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i . SCHARF AND ASSOCIATfS 410 IOU1'K ClOLORAOOIOULIi:VARO DIJWIIIf, CO\.ORADO 80222 laOS>> 1122-1281 RECEIVED J,UN 11 197.5 COLO. WATER tCOIlSERYA T:l.O,tI 8QJ\&1l Juae 10, 1975 ; Mr. Gary Z. Fortner, Direotor of Planning Office of the Planning Co=dss1on Weld County, Colorado 1516 Hospital Road Greeley, Colorado 80631 near Mr. Portner I I regret that we cannot offer allletl.Clments to our origiDal mapping proposal of the Big Thompson River which would reduce the cost and still meet National Map Accuracy Standards. ! f. f I f The specifications as set forth by the Colorado Wster Conservation Board are well written to assure accuracy and quality of mapping of your project. The cost of mapping is largely affected by the scale of aerial photoaraphy. The hiaher we fly, the fewer aerial photos are required to cover a given area and a resulting reduction in cost of photography, ground control and stereoplotting. However, as we iucrease the flyina altitude, the accuracy of the stereoplotting is reduced inversely pro- portional. r .. t i' , , ! .. , , , \ , , , l ~- . In the competition for lllappina cOll.tractlil, it is very easy for U8 to become overly confident of our ebilities. Wort_tely few IllapS are adequately check.d for accuracy and many aJ;e accepted without any checks wbat.oever. Under opt1laum cOl1d:ltiou of photography, control, stereo- plotter cd operator, a IllaP IllaY prove to be far aore accurate than required by the specif1catiOll.l aacl .. a rellUlt the lllapper U8e8 this exalllple to ju.tify 10,cr888111g the flyina altitude for .11 future work. At the request of the Client w:tthout any auarantees of accuracy, we heve compiled 2' contour. from 1" . 1000' scale photography. Approxi- lllately 50% of .lIGh IIl8ppina has met tha National Map Accuracy Standards. SOllie projects do not warrant . hiah degree of accuracy and a compromise 111 accuracy i. justified :If costs can be reduced.