Structure
Bass are structure oriented, and that includes the bottom composition and what hangs above the water. Bass also really like angles, whether that be the angle of the slope on the bottom or the angle of structure and the bank that creates a pocket. When you are determining what structure to fish, I would first look at how much is available and create an overview. Over the years I have created some preferences.
Living over dead (this is for bank vegetation and aquatic vegetation- the green stuff will always have more fish).
Rip rap rules (large human placed rock often used for embankments and dams).
Iso stump will thump (always fish an isolated stump on the bank)
Mucky is yucky (soft bottom void of any rock or wood is generally not your best bet)
Sandy is not randy (a sandy bottom is a sign of a lot of agricultural or construction runoff. It doesn’t usually fish well)
Too many reeds, no need (if the bank is completely lined with reeds, it is tough fishing with a fly rod. I have spent countless hours fishing reeds that resulted in very few fish).
Inlet to win it (all inlets that have inflowing streams, however small, should be fished)
Water clarity and type
During the Spring and Fall water clarity isn’t an issue. But during the summer there can be massive algal blooms. This can start in June and will continue till the rainy season. I haven’t had many “chocolate milk” conditions. I know anglers start to fuss when the water starts to get dingy. Suddenly everybody is a light spectrum analyst and the color debate begins. Fly anglers don’t need to worry about that. Whatever pattern that fishes well when the water is clear, will fish well if the water is off color. The adjustments regarding weight and size could change because of water clarity. When the water is off and the lilies have completely grown in, you can focus on the weedline or dragging a weedless bait over the top.
There are two main types of reservoirs, highland and lowland. The highland reservoirs were dammed in mountainous areas and larger. They have rocky banks and a multitude of long arms that branch off the main lake. In Korea this included reservoirs like, Soyang, Daecheong, Andong, Chungju, and Jangseong. These places don’t typically fully freeze during the winter, and I have seen water as deep as 100 feet when the reservoir is full.
A lowland reservoir typically has a more oblong shape with some distinct coves, but no real arms to speak of. The banks are typically lined with vegetation and the bottom is usually softer. The most distinct feature of a lowland reservoir is the prominent embankment (always a great place to find fish). They also often have one large inflow that functions as an extension of the reservoir (another great place to find fish). Some popular lowland reservoirs are Songam, Sapgyo, Gosam, Asan, and Yesan reservoirs.
Korea has an abundance of small streams and rivers. For flood control purposes every river in Korea has had some kind of manipulation. Bass can be found in every major river of Korea which include the Han, Namhan, Bukhan, Geumgang, and Nakdong. There are countless smaller rivers and streams that flow into these major waterways. Concrete barriers create slow moving sections of the river, which provide good angling opportunities.