RUM RIVER AT CAMBRIDGE. Location. At highway bridge 1⁄2 mile west of Cambridge. No tributary within several miles. Records available.-June 12, 1909, to December 31, 1912. Drainage area.-1,160 square miles. Gage.-Vertical staff; datum unchanged since established. Discharge measurements.-Made from the bridge. Regulation. At St. Francis, 20 miles below Cambridge by river, there is a 10 foot dam and power plant. Between the crest of the dam and the water surface at the gaging station there is a difference in elevation of about 6 feet. The fact that morning and evening gage heights during the low water period show no consistent change, being for the most part the same, indicates that the St. Francis dam has very little effect on the flow at this station, even though the flow may fall below the crest during certain portions of the day. The only dam above Cambridge is one at Milaca, which is used to form a pool from which water is pumped. Winter flow. From December to March, discharge measurements are made through ice to determine the winter flow. Accuracy. During the summer of 1911 and 1912 grass grew in the channel to such an extent that it caused backwater in varying amount at the gage. Therefore during that period the records cannot be considered better than fair. The remainder of the records are believed to be good. Daily discharge, in second-feet, of Rum River at Cambridge. "Daily discharge computed from a fairly well defined rating curve, except Mar. 1 to 11, 1910, for which period it was estimated. Daily discharge, in second-feet, of Rum River at Cambridge-Continued. Day. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. "Daily discharge computed from a fairly well defined rating curve, except Mar. 1 to 11, 1910, for which period it was estimated. Daily discharge computed from a rating curve not very well defined which was applied indirectly during 1911 and 1912 owing to shifting conditions. Daily discharge, in second-feet, of Rum River at Cambridge-Continued. Daily discharge computed from a rating curve not very well defined which was applied indirectly during 1911 and 1912 owing to shifting conditions. Monthly discharge of Rum River at Cambridge-Continued. "Estimated from ice measurements and semi-weekly gage heights. Estimated. RUM RIVER NEAR ANOKA. Location. -At highway bridge on line between ranges 24 and 25 west, and 5 miles north of Anoka. The nearest tributary of importance is Cedar Creek which enters 21⁄2 miles above. Records available.-May 8, 1905, to July 21, 1906; June 22, 1909, to November 23, 1909. Drainage area. -1,430 square miles. Gage. Chain gage which remained permanent. Channel. Slightly within the influence of the dam at Anoka, and therefore slightly shifting. Discharge measurements.-Made from bridge. Winter flow.-Ice caused backwater during the winter months and the observations were discontinued. Regulation. The dam at St. Francis, twelve miles above holds back the night flow during the low water period, sufficiently to show a difference between night and morning readings of a tenth of a foot. |