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Officials herald removal of 1933 Dennett Dam for safer river
A decade of planning and $1 million were all it took
Ribbon cutting.jpg
Modesto City Council members, city, county and state officials paddled down the Tuolumne River between Ceres and Modesto Thursday morning to cut a ribbon stretching across where the Dennett Dam was situated for over 80 years and recently removed. - photo by Jeff Benziger

Two rafts carrying Modesto city officials and others took a ceremonial paddle down the Tuolumne River Thursday morning, floating over a spot in the shadow of the Ninth Street Bridge where the Dennett Dam imperiled swimmers and restricted the flow of fish. Councilwoman Jenny Conoyer extended a giant pair of scissors to snip a blue ribbon where the dangerous dam sat up until last summer.

The ribbon cutting celebrated the recent removal of the dam at a cost of $1 million and a decade of planning.

The small dam – originally designed to raise and lower but later seized upward at an awkward slant that created a dangerous undertow – had been in the Tuolumne River for over 85 years. It was dedicated July 4, 1933 to create a 97-acre recreational Lake Modesto on the river near the bridge but was later cursed as an impediment for water craft and fish alike. Heavy river flows in 1940 compromised the dam and was condemned by the state in 1947. Portions of the concrete foundation and metal plates remained in the river and were visible in low-flow summer and fall months.

Work began in early August to dismantle the dam. The lowest bidder came in much lower than the $2.4 million bid obtained in summer of 2017, said Nathan Houx, the city of Modesto’s Parks Planning and Development manager and the administrator of the Tuolumne River Regional Park JPA.

Removing the dam, he said, is “very important to encourage any boating activities” and could help with Ceres’ plans to have a boat launch at Ceres River Bluff Regional Park. It would also remove an impediment to the migration of Fall-run Chinook salmon and Central Valley steelhead. The dam made it difficult for salmon to go upstream to spawn, he noted. With the dam out of the way the fish can now swim to La Grange without major barriers.

Taking out the dam has been an obsession with the Trust. They say the dam made it hard on boaters, kayakers and canoeists, and the swirling undertow it caused may have contributed to three drowning deaths in the past 12 years.

“It was actually a very dangerous dam. It’s killed several people that have been recreating in the river.”
Brittany Gray with the Tuolumne River Trust

“It was actually a very dangerous dam,” said Brittany Gray with the Tuolumne River Trust. “It’s killed several people that have been recreating in the river and so the Trust has been working on taking it out for several years now.”

She said the dam presented “another obstacle” to salmon which migrate annually up the river to spawn. Gray said salmon can only spawn upstream as far as the La Grange Bridge and before the construction of La Grange and Don Pedro dams the ancestral route took fish all the way up into Yosemite National Park for spawning purposes.

“The main victory with this dam is returning this section of the river to its natural flow and making it safer for recreation for the community,” said Gray.

Modesto Mayor Ted Brandvold heralded the achievement, saying the river will be safer for families to enjoy. He said the project is giving him courage to take up canoeing.

“It’ll provide safer boating and a beautiful location for all types of recreation,” said Brandvold.

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Modesto Mayor Ted Brandvold hands Tuolumne River Trust’s Meg Gonzalez a certificate of recognition at Thursday’s ribbon cutting ceremony. - photo by Jeff Benziger

“This is a wonderful project that will improve the safety of the river, remove a barrier to migrating salmon and steelhead, and improve the aesthetics of the river and adjacent Tuolumne River Regional Park,” said Patrick Koepele, executive director for the Tuolumne River Trust. “People will be able to safely paddle downriver creating a fantastic recreational amenity for the community.”

The city of Modesto and Tuolumne River Trust had worked to remove the 1933 structure for nearly a decade, money being the chief obstacle. Many organizations that provided funding for the project had representatives on hand. Funds were provided by the California Department of Fish and Wildlife, the California State Lands Commission, the California Department of Water Resources, the California Natural Resources Agency, the U.S. Fish & Wildlife Service, the Joseph and Vera Long Foundation, the city of Modesto, Stanislaus County and the Stanislaus Community Foundation’s Book of Dreams.

To remove the dam, contractor Innovative Construction Solutions had to build a temporary dam under the bridge and create a temporary channel for the river to flow around the old dam site. Once pieces of the structure were removed and hauled out on the south side, the contractor leveled out the hole below the dam created by water erosion.

Adding to the cost of the project was a litany of environmental regulations dictating how much material can be removed in a day, a survey for pond turtles, construction of a snow fence along the work site to prevent encroachment into adjacent riparian areas, the protection of valley oaks, as well as the replanting of trees and bushes destroyed in the process of moving big equipment in and out.

The removal of the dam improves paddling for those floating downstream from Legion Park. The city of Modesto recently received funding to construct a boat ramp off Neece Drive, creating a “water trail” for those wishing to enjoy the Tuolumne River Regional Park by river. Once completed, there will be 10 river access points and boat launches on the 52-mile stretch between La Grange and the San Joaquin River.

On display at the ceremony were artifacts taken from the dam site, including a metal plate, a 1940s era hubcap and a child’s toy pirate cap gun on a keychain.

The old Dennett Dam as it appeared underneath the old Ninth Street Bridge in 1933.