The Little Juniata River, often called the Little J, is a 32.1-mile limestone-influenced stream that flows through Blair and Huntingdon counties in Pennsylvania. Originating at the confluence of Spring Run and Kettle Creek near Altoona, it flows northeasterly to Tyrone, then southeasterly until it meets the Frankstown Branch of the Juniata River near Petersburg. Once impaired by poor water quality, significant improvements since the 1970s have transformed it into a premier fishing destination known nationwide for its wild brown trout population and quality insect hatches. The Little J is somewhat unique for Pennsylvania as a limestone spring-influenced river of its size, making it a highly productive fishery for both fly anglers and conventional tackle enthusiasts.