‘It’s important to get the mill running again’: Group works to restart Peirce Mill’s milling operations after an August breakdown

The 2026 milling season at Peirce Mill in Rock Creek Park typically begins in April. But this month, the grinding stones remain idled while devices critical to the mill’s operation are in the shop.

Two water recirculating pumps were installed during the major restoration project that allowed the historic mill to reopen to the public in 2011, after a 17-year shutdown.

Last August, both pumps broke down. And on April 1, after months of fundraising, planning and more cooperative weather, Friends of Peirce Mill had the pumps removed and sent to STH, Inc. in Frederick, Maryland, to determine whether the pumps can be repaired or must be replaced.

We asked the group’s executive director, Angela Kramer, to fill us in on the efforts to get the mill running again.

Friends of Peirce Mill Executive Director Angela Kramer.

Forest Hills Connection: Describe what happened the day the recirculating pumps failed.

Angela Kramer: On August 2, we started the mill for our regular milling demonstration. The Friends of Peirce Mill and Rock Creek Park normally offer milling demonstrations one weekend a month from April to October. Around 10:45 a.m., miller Cece Michalowski noticed a burning smell coming from the pump control panel on the first floor of the mill.

Cece immediately shut down the mill. I called 911 and we evacuated the building. The fire department inspected the control panel and made sure everything was safe. Because the pumps had malfunctioned, we could no longer run the mill.

Peirce Mill’s idled grindstones.

Explain how the pumps are supposed to work.

Rock Creek has changed since the mill was built in 1829, so we can no longer use creek water to power the mill.

Instead, we use two underground recirculating pumps to raise water high enough inside the flume to turn the water wheel. The waterwheel turns the gears, and the gears turn the millstone, which grinds the corn.

This illustration shows how deep the water in the flume must be to turn the waterwheel.

Do you have an estimated timeline for getting the pumps back up and running?

We’re working to get the mill running again as soon as possible, but it’s a complicated job that will take at least a few months to complete.

What is the estimated cost of repairs? And how is it being covered?

This project is estimated to cost more than $150,000. This includes repairing or replacing the two recirculating pumps and hiring a vac truck to clean out the mill’s water system (the headrace, flume, wheel pit, and tailrace).

Thanks to our generous donors, the Friends have raised more than $100,000 to fix the recirculating pumps. We’re looking for additional funding to get the mill running again.

Workers removed the recirculating pumps on April 1.

Why is it important to get the mill up and running again?

From an engineering perspective, it’s important to get the mill running again because the waterwheel and wooden gears need regular turning to stay in good condition. Like any machine, the mill needs to run. It’s especially hard for the waterwheel to sit in water.

But getting the mill running again is also important to our visitors, who really want to see Peirce Mill in action! If you’ve visited on a milling day, you know how excited folks are to watch us grind corn.

A Peirce Mill grinding stone before the miller sets it in motion. (2014 photo)

Peirce Mill is also a great resource for STEM education, because kids can see how the waterwheel turns the gears. We believe a 19th century gristmill can inspire the next generation of engineers.

What are some of the other challenges of restoring and operating a 19th century mill in the 21st century?

One of the biggest challenges is keeping people trained to operate and maintain the mill. The Friends are active members of the Society for the Preservation of Old Mills (SPOOM) Mid-Atlantic Chapter. We visit other mills around the region and organize miller trainings to share knowledge.

The Friends and Rock Creek Park also work closely with millwright Gus Kiorpes, who inspects the mill annually and makes any urgent repairs. Unfortunately, there are only a few millwrights left on the East Coast.

What’s on the mill’s to-do and wish lists after the recirculating pumps are repaired?

As Peirce Mill approaches its Bicentennial in 2029, the Friends are partnering with the National Park Service to keep Washington’s last working grist mill running into its third century. There are lots of items on our to-do/wish list!

But we have one upcoming project related to maintaining the waterwheel and tailrace. FOPM has been working with Rock Creek Park to design an automated system that removes water from the tailrace, preventing the waterwheel from sitting in water. We currently use pumps and hoses to do this job, so the new system would save us a lot of work!

The waterwheel and the tailrace. The blue hose is part of the makeshift system volunteers use to pump water out of the tailrace.

Visiting Peirce Mill: The mill is open for tours Saturdays and Sundays from 10 a.m. to 4 p.m., and often hosts free events. Upcoming events include the “Herring Heroes” obstacle course in honor of the herring’s upstream Rock Creek journey each spring, and the mill’s first Historic Trades Festival on May 16.