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 Creek||Bear Creek|
|23,500 acre watershed||18,500 acre watershed|
|90% cropland in the watershed||86% cropland in watershed|
|116,919 animal units of swine in watershed||32,536 animal units of swine in the watershed|
|147,500 animal units of poultry in watershed||18,000 animal units of poultry in the watershed|
|73% cropland within 100m of creek||63% cropland within 100m of the creek|
|2% forest within 100m of creek||8% forest within 100m of creek|
|6% grassland within 100m of creek||11% grassland within 100m of creek|
|8% pasture within 100m of creek||8% pasture within 100m of creek|
|21 mg/L nitrate (June 16, 2018)||13 mg/L nitrate (June 16, 2018)|
|0.8 mg/L orthophosphate||0.6 mg/L orthophosphate|
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.”