CHANNEL MODIFICATIONS OF HAWAIIAN STREAMS

In their 1978 report, Timbol and Maciolek identified channel modification as a significant factor contributing to the degradation of stream biological quality in the Hawaiian Islands Six types of channel modifications were distinguished.

Timbol and Maciolek wrote, "Continued channel modification in Hawaii is certain, as evidenced by current channelization proposals for Kohoma and Iao streams on Maui and Makaha stream on Oahu. Presently on Oahu, a dam is being constructed across Kamooalii tributary of Kaneohe Stream. Environmental commentary is difficult because of the lack of definitive information on the effects of channelization either on total stream ecology or on individual native species. Past commentaries have been based on generalized information (mainland U.S. and limited ecological data on Hawaiian streams) and a few specific observations on local channelization effects. Concrete-lined flat-bottomed channels obviously provide no habitat for native fishes or crustaceans, and expose water to excessive insolation. The effects of such lined channels on the quality and quantity of fauna upstream (i.e., effects on migration) or on the downstream environment (e.g., heating) are unknown. Such are examples of the principal informational needs today."

"This report concerns that portion of the project involving a one-year (August 1975 - September 1976) statewide, exhaustive inventory of perennial streams with channel modifications, including a general survey of habitat factors and macrofauna. It includes the islands of Kauai, Oahu, Molokai, Maui, and Hawaii. Niihau and Lanai, the remaining two inhabited islands in the State, were not surveyed. Niihau is small, relatively arid, and under private ownership that prohibits entry of non-residents. Lanai apparently has only one stream, and it is located in an area of difficult access. It is assumed that this lone stream is not channelized.

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