management board how cover crops have improved his soil.


Still, there’s room for improvement.  Nitrate levels average 5.7 mg/L in Pammel Woods, and 7.5 mg/L at the Boone-Story county line.  (For reference, nitrate was historically less than 2 mg/L). And as the “gully washer” of May 24 shows, the relatively flat “Des Moines Lobe” region of Iowa is not immune to soil erosion!  More no-till, cover crops, and prairie strips could further reduce erosion.  More sediment ponds, wetlands, and buffers could prevent sediment from reaching the creek.

A creek sign on the Lincoln Heritage Byway (Ontario Rd near the county line)! You can’t get more Prairie Rivers of Iowa than that!  The creek was out of its banks.

Clear Creek, College Creek, and Worrell Creek all start in Boone County and join Squaw Creek in Ames.  We’ll continue to support conservation practices in these watersheds through our Small Landowner Assistance project (wrapping up this year) and our National Fish and Wildlife Foundation grant (just getting going).  If you live or farm west of Ames and are thinking about conservation, or know someone who does, give us a call!

Watershed Matchup #1: Long Dick Creek VS Bear Creek

This post is part of a series for 2019 Watershed Awareness Month, comparing water quality in a pair of local creeks to learn how land and people influence water.

Long Dick Creek and Bear Creek both start east of Ellsworth and join the South Skunk River between Story City and Ames.  Both have agricultural watersheds with thousands of acres in both Story county and Hamilton county.  Yet one is dirtier than the other.   You might wonder why…

Hey!  Wipe that smirk off your face!

“Long Dick” was the unfortunate nickname of a tall guy named Richard who explored the land near the creek when it was still wild prairie.  “Bear Creek” was named because an early settler shot a black bear nearby.  Since the 1860s, the prairie and the bears have disappeared and the man’s nickname has acquired other meanings, but we at Prairie Rivers of Iowa are serious about our water and our history and will have no giggling, thank you very much!  If you have a problem with “Long Dick Creek”—or for that matter, “White Breast Creek,” “Squaw Creek“, or “Drainage Ditch 5″—you can follow the example of Newton High School and take it up with the US Board on Geographic Names.

Anyway, I was out doing some water testing this week and noticed some pretty high nitrate levels in Bear Creek (10mg/L) and even higher nitrate in Long Dick Creek (20 mg/L) .  The same pattern held when I sampled in June of last year, using more precise equipment: 13mg/L in Bear Creek and 21 mg/L in Long Dick Creek.  For reference, the drinking water standard for nitrate is 10 mg/L.

These are similar creeks with similar watersheds, although Long Dick Creek does have more livestock.  I will wager that the difference is what’s been done in the land along the stream.  For over a decade, researchers at Iowa State University have worked with farmers along Bear Creek to plant riparian buffers, study their effectiveness, and share the lessons nationwide.  Long Dick Creek is pretty typical for Iowa streams.  The stretch pictured (at 115th St) has a nice grass buffer, but there are other stretches without much space between the crop field and the water.  Doing some quick GIS analysis with 2011 landcover, it looks like Bear Creek has more buffers, wider buffers, and better buffers, and that seems to have made a difference for water quality.

Long Dick CreekBear Creek
23,500 acre watershed18,500 acre watershed
90% cropland in the watershed86% cropland in watershed
116,919 animal units of swine in watershed32,536 animal units of swine in the watershed
147,500 animal units of poultry in watershed18,000 animal units of poultry in the watershed
 73% cropland within 100m of creek63% cropland within 100m of the creek
2% forest within 100m of creek8% forest within 100m of creek
6% grassland within 100m of creek11% grassland within 100m of creek
8% pasture within 100m of creek8% pasture within 100m of creek
21 mg/L nitrate (June 16, 2018)13 mg/L nitrate (June 16, 2018)
0.8 mg/L orthophosphate0.6 mg/L orthophosphate


male dickcissel (photo credit: Rebel At on Wikipedia)

Prairie Rivers of Iowa recently received a grant from the National Fish and Wildlife Foundation that will give us an opportunity to talk with landowners near Long Dick Creek and two other small watersheds about conservation practices that benefit both wildlife and water quality.  We may never see a bear along Bear Creek (and I’ll bet the residents of Roland are fine with that), but with a few more prairie plantings to provide habitat, we’d have a good reason to rename the little stream east of Story City to “Long Dickcissel Creek.”