Read time: 5 min.

I was aimlessly weaving through the backroads between Madison and Henry Counties a few years back when I rounded a bend and encountered a concrete spillway. Dams aren’t exactly hidden landmarks, but this one caught me completely off guard! It wasn’t until I started digging into the history of Knightstown Lake in Raysville that I realized what I had stumbled upon on my drive. As it turns out, I’d found Roc Mar Ton Lake just outside Mechanicsburg. Last weekend I went back for some photos from the road. 

Roc Mar Ton Lake Dam is privately owned and impounds Little Creek just west of the Madison-Henry County border. It appears to have been built in 1929¹, but others say the structure was built in 1945²! Unfortunately, finding the dam’s height is an equally dicey proposition:  the Anderson Daily Bulletin said the earthen dam rises eighteen feet³, while a contemporary climate research company says it’s three feet taller⁴. 

Whatever its height, the earthen Roc Mar Ton dam spans 450 feet across Little Creek. At normal pool, the lake impounds about eight acres of water⁵. In the 1950s, the property was known as Stow’s Lake. Then, in the 1960s, it was called County Line Fishing Lake. Day and night, channel cats, bass, crappie, and blue gill could be had for $2.00 a session⁶. 

A name like “County Line Fishing Lake” makes complete sense for a lake located near the county line, but I wondered about its other name, Roc Mar Ton. I found a plat map of Madison County’s Adams Township believed to have been published between 1925 and 1941 to help get my bearings, but the lake hadn’t been dammed yet. What’s more is that none of its property owners featured names that began or ended with Roc, Mar, or Ton⁷! I hope someone chimes in with some further information. 

Both times I’ve passed Roc Mar Ton Lake and its dam, I haven’t noticed any spots to pull over, fish, or enjoy the lake as a visitor. Back in 1956, though, things were a different story! Much of the land was cleared, and it seemed like a popular destination for anglers⁸. Things have changed over the past seventy years- today, a handful of homes and outbuildings sit around the lake, which the assessor calls a farm pond⁹.

Roc Mar Ton Lake might look like the perfect spot for a scenic homestead today, but its dam tells a trickier story. Back in 1977, it met state standards for annual inspections¹⁰, but it was reclassified as a high-hazard structure thirty years later. Officials warned that if the aging dam were to fail, the consequences could be devastating to lives and property¹¹.

Any potential trouble wasn’t apparent to me as I lingered for iPhone photos for a few minutes. Water trickled over and down the dam’s outlet structure much the same as it has for years, I’d guess. Still, the seventy-foot-wide spillway is uncontrolled, without tainter or sluice gates to hold the water in. A maximum of 1600 cubic feet of water per second -12,000 gallons¹²– could flow down the trough if things got dicey! 

Dam failures are rare in Indiana, but they do happen. Just this February, the Blackiston Mill Dam -a weir straddling Floyd and Clark counties- partially collapsed in a washout¹³. In 2008, residents of Princes Lakes in Johnson County evacuated after heavy rains breached the dam¹⁴! In 2015, a report found that at least 85% of Indiana’s aging dams were in deficient condition¹⁵. 

Roc Mar Ton Lake’s dam might be harazardous as well. It may not be a well-known destination today, but its dam is a reminder of Indiana’s hidden infrastructure and the risks that come with it. Even though it’s stood for decades, its classification serves as a warning that even small, rural dams can pose serious threats if neglected.

My roadside discovery led me down an unexpected rabbit hole to piece together fragments of the lake’s history. Yet, questions still remain- especially about its name. Maybe someone out there knows how it came to be called Roc Mar Ton! Until then, the lake will stay in my mental map of curious places as another landmark stumbled upon in the ever-surprising backroads of Indiana.

Sources Cited
1 Roc-Mar-Ton Lake Dam (n.d.). SnoFlo Climate Research and Outdoor Recreation. Web. Retrieved March 29, 2025.
2 de la Bastide, K. (1977, November 28). 145 state dams are potentially dangerous. The Anderson Daily Bulletin. p. 15. 
3 (See footnote 1).
4 (See footnote 1). 
5 (See footnote 2). 
6 Now Open (1969, July 19). The Anderson Herald. p. 11. 
7 Plat Book of Madison County Indiana (n.d.) W. W. Hixson & Co. Rockford, IL. map. Map Collection, Indiana Division, Indiana State Library.
8 Now Open (1969, June 28). The Anderson Herald. p. 13. 
9 Parcel 48-13-14-100-008.000-001 (2025). Office of the Assessor. Madison County [Anderson]. Web. Retrieved March 30, 2025.
10 (See footnote 2). 
11 Kelly, J. (1999, December 26). State dam inspections fall short despite threat of death, damage. The Indianapolis Star. p. 55. 
12 (See footnote 2).
13 Stone, M. (2025, February 3). Blackiston Mill Bridge in New Albany closes after partial dam collapse. See the photos. The Louisville Courier Journal. Web. Retrieved March 30, 2025.
14 Princes Lake dam breached (2008, June 7). WTHR [Indianapolis]. Web. Retrieved March 30, 2025.
15 Kehoe, T. (2015, April 30). Aging Indiana dams prompt concerns of ‘catastrophic collapse’ WISHTV [Indianapolis]. Web. Retriebed March 30, 2025.