Restoring the creek
Field study contributes to water quality improvement
Environmental field work underway in Soldier Creek will soon address erosion issues leading to poor water quality.
Fort Dodge’s latest water quality improvement project kicked off field work in the stream at 170th Street, north of the city, earlier this week. It’s one of several projects the city has undertaken since 2014 to improve environmental health and water quality at a time where many are trying to get outdoors as much as possible.
Clive-based Impact7G Inc. has been studying eroded creek banks, taking cross-sections of high points in the stream and collecting rock samples to determine the speed and velocity of the water, among many other things, in an attempt to restore the site at the boundary between urban and rural development to its original state decades ago.
As an increase in the number of storms over the last several decades as well as a surge in the typical storm’s intensity has caused more water to rush through the stream faster, creek banks have eroded to the point of collapse in places, according to Judy Joyce, geomorphologist and project manager with the environmental services firm.
“When water is going fast, the creek tries to adjust itself by making the stream length longer,” Joyce said. “If (water) goes too fast, it’ll want to make bends.”
Though a bank caving into a meandering creek might not seem of much consequence, the accumulation over thousands of miles of streams can have detrimental effects downstream in Fort Dodge, the Des Moines River and, eventually, the Gulf of Mexico. As banks erode, they dump silt, clay and sediments carrying nitrates, phosphates, bacteria and e. coli into the stream, affecting the health of fish, wildlife and the natural water bodies that humans rely on.
That sediment flowing long distances during high spring rainfalls has contributed to a “dead zone” in the Gulf of Mexico now the size of Massachusetts, where little or no oxygen kills fish and other marine wildlife, according to the National Oceanic and Atmospheric Administration. In 2017, the dead zone was about 2,000 square miles smaller, comparable to the size of New Jersey (8,700 square miles.)
In the age of COVID-19, as many flock to outdoor spaces as a reliably safe place for socially-distanced recreation, keeping natural resources healthy also has renewed importance for recreation.
“If we want people to touch the water and interact with it, we have to clean it up so the water’s safe,” Joyce said.
The weather pattern changes contributing to the bank collapses, a consequence of climate change, haven’t just affected shorelines of coastal cities — they’re right in Iowa’s backyard.
“Over the last 50 years, we’ve seen more 100-year flood events and more large storm events than we’ve ever seen before,” Joyce said. “You’re getting that one-two punch of bigger storm events plus land use changes that have changed the way the water’s delivered to the system.”
With more pavement, fewer wetlands and more shallow vegetation, water that would have taken more time to filter through the land on its journey to the creek hundreds of years ago now flows in at a much quicker rate.
By determining how much water the stream can safely hold, the environmental firm will implement solutions through a plan to be returned to the city by this fall.
“We’re hoping to stop that erosion and plant species that naturally clean up the water ways,” said Tony Trotter, city engineer. “In the end, we’re just trying to be good environmental stewards and do our part to clean up Soldier Creek and the Des Moines Rivershed.”
The project, which will cost about $1 million, is functionally cost-free to the city thanks to the state’s revolving Clean Water Loan fund. When rolled into the city’s $15.5 million sanitary sewer improvement projects, water quality improvement projects through the state program allow the city to reduce its interest rate, making its payments the same.
“You essentially get a free project,” Trotter said.
This is the fourth project the city has undertaken since 2014. Other projects have been completed at Snell-Crawford Park and Badger Lake at John F. Kennedy Memorial Park.
Improvement plans recommended by Impact7G should be constructed this winter or next summer, restoring pieces of the section that was once a straight stretch of creek about 100 years ago.
Soldier Creek has some nice features, Joyce said, such as gravel substrate that serves as a breeding ground for bugs that feed the fish, abundant variety of wildlife, tree cover and vegetation. Some problem areas already identified include collapsed culverts going into the stream and a lack of sandbars, which remove nutrients and trap sediment to avoid choking the stream.
Joyce said that they may install sand bars, cross veins made of rocks that can reduce the negative affects of high-velocity waters and structures that can improve water and habitat quality.
“It might not seem like a lot to have a couple banks cave in, but over hundreds of thousands of miles of streams, this is going on, and (soil) is going downstream,” Joyce said. “We’ve got to start somewhere.”
This time next year, the stream could be restored to the way it was naturally supposed to function.