Historic, tragic Dennett Dam removed as part of plan to restore river in Modesto

Fireworks, a Venetian boat parade, California Gov. James Rolph and more than 20,000 people were part of a July 4, 1933, dedication ceremony for Dennett Dam, which was intended to create serene Lake Modesto along the Tuolumne River.

There was significantly less pomp and circumstance this week when crews removed the tiny dam from the river, where it had become a dangerous hazard and an eyesore near Modesto’s Ninth Street Bridge.

Those behind the project envision that removing the dam will restore the natural habitat and change the public’s perception of that area along the river.

“We want to get people on the river, and we haven’t been able to do that,” said Nathan Houx, Modesto parks planning and development manager. “I don’t know if a lot of people know there’s a river there.”

Work on the removal of the dam’s remnants began earlier this month. The roughly $1.6 million project is a partnership between the city and the Tuolumne River Trust.

The water flowing over the dam can create a whirlpool that pulls swimmers down into a hole created by the falling water, Trust Executive Director Patrick Koepele has said. His group has been working on removing the dam since 2010.

The project will return that section of the river to its natural state and provide salmon and steelhead with unimpeded access to 37 miles of upstream habitat.

Canoeists and kayakers also will have an easier and more enjoyable time. Houx said a $780,000 grant from the state Division of Boating and Waterways will fund the construction of a boat ramp along Neece Drive, just north of the driving range at the Modesto Municipal Golf Course.

The upstream boat ramp could serve as an exit. Houx said construction of the ramp could begin in 2020.

A $500,000 grant from the state Department of Parks and Recreation will fund the construction of a 100-seat outdoor theater at Legion Park. Houx said the theater will be a venue for nature education for students, including those at nearby Orville Wright Elementary School.

There are also plans for trails at Tuolumne River Regional Park. These are all projects, along with the removal of Dennett Dam, to provide an environment inviting for boaters, children, hikers and swimmers.

“The more people down there doing good things, the less people down there doing bad things,” Houx said. “We want (the river) to be an asset to the community.”

These areas along the river in Modesto have gained a bad reputation for garbage dumping, drug use and other criminal activity. The areas also have become a refuge for homeless people who camp in the parks along the river.

Eighty-eight years ago, city planners had loftier goals of creating a 97-acre water and recreation resort with the installation of Dennett Dam. It was supposed to create a “pleasure lake,” according to a 1933 article from the Modesto News-Herald. The dam was dedicated along with the three-lane Ninth Street Golden State Highway Bridge.

At a cost of nearly $10,000, construction of the dam created Lake Modesto along Legion Park. The dam increased the river depth to 10 feet to provide quiet water navigation as far upstream as Empire Bridge.

It originally was called Lake Modesto Dam, but was renamed for former Mayor L.L. Dennett. The dam’s foundation was planted 20 feet below the river bottom.

Just a year after the dedication ceremony, Lake Modesto and Legion Park were the centers for a Fourth of July celebration that included about 30,000 people. There were canoe and kayak races, along with a motorboat-water polo game and an event where swimmers were given the chance to keep the duck they caught in the water.

The dam washed out in 1935 and again in the early 1940s. It was condemned in 1947. Only its foundation was left, spanning the Tuolumne River under the bridge.

In the ‘30s and ‘40s, Dennett Dam served as a watering hole for the public during the warm summer months. Plans to rebuild the dam were revived but eventually died.

In 1970, there was a plan for two Tuolumne River dams. The dams would be part of the then proposed Tuolumne River Regional Park, creating a large enough lake to attract boating concessions, boathouses and river recreation.

Decades later, the dam impeded fish and deterred people who canoed and kayaked along the river. It has been the site of three drownings since 2006. When the river ran low, the remnants of the dam’s foundation were visible, creating a roughly 2-foot drop.

Work associated with the dam’s removal is expected to continue until late September, possibly October. Houx said crews will fill in the hole created by the dam with sediment that had been blocked by the dam.

There’s also a lot of debris to remove. Innovative Construction Solutions, which was hired as the general contractor, temporarily diverted the river around the dam through a channel near the river. The water diversion is expected to continue for another few weeks.

ICS also will remove the depression in the riverbed created by the water flowing over the dam and remove all traces that this had been the site of a major construction project.

This story was originally published August 22, 2018 at 2:25 PM.