The Obama administration asked a federal appeals court Tuesday to reinstate a moratorium on deepwater petroleum drilling, saying it is needed to reduce the chance of a second spill similar to the one now spewing crude into the Gulf of Mexico.

The fallout from that spill, the result of an April 20 explosion on a drilling rig leased by BP PLC, was evident in the Gulf region Tuesday, as tar balls lapped onto the Texas coast and oil was sighted in New Orleans's Lake Pontchartrain.

The...