Unfortunately, there is an error in the given question. St. Tammany Parish and Davis Landing Road 438 are located in Louisiana, not Wisconsin.

Davis Landing Road 438 is a boat ramp located on the Tchefuncte River in St. Tammany Parish, Louisiana. It is a concrete boat ramp that is approximately 20 feet wide. The ramp provides access to the Tchefuncte River, which leads to Lake Pontchartrain.

According to the Louisiana Department of Wildlife and Fisheries, the Tchefuncte River is open to motorized and non-motorized boats, including bass boats, pontoon boats, kayaks, canoes, and jet skis. However, the department recommends that boaters check local regulations and advisories before launching their craft.

In summary, Davis Landing Road 438 is a concrete boat ramp that provides access to the Tchefuncte River in St. Tammany Parish, Louisiana. It is approximately 20 feet wide and allows for the launching of various types of boats, including motorized and non-motorized craft.