McHenry’s Mill Dam

When McHenry was first being settled, the largest business in town was the Owen Brothers Mill. Established in 1851, the brothers ran their business until they sold it to Richard Bishop in 1872. The Owens ran a grist mill that used the power of a water wheel to grind wheat and other grains. In order to get the power needed to turn the mill wheel at a rapid rate, the Owens build a flume. A flume is constructed when a flowing body of water, in this case, Boone Creek, is dammed. The flume was then dug out, usually following a more narrow path parallel to the original creek. The water that has been backed up is now channeled down the newly dug-out area, providing a concentrated, more powerful flow of water. After it’s done powering the mill wheel, it then flows into what is called a mill race, which drained into Boone Creek.

Image of the Owen mill from the 1862 McHenry County Plat map.

The Owens had an impressive structure for their mill, constructed in 1851. At five stories, it was easily the tallest building in town. It stood where the Green Street Cafe is located today. The mill provided a huge service to local farmers. Before the mill was constructed, grain had to be taken to Waukegan to be processed. Given the poor condition of the roads at the time, taking grain out of town was a huge inconvenience. The Owens ran the business until 1874 when they sold it to Richard Bishop. Stephen Reynolds purchased it in 1901 after renting it from Richard Bishop for a few years.

Taken from the 1872 McHenry County Plat Map. Note the mill in the upper left-hand corner.

The dam was originally constructed mostly with large glacial stones found in the area. Hand tools were used as well as stone boats. Since the rocks were too heavy to put onto carts, large rocks could be pushed or rolled onto the stone boats. (Stone boats are sled-like devices that large items could be placed upon and then pulled by animal or human power.) While the mill was great for local businesses, it did have some drawbacks, namely flooding.

Picture part of the McHenry Public Library collection.

Three particularly bad floods stood out in 1875, 1887, and 1898. In September 1875, there was a torrential rainstorm in the area. According to the Plaindealer, had the Owen’s mill not been so well built, it would surely have been completely destroyed. The bridges that spanned over the mill race and Boone Creek on Green Street both needed to be replaced. Quick work by the Owens helped save their mill and the dam. It was also noted the east side of Green Street resembled a small lake for some time. There was some damage to the dam, resulting in Richard Bishop having to fix the structure. He used a pile driver method powered by horses, lifting up a heavy stone and dropping it to pack down dirt and rock. Large glacial rocks used in the construction were picked up from the location where the McHenry Country Club now sits.

Later in February 1887, melting snow and heavy rain caused horrible flood waters that overwhelmed the dam and Richard Bishop’s mill and pickle factory. Flood waters threw barrels full of pickles through the south wall of the factory and ended up in the mill race. The southside foundation for the factory was also washed out and repairs took about a month to complete.

Photo of the Mill Race Dam from 1910. Compare this photo with the one above.

The June 1898 flood was the worst of the three. Brought about by some of the worst rain in memory that raised Boone Creek to an unprecedented level. Both bridges were nearly destroyed, with the one over the mill race barely standing. Also, both of the town’s mills, the Bishop and the Hanley, were completely flooded out. The Bishop mill was picked up off of its foundation and pushed almost onto Green Street. The flood was so intense that when the dam gave way, the water washed the opening to twice the structure’s normal size. Like the flood in 1878, the Bishop mill was unable to grind grain until repairs were made, which took about a month. It was estimated that the Bishop estate had about $2000 and the Hanley mill $1000 in damages.

1898 Sanborn map from July 1898, one month after the flood took place.

The mill fell out of use and was torn down in 1912. Even with the old mill gone, the mill race was retained as much of the area’s sewers and drainage pipes went into the race. The dam was taken down in 1929 to make way for a new subdivision. More on that in next month’s blog post!


  • “George Owen, 80, McHenry Navtive; Dies In Elgin.” The McHenry Plaindealer. (McHenry, IL) 25 Jun 1936, 1. Web. 20 Aug 2022.
  • “The Big Storm.” The McHenry Plaindealer. (McHenry, IL) 15 Sep1875, 1. Web. 20 Aug 2022.
  • “The Great Thaw.” The McHenry Plaindealer. (McHenry, IL) 9 Feb 1887, 5. Web. 20 Aug 2022.
  • “The Big Storm.” The McHenry Plaindealer. (McHenry, IL) 29 Jun 1898, 1. Web. 20 Aug 2022.
  • “Attempts To Build Dams.” The McHenry Plaindealer. (McHenry, IL) 17 Oct 1935, 6. Web. 20 Aug 2022.
  • “The Mill and Pond.” The McHenry Plaindealer. (McHenry, IL) 28 Nov 1935, 6. Web. 20 Aug 2022.