On a scenic playground overlooking Lake Springfield Erin Heady watches as her two boys, ages 2 and 4, jump down a slide.

"We love coming to the playground," she said. "It's just a great view."

The family lives in Nixa, but Erin says they make frequent trips to Lake Springfield to enjoy an area known for fishing, hiking and recreation.

"My oldest child has high functioning autism so I found that smaller parks and more intimate settings are easier," she said.

This popular 318-acre lake though wouldn't even exist had it not been built as a cooling reservoir for the James River Power Station.

Built in 1953 with other units added through 1970, the James River facility is Springfield's oldest remaining power plant, providing electricity during a critical time of growth in the city when the population went from 67,000 in 1950 to 120,000 by 1970.

"There's a lot of businesses and opportunities that would not have existed had it not been for the construction of a power plant like that," explained City Utilities spokesperson Joel Alexander. "

Originally the plant used natural gas to produce power. But in the late 1970's when the energy crisis hit the five-unit facility was repurposed.

"The government said 'Quit burning natural gas, we need to have that for other uses, switch to coal,'" Alexander said. "We switched all the units to coal and then not too long ago we switched them all back to natural gas. We also did some tests there with renewable resources so it's an historic place not only for City Utilities but for Missouri and the midwest."

In 2015 when the plant switched back to coal, three of the five units were also shut down as the industry continued to shift towards alternative sources and the plant became less cost-effective.

"It truly has served its useful life purpose for City Utilities," Alexander said. "There's no sense in putting any more money into this when we're looking at the future. We've seen renewable energy decline in price and we've got some opportunities for renewable energy right in our backyard with our own solar farm. We've had our landfill gas project since the early 2000's and we're exploring more options all the time. We are able to bring in wind power now which took us a while with the transmission system in the United States but those barriers have gone away and we're able to do a lot better than we were."

How much better?

Five years ago renewable energy made up only eight percent of C-U's generation sources compared to 77 percent coal.

Now, it's 40 percent renewable energy and only 28 percent coal.

So the closing of the James River plant is really "The passing of the torch to a new era of power generation," Alexander said.

It will take about a year to totally decommission the facility and while Lake Springfield isn't going anywhere, C-U hasn't decided what to do with the silent sentinel looming on the horizon that made it possible.

"That's probably up for another generation to decide," Alexander said. "If you look across the country you see other areas that have taken older generation sites and turned those into malls, breweries, restaurants. It just depends on what the growth and economy demands for a community like that."

The city also gets power from its coal burning Southwest Power Plant and from outside market purchases as part of the 14-state Southwest Power Pool which C-U joined five years ago.