Grow Quest offers this useful account of the Navel orange's introduction to the United States,"In 1873, taking advantage of the North American diplomatic services established in Brazil, technicians specialized in citrus production in Riverside, California, received three seedlings of Bahia orange, from which came the seedlings that would later be spread all over the United States and other parts of the world with the name of Washington Navel. Therefore, the citrus exchange between the two countries is over a century old, and the Bahia orange was a fundamental base for that exchange."
Here's the Rising C Ranch write up on their approach:
We only use "old line" Washington Navel trees combined with sour and sweet orange rootstock. Both rootstocks are out of favor with most growers because of different inherited problems, but no other rootstocks can produce a better tasting piece of fruit.
While the flesh of these oranges is unusually pale, they are intensely flavorful.