As the weather gets warmer, Minnesotans start to head outdoors to soak up the sunshine and enjoy a cool breeze. But even when it's nice outside, enjoying the view from the deck can be hard when the pond in the backyard is cloudy, brown and filled with sludge.
The city receives about half a dozen complaints from residents each year about the appearance of the ponds, which are cloudy, algae-filled and unsightly. Two years after instituting a new utility fee designed in part for the purpose of maintaining the ponds, the city is starting to clean them up.
Northfield City Councilor Erica Zweifel, who supports the new maintenance plan, feels that it's important for the city to maintain its stormwater pond system.
"Some of these stormwater ponds have filled in to the point of no longer functioning as storm water infrastructure," Zweifel said. "These ponds need scheduled maintenance to retain their functionality as part of our storm water system."
The area ponds, which run directly into the Cannon River, are designed to store runoff and slow the speed at which excess water reaches the river. This prevents flooding and decreases the volume of pollutants that seep into the Cannon River.
But over time, the ponds can accumulate too much sediment, which includes sand, grass and leaves that blow into ponds from the properties that surround them. High levels of runoff and sedimentation not only turn ponds into eyesores, but deter the ponds from holding as much water and fulfilling their original purpose.
This fall, the city will start maintenance work on city stormwater ponds to restore them to optimal functionality.
In 1984, the Cannon River was designated as "wild and scenic" by the state, which brings a strict management plan the city needs to follow. The rules of the management plan, according to the Minnesota Department of Natural Resources, "work together with local zoning ordinances to protect the rivers from pollution, erosion, over-development, and degradation." The goal of the pond maintenance project is to restore Northfield ponds and the Cannon River to the same runoff levels measured in 1984.
According to Brian Welch, engineering resources manager for the city of Northfield, the Cannon River and the ponds that flow into it have seen a significant increase in sedimentation and runoff since then.
"We knew we needed to reduce the runoff levels to 1984, so we had to go back and look [at the Cannon River]," he said. "Now we know we need to cut the levels in half. We knew that a number of ponds needed work."
With that in mind, Welch and his team have proposed a pond maintenance and rehabilitation program designed to return Northfield ponds to their original states.
In a plan to dredge the ponds and restore them to their original dimensions, six have gotten priority: Rosewood, Grant Park, John North Park, Hidden Valley and Sibley View (East and West). Rosewood, located at the corner of Heywood Road and Creek Lane, is about 10 years old and has about 29 percent sedimentation. It will cost around $58,600 to maintain.
Funding for the project comes from the city's stormwater utility fee, which was established in 2008. The fee is paid by each city property holder and is part of their monthly utility bill. Currently, city residents with average-sized lots pay about $13 per month. The city will use these funds to clean up approximately one pond per year for the next six years, and will reassess the less-prioritized ponds and the budget after that.
Zweifel believes the expense of dredging the ponds will save money in the future, as upkeep on the ponds will cost less once each pond is restored.
"Once we are caught up on getting these ponds back to a functional state, we can switch to a more constant upkeep plan for all the ponds and save money in the long run, because upkeep is cheaper than the major overhauls that we are facing now," Zweifel said.
Welch estimates that the Rosewood project will take two or three weeks to complete, with only minimal disruption to the streets and neighbors nearby. The pond will look more or less the same from the surface, but will be restored to its original dimensions and capacity. The ability of the ponds to hold as much water as they were designed for is an important part of the city's water maintenance plan. Clearing out the buildup at the bottom of the ponds will allow for better, cleaner drainage into the Cannon River, as well as the possibility of improved aesthetics.
"We want to make sure that runoff is going where it's supposed to," emphasized Welch, "These ponds serve a very functional purpose."
— Reach Intern Kaylin Hreha at 645-1114.