“Dry Creek restoration to improve hydrology, habitat” was published in the Wyoming Tribune Eagle Sept. 4, 2021.
By Barb Gorges
Jeff Geyer is fixing Cheyenne’s Dry Creek.
First, how did it get its name? Jeff, Laramie County Conservation District water specialist, told me that unlike Crow Creek, our other stream that starts in the mountains, Dry Creek starts somewhere on the F.E. Warren Air Force Base. He said it never had much of a channel, with the water frequently spreading out in flat, temporarily marshy areas and percolating into the water table below as it flowed after a rain or snow event.
Fast-forward 160 years. The Greenway now follows Dry Creek as it crosses northern Cheyenne west to east, parallel to Dell Range Boulevard. At North College Drive it heads southeast to the new East Park and crosses under I-80. It joins Crow Creek near where the sewage treatment plant is today on Campstool Road.
What’s changed is the Dry Creek watershed which drains two-thirds of Cheyenne. More land surfaces surrounding the creek have been paved and built on over the last 30 to 40 years as Cheyenne expands. Jeff says you can see the change on Google Earth (use the free Pro version you can download).
Snowmelt and rainfall aren’t absorbed by pavement and roofs, so they run off into Dry Creek, making much higher flows. Higher flows are faster. Faster flows are straighter. Straighter flows have more energy to erode the soil. Between Campstool and I-80, that energy cut 5-foot deep banks and sent good soil into Crow Creek where it gets deposited in the downstream reservoirs—not good for reservoirs, or the fish in Crow Creek.
In 2019, Jeff started to fix a small section of Dry Creek that will make a difference. The idea is to slow the creek down by increasing its sinuosity which will reduce the energy of the water. The water flow needs to look more like a traveling snake—looping to one side and then to the other, rather than a straight stick.
Mathematically, a straight stream has a sinuosity of 1—the ratio of the distance the water travels is 1 to 1 with the length of the valley. Jeff would like to see a sinuosity of 1.2 or 1.4, meaning that in a 100 feet of valley length, the water would loop an extra 20 to 40 feet.
The banks of a sinuous stream will still erode a bit, but much of the dirt will be deposited in the next curve—slow moving streams can’t carry as much soil suspended in the water.
While some earth work was required to reduce the 5-foot cutbank in places to give Dry Creek access to the flood plain during rainfall or snowmelt events, much of the sinuosity building is being done with willow stems, logs, posts and stakes.
At just the right location and angle in the stream bottom, Jeff and volunteers pounded in stakes in a line and then wove willow stems, forming a “Beaver Dam Analog.” The willows were from a nearby location where they die back and new willows continue growing.
The woven willows are like snow fence that slows the wind, making the snow drop out into drifts. This structure slows water carrying dirt so the dirt will drop and form a bar where willows will grow, and their roots will stabilize the stream bed. There is already a nice stand of coyote willows in one spot.
Up on the flood plain are “Post Assisted Log Structures.” Logs are pinned to the flood plain to make a rough passage that will also slow water down.
Long term, slower stream flow will allow more water around the creek to be absorbed and stored. That underground water flows like surface water and will eventually resurface in the creek, recharging it. Jeff is hoping for a little water to be always in Dry Creek—maybe it will need a new name.
Changing Dry Creek’s hydrology, Jeff also expects to provide the moisture needed for more diverse vegetation for wildlife habitat. Mule deer and ermine have been seen. Cheyenne Audubon members have been making bird observations. Lorie Chesnut, a member, was instrumental in obtaining a $3000 grant through the National Audubon Society’s Western Water Network Grants this year that paid for the stakes and native plants.
As Jeff surveyed the conservation district-managed pasture that surrounds the first phase of the hydrology project (and a second phase that has just begun to the south), he frowned at all the 6-foot-tall mullein stalks and the other non-native weeds. Much more work will be required to transform the pasture into prairie more useful to ground-nesting birds and other wildlife, bringing it back to its formerly lush and flower-filled self.
Cheyenne Bird Banter 