This report summarizes records of streamflow and water temperature collected prior to October 1, 1975, in the Cook Inlet Basin of south-central Alaska. Streamflow records for gaging stations are tabulated as monthly and annual summaries and annual extremes. For those gaging stations at which continuous or daily water temperature records have been collected, monthly summaries of water temperature extremes are shown. For other gaging stations periodic water temperatures are published. Discharge at crest-stage partial-record stations and at miscellaneous sites is tabulated. Results of seepage investigations are presented for 4 streams.