I do not typically write about things local to me. Others, like my friend Ted Shideler, do it so much better and more thoroughly than I ever could. However. Sometimes a local story comes along that grabs me by the lapels and will not let go. One of them involves the recent flooding in Central Indiana, and an unexpected safety valve that prevented it from being worse.

Much has been written about the major flooding that Central Indiana experienced last month. On August 11th, hours of heavy rain began to wallop the already saturated central northeast part of the state, mainly along the corridor of the White River. Indianapolis is in the geographic center of the state, and was located there (it is said) in the mistaken belief that the White River was a navigable connector between the Great Lakes to the north and the Ohio River at the State’s southern border. They were wrong – the White River¹ does indeed flow into the Wabash River and then the Ohio River to the south, but following either of its forks to the north gets you only into innumerable small creeks and streams in Randolph County, along the State’s eastern border. But from Muncie and to its south, the White River is a major source of fresh water that gets bigger as it goes south.

The rain that fell on August 11th was at its worst in the areas of two county seat cities to Indianapolis’ northeast (Anderson and Muncie), which were drenched with rainfall of over 11 inches in two days. New Castle, just east of Muncie recorded a one-in-1000-year rainfall of 11 inches in 32 hours. And with so much rain concentrated in the vicinity of the White River, you know what happened next.

The river at Muncie crested at 18.64 feet (over 9.5 feet above flood stage), though short of its 1913 record of over 22 feet.² (Blogger Ted Shideler documented some of the damage there.) Anderson, the next decent sized city downstream from Muncie broke the 1913 record with a crest of nearly 25 feet, or about 15 feet above flood stage. Even though the river widens as it goes south, Noblesville (about halfway downriver between Anderson and Indianapolis) still broke the 1913 record with over 24 feet (more than 10 feet over flood stage). History and experience tells us that heavy rains flood the river and that those floods continue to build momentum as they course downriver through city after city. But this is where the story of 2026 saw an interesting twist.

There is a small creek called Blue Woods Creek that meanders around until it empties into the White River south of Noblesville and not far above the northern edge of the Indianapolis Metropolitan Area. About thirty years ago, that creek was redirected around the northern edge of a large sand and gravel quarry operated by Martin Marietta. Between the quarry and the river, a road called Hazel Dell Parkway was built over it in an area that has experienced explosive residential and commercial growth in that time. What does this have to do with the flood? Just this: The quickly rising river levels caused water to flow backwards up Blue Woods Creek. It rose under the Hazel Dell Parkway bridge and, as water volume continued to rise, it found its way to the edge of the quarry.

Once that flow was established, the power of moving water manifested itself. The water dug deeper and wider as it kept backflushing up the creek in ever greater volumes. And when it came to the sharp northward bend, the powerful current had a better idea and pushed straight into the quarry, where it created some impressive waterfalls as it slowly began to fill the quarry (and some tunnel mines under it). A fellow with a drone captured some of the drama (link here), including the way the supercharged creek destroyed the Hazel Dell Parkway bridge.

By August 17th, six days after the bulk of the rainfall, the swollen river continued emptying into the quarry. In fact, there were fears that without drastic intervention, the force of the water would finish cutting a new mouth into the white river, which could very well have turned the quarry into a permanent reservoir. How big of a reservoir? Officials estimated that the quarry was nearing a capacity that they estimated at 9 billion gallons. That is Billion, with a B.

With resources from the City of Carmel, Hamilton County, the State of Indiana and the Army Corps of Engineers, helicopters worked with helicopters to drop concrete and sandbags as temporary dams to keep the river within its (engorged) banks. The next problem is what do do with the 9 billion gallons of water. It will have to go back into the river, but it is estimated that the process will take about 90 days.

Of course, it was not sunshine and roses for everyone, because Martin-Marietta took one for the team. Not only do they have to oversee the work of draining the quarry and trying to remove/salvage the machinery at the bottom of this temporary lake, but the quarry (and its workers) are idle when there is a booming demand for their products as communities in the area rebuild.

Why do I find this so interesting? We still got flooding in the Indianapolis area, but nothing close to the severity seen north of us (or in 1913). One measuring station showed a crest of a touch over 21 feet – still about 10 feet above flood stage, but about a foot shy of the old record. That quarry turned out to be an inadvertent safety valve that took 9 billion gallons out of a raging, record-breaking flood and kept a bad situation south of it from being far worse. So, while areas north of the quarry (and Martin Marietta) suffered terribly, areas to the south of it were largely spared the worst by little more than a fluke of luck.

Lede photo from WTHR News, Indianapolis

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