Ku Tree Reservoir Fishing Guides

About the Ku Tree Reservoir

Ku Tree Reservoir sits in the foothills of the Koolau Range above Wahiawa on the central plateau of Oahu, one of a network of small impoundments built to store irrigation water for the sugar and pineapple plantations that dominated this landscape for most of the twentieth century. The plantations are long closed, but the reservoirs remain, fed by high rainfall on the windward slopes above and held by earth dams across the gulches. They now form the great majority of Hawaii’s standing freshwater.

Hawaii has essentially no native freshwater sport fish. The islands’ native stream fauna consists of gobies and other small amphidromous species adapted to short steep streams, and every freshwater game fish an angler can catch here was introduced, most of it during the plantation era and the decades after. That history gives reservoirs like this one a fishery assembled entirely from mainland and tropical imports, which is unusual enough that it is worth understanding before fishing here.

The gauge reports reservoir stage, and stage is worth watching because these small impoundments respond quickly to the heavy rainfall the Koolau slopes receive. Largemouth bass are the principal target and the reason most anglers come, with smallmouth bass present in parts of the Wahiawa system, channel catfish reaching good size, and tilapia, bluegill and carp abundant throughout. Access to the plantation reservoirs varies and some require permission, so confirming the current arrangement before travelling matters more here than on most waters. Wahiawa Reservoir nearby is the better known and more accessible water of the group, and most visiting anglers start there before working outward into the smaller impoundments. Fishing here is a year round proposition because there is no cold season to shut it down, and the practical constraint is rainfall rather than temperature. A run of heavy windward storms will push the reservoir up and colour it within hours, while a dry spell leaves it low, clear and difficult in the middle of the day. Reading the stage record before travelling is the single most useful piece of preparation an angler can do on this water.

Access

Wahiawa - the town below on the central plateau, with services, lodging and the nearest tackle.
Wahiawa Reservoir - the larger and better known impoundment nearby, also called Lake Wilson.
Koolau Range - the windward mountains above, the source of the rainfall filling these reservoirs.
Haleiwa - the North Shore town down the plateau, with services and the harbour.
Schofield Barracks - the military installation adjacent, which constrains access in parts of the area.
Honolulu - forty minutes south, with the international airport, tackle shops and full services.
Kaiaka Bay - the receiving bay on the North Shore, with saltwater access and a boat ramp.

Seasons

Spring: warm and rising with trade wind rainfall, with bass spawning and the most active fishing of the year.
Summer: hot, stable and low rainfall, with bass fishing best at first light and tilapia everywhere.
Fall: still warm with rainfall increasing, and consistent bass and catfish fishing throughout.
Winter: the wet season, with heavy Koolau rainfall raising stage quickly and the fishing dictated by how much water has come through.