A report completed by a consulting firm in 2022 on plant diversity in Swan Pond Park in Riverside recommends an aggressive approach targeting invasive and undesirable native species, but village officials say they will continue to take a conservative approach to managing that evolving natural area in Riverside’s downtown.
Last year, the Riverside Landscape Advisory Commission enlisted Waukegan-based Integrated Lakes Management (ILM) to deliver a monitoring report providing baseline data on the park’s plant species diversity and recommend ways to improve it.
The conclusions in that report are also part of the LAC’s updated Master Landscape Plan for the village, which was presented by commission members to elected officials at the March 16 village board meeting.
ILM recommended that Riverside “should include aggressive [herbicide] treatments throughout the site, targeting all invasive species and many undesirable native species,” calling that approach “the most ecologically sound option.”
However, local officials aren’t so sure that approach would be for the best. Not only is that approach the costliest, at around $13,350, but it would result in a visually unappealing landscape, even if temporary, and open the door to unintended consequences.
“An aggressive approach is not necessarily better,” said Village Forest Michael Collins, who has conducted controlled burns of Swan Pond in two consecutive years, the last being March 29.
Collins says Swan Pond remains a hydrologically volatile area, one prone to flooding during a time when significant storms have come more frequently. In the past decade, Swan Pond, a low-lying basin along the banks of the Des Plaines River, has flooded repeatedly in all seasons.
Some of those floods have caused significant damage to the park’s landscape, and were the reason the village decided to abandon its use as an active recreation area to a natural area, with a significant wetlands component.
“You can push and pull and place demands on Mother Nature all you want, but Mother Nature is going to do what she wants,” Collins said. “To me, it’s important to have a measured approach to match how the natural systems work.”
Lisa Lambros, the chairwoman of the Landscape Advisory Commission, agreed with Collins’ assessment of ILM’s recommendations.
“Even if, all of a sudden, we had a pile of money, the problem is if you kill off even what’s existing and you get a flood, you could actually put the site in even worse condition,” Lambros said.
The controlled burns are part of that measured approach, creating natural condition in which native plants can compete with invasives and undesirable native species. For the past couple of years, Riverside has also used ILM to apply herbicides in a targeted way to kills invasives such as canary reed grass. But those strategies alone are not a panacea.
The LAC’s updated master plan noted that the 2022 herbicide applications were not followed by underplanting with desirable species, leaving undesirable plants to occupy the vacated spaces.
In response the village is adopting ILM’s recommendations to continue with regular controlled burns and herbicide treatments, but the village is also now seeding strategic areas after those treatments.
Collins said he’s judicious in his application of the mesic plant seed, because it’s very expensive since it has be collected by hand for use in specific locations. A 30-pound bag, enough to cover 1 acre, said Collins, costs $900.
He typically stays away from the lowest-lying areas of the park, where flooding is more prevalent.
“We want to put quality plant material into that system,” he said.
Avoiding the most aggressive approach in Swan Pond may also be the result of lessons learned from 2017, when the village spent nearly $30,000 to plant 10,000 plant plugs, comprising 16 species, into the wetlands area of Swan Pond.
The LAC’s 2023 Master Landscape Plan noted only eight of the 16 species planted in 2017 had survived the conditions there. The ones that did survive and thrive there today are plants like bullrushes, sedges and sweet flag.
“The ultimate lesson was that the village board is committed to moving forward and monitoring these sites,” Collins said. “I think it also demonstrates the site will tell you what it wants.
“[The 2017 planting effort] was well-intentioned, but when to comes down to it, we could have used more mesic plant material.”
Riverside Public Works Director Dan Tabb said the village is committed to continue using ILM to apply herbicides and monitor the evolution of Swan Pond. The village’s annual budget for that effort is about $6,500.
We’re not going to force feed the site something that won’t keep for the long term,” Tabb said. “We’ll amend the plan annually depending on what we see.”
