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CRDSS <br />TASK MEMORANDUM 1.15-4 <br />Water Rights Planning Model <br />Evaluation of U.S. Bureau of Reclamation Model HYDROSS <br />1.0 ISSUE <br />The purpose of this memorandum is to generally describe the computer model HYDROSS and to <br />address its suitability for incorporation into the CRDSS. The evaluation of the model's functionality <br />with respect to the intended goals and objectives of the CRDSS was conducted based on a review of <br />the model structure and utilization of the Level One and Level Two decision criteria described in <br />Task Memorandum 1.15-2. <br />2.0 DISCUSSION/ANALYSIS <br />Background Information <br />The Hyd rologic R iver O peration S tudy S ystem, HYDROSS, is a system of computer programs for <br />use in conducting monthly water supply studies and is considered a hydrologic accounting model. <br />HYDROSS was originally developed by the U. S. Bureau of Reclamation (USBR) in 1977. The <br />model has continually been upgraded and enhanced and is now available in both PC (DOS) and <br />workstation (UNIX) environments. The model was developed to assist in planning studies for <br />evaluating existing and proposed demands on a river system. It is designed to operate over a selected <br />period of record, simulating the effects of existing and proposed water rights and projects on the <br />historical pristine "natural" flows. The model operates on a monthly time-step. <br />It is the current USBR policy to readily distribute executable PC versions of the code for HYDROSS. <br />For the workstation version, there is a one-time license fee ($3,500), and continued updates and <br />support for the workstation version are available for an annual cost of $3,000. The USBR has <br />verbally indicated that should HYDROSS be selected as the core model for water rights planning in <br />the CRDSS, it may be possible for the State of Colorado to obtain unrestricted use of the source <br />code, pursuant to some form of license agreement that would indemnify the USBR in the event the <br />code were altered in a manner that could potentially result in erroneous solutions. <br />The HYDROSS model is widely used by federal agencies including the USBR and the U.S. Fish & <br />Wildlife Service (FWS) for simulation of small-scale and large-scale water resource planning <br />activities. Because of its current and expected future use by federal agencies and because of the <br />anticipated high level of support and maintenance, HYDROSS is considered a viable candidate for <br />incorporation into the CRDSS. <br />Basic Description of Model Operation and Function <br />HYDROSS is written in FORTRAN V and, as stated above, is available either in a PC or workstation <br />environment. HYDROSS requires a data set of pristine or "virgin" stream flows which represent the <br />historic stream conditions, absent the effects of any man-related activity. This data set is not <br />generated by the model but must be developed separate from and outside of the model using historic <br />1 <br />A275 05.10.94 1.15-4 Fosha, Hyre <br />