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" . --- inflows such that J, 500, 000 acre-feet of flood storage is available on August 1. When inflows are not extremely high or the reservoir is well below flood levels, norma'l releases to meet demands in the Lower Basin are adequate. In years ot high spring runoff. the Corps of Engineers report specifics the minimum average monthly releases to be made for January through June. To determine the minimum release two quantities are calculated. !irst. the maximum rUnoff from the curr~nt month through July is comw pUled as Lake Mea,d natural inflow adjusted for effective storage space in upsl,ream reservoirs excluding Lake ,Powell. Effective storage space is calculated as the .smaller of either the actual space available or the difference between the minimum forecasted inflow and normal releases. 'Ihc minimum forecasted inflow is obtained by reducing the previously forecasted value by 1. 645 times the standard error of estimate for each reservoir. This produces a flow value which can be expected to be exceeded 19 out of 20 times. The second quantity computed is the space in Lake Mead below elevation 1229 (374. 6 meters) plus space in, Lake F-owell below elevation 3700 (1121.8 meters) at the first of each .month. Ihese quantities are calculated as the maximum reservoir capacity rr..inus the previous end.ol-month contents. A function subroutine is called with the above quantities and computes the release as specified by the Corps. In each month of the model calculations from January through July, the criteria above are analyzed to determine th,e operation of the reser- voirs. This operation plan is used in the model either as a required release or a control on the final reservoir contents. When these con- straints are met the basin simulation proceeds. Output Options A variety of output options are available on the river basin simula.- tion model. These are as follows: 156 . OO~J._-'- 1. Forecast Summary. The summarized results of the forecast procedure are shown lor each month a forec,ast is made. Z. Point-to- Point Flows and Salinities. A print is made of main- stream flows and salinities, anq demands on input flows and salinities for every demand and inflow sequence point in every node. This informa- tion can be obtained for a specified month in a specified year, or all months in the year. or all months in all years. 3. Monthly Reservoir Summary. A monthly summary is printed of reservoir operation results for each node including inflow ~o and out- flow from a node. This summary can be obtained for any month or all 12 months. <. 4. Annual Summary. An annual summary and statistics ol flow and flow weighted salinity is printed for key stations in the Colorado River B...sin. Upon completion of a numbe;r:: of runs the annual values at a specific station can be summarized and statistics computed. S. Tape Edit. This option writes the monthly results of an entire run for every sequence point in every node on a disk file. A separate program called TAPEDT extracts information from the disk file and 'puts it in a .{orm specified by the user. Information that can be extracted is: a. Flow and salinity input to the mainstream; b. demands requested and actually diverted; c. consumptive use and shortage criteria,; d. reser- voir operation results and criteria; e. flow and salinity in the rna.in strea.m; and f. powerplant operation results and criteria. The following operations can be done on this information: a. Perform math transformations (add, subtract, multiply, or divide by a constant); b. compute and 'print statistics; and c. compare one parameter against anothe r. ...1 The information extracted and the results of the TAPEDT operations on the information can be output in the following forms: a. Print on highspeed printer; b. punch data cards; and c. plot on microfilm.. Careful consideration of output options and their use is essential since computer costs go up rapidly with increased output. 157 .~ 11