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0013G6 ,t -2- Present Operating Conditions Apparently it was originally intended to supply irrigation water at the rate of one second-foot for 70 acres, but years of experience show that the rate of actual use is greater than this. Until quite recently the Orchard kesa District irrigated not more than 7,500 acres and the pumpin plant was then quite adequate. The recent increase in irrigated area shows clearly that it will be very difficult to supply sufficient water when the remaining 1,000 acres is place in cultivation. The program suggest in this inventory is, therefore, almost entirely directed to two ends; (1), to increase the efficiency of the pumping plant to the highest max- imum that can be sustained; (2), to reduce canal and lateral losses and all forms of waste to a minimum. For some years the District, in its operation of the system, has been reclaiming with small portable pump units all the surface waste and re- turn flow that could be pumped to its canals under reasonable lifts and such sup- plies were fairly large and constant. Due to the long, narrow shape of the irrigated area and the presence of two distribution canals, no laterals are long. All laterals are provided !lad main- tained by the irrigtors and in recent years these people have lined a great length of lateral, especially at the upper end of the project. To assist in suoh lining the District has,in many cases, contributed cement or other materials, on the theory that such imp~ovements greatly aided its problem of supplying necessary water. The inventory contains an item which would permit even greater contribu- tions than the District has made in the past. It seems probable that the common tail water elevation of the'pumpi~and power plants is higher than it should be, in view of the fact~that in recent years Colorado river has degraded ;i.ts bed by several feet. However, it is doubtful if a > :.~'"~e C advantage can be taken of this fact. The pumpinqplant is now operating at a draft head of over 10 feet, and the seal over the elbow draft tubes of the power plant appears to be no more than adequate. In any case, the tailwater elevation must be maintained high enough to permit, when the river is low, of the by-passing of this power water upstream for the service of the Grand Valley Irrigation Company. It is believed, however, that the present by-pass, and especialJy the necessary check at its upper end, ane higher than is needed. Since present operation through this by- pass results in a 10 percent reduction of pumping capacity for the Orchard Mesa District, and probably in some reduction of power plant output, it seems desirable that a check of by-pass elevations and a reduction in them, if possible, shou~d be attempted. The check gates in the tail race are a makeshift affair and gates that can be readily operated and closely controlled are badly needed. While each pump on each irrigation lift is fed from the same penstock as its connected turbine, the delivery pipe for each lift carries the output of both pumps /,(' from points just outside the pumping plant. On both lifts, when both units are /. .I', ..; operating at equal turbine gate openings, one of the pumps is worting against a r'! t"/" much higher lift than the other. For the lp:i!gtlet 1'IT~) the No.4 pump operates con-Jr<(ll. tinually at 165 feet while the No. 3 pu~p operates against only 150 feet.~The No. 2 pump likewise, o,!1erates against a head of 105 feet, while the No.1 pump has only 90 feet head. Th~~~~ating heads include the pipe friction of penstock and del- ivery pipe, although tlle static heads, as already given are only those from the main canal level to the levels of the distribution canals. While a marked inrease ~