Underwater Pipeline Leak Prevention Act of 1990

Underwater Pipeline Leak Prevention Act of 1990 - Amends the Hazardous Liquid Pipeline Safety Act of 1979 to direct the Secretary of Transportation to promulgate regulations that require operators of underwater pipelines to report on: (1) the condition and safety of such pipelines; and (2) the identification of sections of the pipeline facility which are most likely to cause environmental damage to a sensitive aquatic area. Requires the Secretary to develop model laws (including regulations) for the mapping and survey of underwater pipelines and encourage States to adopt them. Requires States as a condition to receiving Federal grants for pipeline safety programs to have such laws in effect and enforce them.

Requires the Secretary to promulgate regulations relating to the safe operation of underwater pipelines and pipeline facilities operating in sensitive aquatic environments. Requires the Secretary to promulgate regulations requiring all underwater pipelines to accommodate instrumented internal inspection devices (smart pigs).

Directs the Secretary to promulgate regulations to prevent collisions between ships and pipeline facilities located underwater of a depth of 50 feet or less.

Requires the Administrator of the Environmental Protection Agency to study the effects of hydrostatic testing of pipeline facilities.

Directs the Secretary to promulgate regulations establishing standards for the operation and inspection of pipeline facilities that operate at a stress level of 20 percent or less of the specified minimum yield strength of the line pipe.

Requires the Secretary to withhold Federal aid from a State for pipeline safety programs until such State enacts legislation to develop model laws (including regulations) for the mapping and survey of underwater pipelines.