Generally Spots run about 240 feet deep in Washington. They come up at night clear to the shore and can go really deep during the day, The general rule of thumb here is 240 feet deep. I have gotten them as high as 160' and as deep as 390'. If you have a very high powered fishfinder and a fine pixelled screen, you can see them down there. They look like fine cold of puffy locusts or clouds on the bottom. They are really fine specs or dots. I have one of the newer Lowrances with the 8000 watts. You can see them on it. Big water currents are actually way more pronounced then they are. So try ot get good at ready your sonar.
They are generally found on steep rocky banks and can also be found where the slope meets the flat bottom. Down here we have to "power shrimp or prawn" as we get a few days a year and a 4-7 hours on those days. We have to compete with hundreds or thousands of pots in the main areas. There are several areas still in the San Juan Islands that open longer and have really strong currents. I make sure my pots weigh 40 pounds each and have big buoys on them, with a tag line and additional big float. In the San Juans the current will sweep non or low weighted pots away. You have to weight them heavy and the tag line will still float if the main buoy goes under.
Here is our secret to out fish the other hundreds of pots. Use concentrated fish fertilizer on your bait. This stuff is really potent and works great. But don't spill it on you or the boat or you will be sorry. The smell lasts forever. You can also put it in a canister with one 1/4" hole in the top and let the current swirl the scent out slowly. With all of the competition down here you have to be good.Good Luck