The wet, oily substance found mostly embedded in seaweed began turning up Monday scattered along beaches on the west end of Galveston.
General Land Office spokesman Jim Suydam says the source has not been determined. He says no additional tar balls were reported Tuesday and cleanup was nearly complete.
The Galveston County Daily News reports a European shipping company contracted with Phoenix Pollution Control & Environmental Services for the cleanup. State officials say the shipping company did not immediately come forward as possibly being responsible.
The Coast Guard has collected samples for lab tests.
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