Diatom samples collected from Kawaikoi Stream differ in species composition and relative abundance from those in Koke'e Stream. Kuwaikoi collects drainage from the Alaka'i Swamp, which developed on a 1200-1500 meter elevation ridge of Mt. Wai'ale'ale extending at a right angle to the NE winds. Kokee lies about 2000 meters further west at about 1100 meters elevation. Frustulia and Eunotia species characteristic of low conductivity waters predominate. Greater diversity of Achnanthes, Navicula, Pinnularia and Surirella taxa occurs in the somewhat more conductive waters of Kokee. The morphological species observed bear a close, but not exact, resemblance to mainland taxa described in the literature. Morphological variations are documented using light and scanning electron microscopy.

Key words: diatom, distribution, Hawai'i, low conductivity, morphology, stream