Brown’s Creek fish hoping for a big chill

This is a story about trout. It’s also a story about local history, changing landscapes, and people trying to do the right thing.

Somewhere in the wetland dappled landscape near the now-closed Withrow Elementary, water begins to gather and form a stream we now call Brown’s Creek. The stream flows through soggy fields in Grant and Stillwater Township before it eventually plunges into a deep, wooded gorge in northern Stillwater, then on to the St. Croix River. Because it is fed by groundwater along the way, the creek is cold and clear. Rainbow darters live there, as well as rare species of aquatic invertebrates known to only the most dedicated biologists.

20181009_085808 — Students from Stillwater Area High School sample Brown’s Creek for macroinvertebrates and other aquatic animals with help from the Washington Conservation District.

Over the years, people have diverted the creek into Lake McKusick and then back again. It’s been used to turn the lumber mills and provide drinking water for Stillwater residents. They began stocking the stream with trout for fishing in 1950 and later created a new channel along the Minnesota Zephyr rail line (now the Brown’s Creek Trail) to replace a meandering pathway through a wetland north of McKusick and provide better habitat.

1998-2000 were glory years for the trout. Then, in 2002, the Minnesota Pollution Control Agency added Brown’s Creek to the federal list of impaired waters after populations of trout and aquatic insects began to plummet. The newly formed Brown’s Creek Watershed District set to work to figure out what was wrong and then nurse the stream back to good health.

Every few years, the watershed district solves another piece of the puzzle. In 2001, the district completed its Trout Habitat Preservation Project, which alleviated flooding in the Goggins-School Section chain of lakes (Hugo and May Twp.) by routing excess surface water near the headwaters of Brown’s Creek through a series of created wetlands and an infiltration basin designed to filter pollutants and recharge groundwater.

BCWD_-_THPP_2004_MAWD_Project_of_the_Year-small_Web — The Trout Habitat Preservation Project helped to alleviate flooding and protect Brown’s Creek.

The district has completed stream improvement projects at the Stillwater Country Club, Oak Glen Golf Course, Countryside Auto, and along the Brown’s Creek Trail. They’ve worked with homeowners living near Oak Glen Golf course and Brown’s Creek Park to install raingardens that filter stormwater, and helped the City of Stillwater to install a below-ground system at Brown’s Creek Park that cleans and cools runoff water from the parking lot and Neal Ave. before it enters the stream. Every year the water is a little bit cleaner and a little bit colder.

Part of the challenge is that trout and the other fish and insects that live in Brown’s Creek are extremely picky. When water temperature creep above 65°, the fish stop reproducing, insects die, and eventually the trout do too. Thanks to the many clean water projects completed, water temps in Brown’s Creek have stayed just cool enough in recent years for trout to begin surviving and reproducing again. Now, the Brown’s Creek Watershed District is looking for additional opportunities to cool the water just a little bit more.

20181130_MAWD_Riparian Shading_Final_Page_06 — During 2017, the water temperature in Brown’s Creek was never above 23.9°C, the critical temperature above which brown trout start to die. There are still times during the summer when the water is warmer than 18.3°, however, and this can cause stress for trout and other fish in the creek.

During this year’s Minnesota Association of Watershed District’s conference, researcher Olivia Sparrow shared what she’s learned about shade after analyzing miles of stream between Withrow and Stillwater. Sparrow used a special camera to take hemispherical photographs along different stretches of Brown’s Creek and then analyzed the amount of shade present at different times of the day. Deep woods, like in the gorge, provide the most shade, but Sparrow found that even solitary trees provide up to 80% shade if they are planted a few feet back from the stream. Tall grasses along the water’s edge provide 10% to 61% shade as well. Based on her research, Sparrow estimates that the Brown’s Creek Watershed District could lower stream temperatures an additional 0.16 to 0.52°C by working with landowners to plant trees and native grasses in targeted locations along Brown’s Creek.

20181130_MAWD_Riparian Shading_Final_Page_30 — After analyzing the amount of shade along different stretches of Brown’s Creek, Olivia Sparrow identified key locations where planting more trees or grasses would help to lower water temperatures.

This is a story about people trying hard to restore a stream, but it’s also a story about trout. In 2016 and 2017, the Minnesota DNR conducted fish surveys in Brown’s Creek in the gorge and near Oak Glen. Not only did they find numerous adult trout swimming happily in the stream, but also they found young trout, which is evidence of reproduction. Best of all, was a special surprise hiding deep inside the gorge. There were four rainbow darters, a native species only found in exceptional streams. The trout and the darters living in Brown’s Creek are beginning to enjoy their long awaited chill.