When someone asks "where can you catch trout?" the answer can come in two forms: they can be asking what streams are good for catching trout or where in the streams trout might be hiding. In this article, I'll answer both questions - first regarding the broader question of how to find a trout stream and then I'll help you figure out where you need to cast for the best likelihood of catching a trout.
Not every stream is good stream to catch trout. Due to the popularity of trout fishing, your best bet is to find one that is stocked regularly with fish from hatcheries. There are many streams where only a "wild" population of trout live (that is, where there are no stocked trout), but usually these streams have limitations on fishing (a short season, catch-and-release only policy or fly-fishing only) and they are almost always less productive than a stream that is regularly stocked.
In Central Pennsylvania there are two creeks that run fairly near each other - the Yellow Breeches Creek and the Conodoguinet Creek. The Conodoguinet is larger and provides habitat for smallmouth bass, tiger musky and a variety of panfish, and it does have trout, but it is not regularly stocked. The Yellow Breeches on the other hand, is smaller and contains smallmouth bass and panfish, but is also well-stocked with trout from both the Yellow Breeches Angers & Conservation Association and the Pennsylvania Fish and Boat Commission. Once in a while you do catch trout in the Conodoguinet, but it is usually more about luck and someone fishing for whatever might bite that day. On the Yellow Breeches it's much more common to catch 3, 4 or even your daily limit of 5 in a few hours.
How do you know which streams are regularly stocked? One way is to check your state's commission that regulates fishing (in Pennsylvania it is the PFBC, in other states it may be the Department of Environmental Conservation or the Game Commission) and see which streams are being stocked. If you can't find that, look at what streams have special regulations - an extended season or different size or creel limits - this will often indicate a hearty trout population.
If this fails, the best thing to do is to drive to the local creeks on the opening day of trout season and see where people are fishing. Just like a restaurant - if it's busy it must be good! This may actually be a better indicator than monitoring stocking schedules!
Okay, now you've found a location, now where in the stream are you going to find trout? It could be very wide and there might be just a few spots where the trout are hanging out.
If the creek isn't crowded with other fishermen and there is room to do this, the first thing I do is take a few casts from about ten feet back from the bank. This is an area where you should be out of sight from the fish and you'll be able to reach any that are mingling around the near bank. I don't usually catch any on these casts, but sometimes you get lucky!
Once I'm in the water (I always fish with waders) I aim my casts towards three things - the bank, large objects in the water and holes. And if I can find a combination of the two, even better!
I like to cast as close to the bank as possible without hitting the other side. And I do hit the other side often - which isn't a problem unless there's a bush or low-hanging leafy branch there. Fish will hang out in holes along the bank and will dart out to hit a lure going past. This area keeps them safe from predators and hidden from prey.
Large Objects in the Water
The downstream side of a fallen tree or big rock in the water will have an area where the current isn't as hard, giving fish an area to sit and possibly wait for a meal to drift by. The upstream side of an object also has an area where the current is calmer and can be a collecting area for debris and insects that trout might feed on. I try to cast as near to these objects as possible - without hitting any branches that my lure might snag on!
Just like a large object in the water, a hole is an area where the current slows and debris (i.e. trout food) settles. The best holes are 2-6 feet deep, depending on how deep the fast-flowing area is - if the water was flowing fast in 2 feet of water, a 4-foot deep hole would likely hold fish. Beware of holes that are over 8 feet deep. They may hold trout near the bottom, but you will need to get your spinner down deep enough.
One of the reason I like Panther Martin lures, is that they will run deeper than a Mepps Aglia or Rooster Tail spinner. (Mepps also makes a spinner similar to Panther Martin called the Mepps XD which works well in holes.) Rather than disturb a school that might be hiding in the hole, I'll start by casting around the edges of the hole and working my way towards the center. This way the school won't be extra wary due to a fish being hooked and thrashing in the midst of it's companions.
Bank/Hole or Object/Hole Combinations
When there is a hole along the bank, instead of aiming directly for the bank, I'll creep up on it. Just like when fishing a hole, I want to work my way in slowly and casting to the bank usually means going across the hole and risking disturbing the school.
When there is a large object on the edge of a hole, I'll do the opposite - first cast towards the object, then work the hole. There's just a very good chance that fish will be congregating around that object so I'll go there first.
One more thing about cast selection: don't waste your time on visible fish. If you can see a fish in the water it is likely either a trout that has been spooked and not prone to strike or a less desirable species like a sucker or chubb. Go ahead and take a couple casts, but don't chase it all over the creek - you'll likely just find yourself wasting time that could have been spent working a well-populated hole.