Ten months ago, a handful of volunteers and Riverside public works employees spent a hot August afternoon planting plugs of between 15 and 20 species of wetlands plants in the lowest area of Swan Pond Park – in and around the drainage culvert installed by the U.S. Army Corps of Engineers in 2012.
They planted around 10,000 plugs in all – their installation delayed twice by rains that flooded the park – as part of a concerted effort to eliminate the standing water that’s become so common in the past five years.
The jury is still out on how well the plants have taken and what to do next.
“It’s a little too early to predict what to do next until we see what happens,” said Cathy Maloney, chairwoman of the Riverside Landscape Advisory Commission, which was charged with coming up with a solution to the problem.
Looking out at the park from the culvert, there are clearly areas where the plants are coming back up, apparently unharmed by the flooding. Other patches of ground look barren, leaving officials wondering if those plants may pop through the river silt that’s been deposited at the low spot in the park after things dry out.
But it’s possible many plants just couldn’t handle being submerged so many times for so long.
“I still think it’s early, because of the weather events we’ve been having,” said Riverside Public Works Director Edward Bailey, as thunder echoed in the distance during an interview in the park on June 8 and raindrops drizzled from gray clouds overhead.
“What we clearly have to wonder about is what’s going to happen with this area that gets the most residual water,” Bailey said. “Hopefully the big rain events will let off for a while.”
Two days after the interview, the low area of Swan Pond Park was again under water.
Since April 2013, when record-setting river crests flooded parks and residential areas near the Des Plaines River, Swan Pond Park has been inundated over and over, with flood water covering the low area near the culvert for days and even weeks.
Since the reeds and sedges were planted in August 2018, the area has flooded repeatedly after heavy rains, throwing in doubt whether the plants would survive. Two months after they were planted, the park flooded and the village took steps to pump it out to save the plants.
Some residents believe the park is filling up via a drainage pipe connected to the culvert, saying river water is back-flowing through it, into the park.
Public Works Director acknowledged the complaint, but said he’s never witnessed that himself.
“I’ve never been here when there’s been any indication of waters back-flowing into this swale,” Bailey said. “I wouldn’t bet my life on it, but any time I’ve ever checked it there’s just no indication.”
What Bailey says he has seen with his own eyes is the river overtopping the stone retaining wall at a low spot along the bank, a few hundred feet south of the little plaza area along the walking path.
Another low spot exists near the former location of the Fairbank Dam, the so-called “little dam” toward the south end of Swan Pond Park.
The water overtops the wall when the river level reaches more than 7 feet, which is considered “flood action” stage by the National Weather Service. Since June 2015, the Des Plaines River at Riverside has risen higher than 7 feet on six occasions.
On June 10, the river crested at 6.43 feet. It didn’t overtop the banks, but the low spot near the culvert flooded just the same.
The Des Plaines has hit moderate flood stage twice in four months between October 2017 (which led to pumping Swan Pond) and February 2018.
Looking at National Weather Service data, high-water events are happening more frequently now than ever before. Between 1944 and 1965, the Des Plaines River crested above the 7-foot mark just seven times, just two of those reaching 8 feet and none reaching 9.
Between 1966 and 1986, there were 13 times the Des Plaines hit at least 7 feet, and the river crested at 7 feet or more another 13 times between 1987 and 2007. During the 63-year period from 1944 to 2007, the river rose to 9 feet just twice.
Since 2008, the river has crested above 9 feet on three occasions, hitting an all-time record in April 2013 at 11.42 feet. Seven other times, the river rose to more than seven feet.
Of the 10 flood-level events since 2008, six of them have been crests that have topped 8 feet.
There won’t be any additional planting in 2018. For officials, it’s a wait-and-see year, and a year where the village wants to keep a handle on controlling weeds, which are sprouting happily alongside the new plugs.
“It’s the weeds that have everybody concerned,” said Maloney, “because they can crowd out the new plants.”
The village has responded by hiring a firm, Semper Fi Land Services, to control the weeds there. But the area has been under water so often, the firm hasn’t been able to do much work there yet.
“It dried out enough for us to make one management visit,” said Shawn Sinn, a Riverside resident who is vice president of Semper Fi Land Services. “We were able to hit some invasive species at that time.”