He may have stocked the stream (legally or illegally) though I cannot imagine a legit fish hatchery from any state risking a huge fine for stocking without a permit. While the land around the stream can be owned the stream bed is not. Restrictions apply. Even if he did....
There are no "native" trout to Piru Creek unless they are descendants of Southern Steelhead which they are trying to bring back. So many trout from Piru have swam upstream from Piru Lake and also were stocked by the tens of thousands in Piru Creek for decades at Frenchmans Flat miles ABOVE Piru Lake..So...as I posted earlier because Piru Creek flows into a river (Santa Clara..which also was stocked with trout decades ago) that flows into the Pacific Ocean no trout stocking is allowed in those waters. Throw in a toad and frog..No trout. .But again the main reason is the Southern Steelhead
Some info
http://caltrout.org/regions/southern...ation-gallery/
Piru Creek - River
California
Piru Creek is a major stream, about 71 miles long, in northern Los Angeles County and eastern Ventura County, California. It is a tributary of the Santa Clara River, the largest stream system in Southern California that is still relatively natural.
Length: 71 mi
Mouth: Santa Clara River