DUBUQUE HARBOR IMPROVEMENT COMPANY
The Mobley proposal, which was substantially accepted, planned to fill up Seventh street extension and bridge the sloughs with double track bridges in three months or fifteen months at the most; fill up Seventh street forty feet on top in twenty months; build a levee 320 feet long and sixty-four feet wide.
Consideration was to be a strip of ground one block wide out to the river on one side of Seventh street extended, blocks to be 206 feet deep, as soon as the work was half done; also alternate blocks on the other side; also the right to use the dredge boat for three years.
In April, 1856, the Harbor Improvement Company asked permission to extend Fifth street to the river. Many warehouses were going up along the levee and along Seventh and Jones streets. Eighth Street extended was the northern boundary of the Harbor Improvement Company's tract.
The work done by them had lasting value, but the officers decided to discontinue active operations when a financial panic struck the city around 1857.
The Dubuque City Directory of 1857-1858 listed as officers of the company: Lucius Hart Langworthy, President; Samuel Duncan, Secretary; Ed. A. Lull, Treasurer.
Oldt, Franklin T., History of Dubuque County. http://www.ebooksread.com/authors-eng/franklin-t-oldt/history-of-dubuque-county-iowa-being-a-general-survey-of-dubuque-county-histor-tdl/page-12-history-of-dubuque-county-iowa-being-a-general-survey-of-dubuque-county-histor-tdl.shtml
Dubuque City Directory, 1857-1858