San Antonio-The NuStar Ammonia Pipeline System will be imposing a 7.5 percent tariff increase, effective July 1, to 70 percent of its ammonia pipeline volumes. The company said that 30 percent of ammonia pipeline volumes have a settlement rate that caps at 3 percent. NuStar is implementing the 7.5 percent increase at its other pipelines and said the increase should positively affect revenues and offset a likely decline in throughputs.