Last Mississippi River Gage Reader Reflects On River History

On June 29, a quiet ceremony marked the end of an era as Art Denkmann, 81, the last manual Mississippi River gage-reader, was presented with a certificate of appreciation by the St. Louis Engineer District’s water control team for 56 years of faithful service.

“We became dinosaurs,” Denkmann told The Waterways Journal. “I was the last one that did a visual verification on a daily basis.” The manual gage readers are being replaced by the electronic data collection platform (DCP) system. This system can provide a reading every 15 minutes and the data will be sent via satellite telemetry, with the numbers updated online. The system began to be installed in the 1990s.

Not that the physical gage is being removed. The river gage Denkmann was responsible for is still embedded in the cobblestones at the foot of Market Street in downtown St. Louis. It has been in place since March of 1933, when the Corps of Engineers took responsibility for reading the gages away from the St. Louis harbormaster, whom Denkmann remembers watching as a kid. “I used to watch him on a catwalk posting these numbers. I didn’t know what he was doing, and I never dreamed I would be taking over that job years later.”

Throughout the years tourists, locals, and navigation interests have passed by this riverfront gage, measured in tenths of a foot.  It still has the welded hash marks that were added in 1968 after the gage was found to be off by a few tenths. “Today’s gage is a replacement down to the 10-foot mark,” said Denkmann.

The highest reading he ever recorded was 49 feet, 8 inches during the flood of 1993. The lowest was -3.4 feet during a freezing winter in the 1980s.

Denkmann was one of a number of volunteer readers monitoring 129 river gages in the region, not just on the Mississippi River but on the Missouri and Illinois rivers as well, since parts of both are included in the St. Louis Engineer District’s area of responsibility. His wife read the gage below the Jefferson Barracks bridge. The gage readers were given a stipend to cover expenses. “That just about covered my gas,” chuckled Denkmann, who also worked in general contracting while raising two kids.

He figures it took about three hours each morning to drive to and from the riverfront and take the readings. “I used to carry laminated, waterproofed business cards with my title on them, in case they got waterlogged,” he said.

Denkmann’s association with the river goes way back. His father, Art Denkmann Sr., operated the Mississippi Belle excursion boat from 1961 through 1976. Before that, said Art, his dad practically raised him aboard a Chris Craft cruiser in the Alton (Ill.) Pool. Art Sr. grew up in south St. Louis in an area where bluffs overlook the river, said Denkmann. It was close to where two Corps of Engineer snagboats, the Wright and Macomb, were moored. “My dad said he learned to swim off the backs of those two boats,” said Denkmann.

Art Sr. bought the Mississippi Belle after he sold the Chris Craft. Denkmann helped his dad with the Mississippi Belle, earning his pilot’s license in 1965. Since he was on the riverfront every day anyway, he was a natural candidate to read the gage, when the previous gage reader moved to Colorado.

Many milestones have passed on the Mississippi River during Denkmann’s career as a gage reader such as droughts, the opening of Melvin Price Locks and Dam, the great flood of 1993 and the 2019 flood, along with many enhancements to the St. Louis riverfront. He remembers many fluctuations in river stages and recalled that communication between the upstream and downstream gage readers was difficult. The new DCP system will enhance the gage reading process even more.

River gage readings are posted on the River and Reservoir Report found on the St. Louis District’s website that is referenced by those who boat or work on the river. Biologists use the data to assess fish habitat, and river forecasters use the data readings to estimate how bad floods may get.

“The Corps of Engineers monitors 129 gages daily in the region. A centennial gage like the St. Louis gage has been invaluable when formulating flood watches and warnings and producing river stage forecasts,” Joan Stemler, St. Louis District water control chief, said. Data from the St. Louis gage is used to analyze long-term trends including the impact of climate change, urban growth, and estimating how much water seeps into the ground joining the Mississippi River watershed that drains 31 states and two Canadian provinces.

Denkmann has many memories of the changes to the river industry in St. Louis. He remembers Federal Barge Lines and the concrete barges that helped transport vital war materials down the river during World War II. “I was sorry to see St. Louis Shipbuilding go by the wayside,” he said.

“I’m grateful I’ve had the opportunity to do all these things,” he said. But all things come to an end. “My kudos go out to the Corps because of their employment of more technology. They never stop improving!”