INTRODUCTION The Offshore and Coastal Dispersion (OCD) model (Version 3.0) was developed in 1985 by Environmental Research and Technology@ Inc. (now ENSR Corporation) (Hanna et al.@ 1985) under contract to the U. S. Minerals Management Service (MMS). The model was revised in 1988 by Sigma Research corporation (Hanna and DiCristofaro@ 1988) under contract to the American Petroleum Institute (API). Further modifications have recently been made (Version 4.0) by Sigma Research (DiCristofaro and Hanna@ 1989) under contract to MMS. The three model versions referred to above are hereinafter referred to as OCD3.0@ OCDAPI@ and OCD4.0@ respectively. Reese-Chambers Systems Consultants@ Inc. was retained by API to review the three model versions. This review involved identifying changes in the code and user's manuals@ evaluating the technical soundness of the identified changes@ creating a hypothetical test matrix for evaluating the models and running the models on the test matrix. The purpose of this report is to document that review. Section 2 provides a complete description of Reese-Chambers' review of the user's manuals for all three model versions including identification of changes to the models@ technical soundness of the changes@ and recommendations. Section 3 describes the hypothetical test matrix created to evaluate the models and provides an analysis of model results based on that matrix. Section 4 reviews model evaluations and Section 5 includes a summary of review findings and recommendations. Finally@ Section 6 provides conclusions of the review.