Concrete Jetties to Control Erosion of Manitowoc’s Shoreline Were Built in the 1930s and 1940s

The first concrete jetty for Manitowoc shoreline protection was placed in Lake Michigan in 1938. Bob Fay photo.

Ever wonder what the concrete structures in Lake Michigan at the end of Waldo Boulevard and along Maritime Drive are or were used for? They are not old boat docks or fishing piers!

During the 1930s, the shoreline from the foot of State street to Waldo Boulevard and at the outlet of the Little Manitowoc River along Cleveland avenue was being severely eroded during high water levels in Lake Michigan. Wave action was eroding the shoreline and threatening the recently constructed Waldo Boulevard extension from N. Sixth Street to the curve (now roundabout) to Two Rivers. Under an agreement with the state highway department made at the time Waldo Boulevard (part of state highway 42), the city was obligated to provide shoreline protection.

Needing a plan to control erosion, city officials turned to civil engineer Sydney M. Wood of Lake Bluff, Illinois, an expert on protecting lake front property from the erosive action of water on the Great Lakes. Mr. Wood held several patents for beach improvement and jetty design to control soil erosion and protect shoreline property.

Wood’s 1937 patent called for an elongated wall that extended outward from the shore at a right angle. The barrier consisted of spaced upright members and horizontal sections with diamond-shaped apertures, or openings, for stacking. The open design slowed water currents, allowing silt and sand grains to be deposited for ‘making land’ between jetties. The interlocking and stackable sections of the jetty provided stability when placed in the lake.

In May and June 1937, Wood met with the Manitowoc city council to discuss his jetty plan. He suggested the city secure a Works Progress Administration (WPA) grant from the federal government to pay the wages of unemployed men in the city during the Great Depression.

Manitowoc officials successfully applied for a federal grant to build concrete jetties from Waldo Boulevard to State Street, using Mr. Wood’s jetty design for protecting the shoreline and highway. Similar work at Sheboygan and other lake shore cities was successfully protecting the shore from encroachment of the lake.

By the end of December 1937, local men on relief were building forms and pouring Portland cement for sections of a jetty at the lake front between Chicago and St. Clair streets. The WPA project kept men employed during the winter.

In June 1938 a general plan for eight jetties was drawn by city engineer Earl Walter. Four jetties were installed between State and Huron streets. Four others were placed to the north between the mouth of the Little Manitowoc and Waldo Boulevard. The jetties extended 150 to 300 feet into the lake. They were 14 to 16 feet wide and spaced 250 to 500 or 600 feet apart.

In September 1938, work began placing the first jetty in the lake at the foot of State Street, 750 feet north of the harbor breakwater. Seventy men worked in four shifts. The work went on for 12 hours each day, including Sundays. About 1,000 barrels of cement were used to construct the jetty.

Concrete piles, 12 feet long × 1 foot square, and horizontal sections, 22 feet long × 3 feet wide, were lifted and placed in the lake using a crane and marine equipment leased by the city from the McMullen and Pitz company. The first jetty cost $5,588.

Sydney M. Wood’s 1937 patent design for a jetty consisted of concrete structural elements to control erosion along the Manitowoc shoreline from State street to Waldo Boulevard. Bob Fay photo.

The jetty building program continued in 1939-1940 and again in 1943-1946. By July 1943, high lake levels and waves had caused several cave-ins, toppling part of an iron sewer pipe and washing out part of Cleveland avenue near the Little Manitowoc River bridge. The city responded, at Mr. Wood’s recommendation, by placing a concrete jetty, 1300 feet long, parallel to the shore to control erosion.

While the jetties provided some shoreline protection and made some land, they could not control high lake levels and the continuing damage from soil erosion. During the 1950s, the city of Manitowoc needed to place broken concrete paving and sidewalks as well as hundreds of tons of earth and rock fill along the eroded shoreline from the Little Manitowoc River to Waldo Boulevard.

Efforts to control erosion along the lake shore continue. In 2022, a Central Brown County Water Authority emergency shoreline stabilization project was conducted along Maritime Drive and at the foot of Waldo Boulevard. Record high lake levels caused severe soil erosion along 330 feet of the shoreline, endangering the CBCWA’s water transmission main from Manitowoc to the Green Bay metro area. During revetment work by Mammoth Construction, the shoreline was regraded for the placement of a crushed limestone base and large stone boulders.

Time will tell if these measures halt further erosion of the shoreline and control the damaging effects of fluctuating lake levels and waves on Lake Michigan.