As Lake Decatur turns 100, city gets ‘proactive’ with watershed management

The $92 million dredging of the lake, started in 2014 and completed in 2018, was both cosmetic — clearing it of sediment that quite literally muddied the waters — and functional, restoring capacity that had been lost over several decades and made the city more susceptible to droughts.

“The ‘drought of the century’ happened more than once,” Mayor Julie Moore Wolfe said of the need for the dredging project, which was the largest public works project the city has ever undertaken.

Moore Wolfe recalled that “you could walk across the lake in a lot of places” during the drought of 1988. Another in 2012 led city officials to impose the most severe water restrictions in Decatur history, including a prohibition on residents washing their cars or mowing their lawns.

The dredge successfully removed nearly 7,000 acre feet of sediment from the basin of the lake, increasing water storage by 30% and deepening it by six feet in some places.

“We’ve done all we can physically to the lake to make it as deep and as large as possible to store water due to dredging,” said water production manager Keith Alexander. “But dredging comes at a huge financial cost. The city issued numerous 20-year bonds to pay for all of that dredging … let alone paying the interest.”

As the lake marks its centennial, protecting that investment has become a paramount priority for city leaders. In fact, creating a coordinated plan for Lake Decatur management is among the seven strategic goals explicitly laid out by the Decatur City Council.

With a May 2021 city-commissioned report finding that more than $1 million worth of sediment seeps into the lake every year, a rate that would result in the loss of all dredge storage gains in less than a half-century, city staff and outside watershed consultants on retainer have laid the groundwork for a “much more proactive” approach to watershed management and protection.

“So what I’ve called it is that we’re currently doing a supercharged effort,” Alexander said. “It is astronomically larger in terms of dollars that the city is willing to commit and the staff time that the city is willing to commit to forward these watershed conservation efforts.”

This approach, city leaders hope, will negate the need for further large-scale dredging projects in the future while protecting the water quality and ensuring that ample supply remains for customers and as a tool for economic development.

In February 2020, the city entered into an agreement with Springfield-based Northwater Consulting for planning and implementation of a long-term strategy to reduce the runoff of nitrates and buildup of sediment into the lake.

In addition to setting up monitors for…