The slough was sheltered from the extremes of the tidal bore of the Colorado River and deep enough to prevent stranding on shoals or mud flats at low tide.
[1][2] This made it an ideal anchorage for maritime craft to load and unload their cargo and passengers from the steamboats that took them up and down river without the danger from the tides that they were having to risk in the estuary at Robinson's Landing.
In the month of March 1865, the schooner Isabel, from San Francisco, commanded by W. H. Pierson, found and entered this slough and discharged her cargo, to a steamboat there for the first time.
Subsequently, in June 1865, the Isabel and the brig Laura, unloaded cargoes there again, and the head of the George A. Johnson & Company, George Alonzo Johnson, and his manager Captain Issac Polhamus were there and saw the value of the waterway and named the slough for the Isabel.
However, the plan came to naught, when the Southern Pacific Railroad bought out the company and bridged the Colorado River at Yuma, Arizona in 1877.