about 98 percent of the creek's flow at its mouth. Flow at the 

 Colstrip gage is about 106 percent of that at the mouth 

 (Woessner, et al. 1981, Saul, 1988). Consumption by irri- 

 gation and riparian vegeution and a lack ot appreciable 

 groundwater discharge into the creek downstream from 

 Colstrip reduce saeamflows by the time the creek reaches 

 the Yellowstone River. 



To develop a representative period of record, a 1938 to 

 1974 period of record was synthesized for the USGS gage 

 no. 06295250 (drainage area 799 square miles) at Colstrip 

 and added to measured streamflows from 1974 to 1988 

 (Holnbeck, 198 la, Saul, 1988). The same was done for the 

 USGS gage no. 06296003 (drainage area 1302 square 

 miles) at the creeks mouth near Rosebud. The flows that 

 were exceeded 50 and 80 percent of time are shown in the 

 table below (also see Figure 9). 



On average, the stretch of the Rosebud Creek between 

 Colstrip and its mouth is a slightly losing reach. From 

 October to April, the mean monthly flows at the two gages 

 are roughly equal. During irrigation and growing season. 

 May to September, significant losses occur. 



Based on a seepage run conduaed by Morrison Maierle 

 Inc in November 1977, there is significant groundwater 

 discharge (about 0.14 cubic-feet per second per mile) into 

 Rosebud Creek in the 32-mile upstream reach extending 

 down to Busbv (Woessner, et al. 1981). When effects of 



Muddy and Lame Deer Creeks were subtraaed, the down- 

 stream reach fi-om Busby to the mouth showed a slight loss. 

 The higher elevation coal and clinker aquifers flanking 

 Rosebud Creek and its tributaries in the southern portion of 

 the Northern Cheyenne Reservation are the major con- 

 tributors of the groundwater inflow. 



3. Groundwater 



As in the Tongue River basin, only the alluvial and the 

 deep Madison aquifer can provide yield high enough to be 

 used for inigation (Woessner, et aJ. 1981). Because of its 

 depth (around 6,000 feet), high temperature and high ion 

 concentrauon, the Madison aquifer probably would not be 

 an economicaJ source for irrigation water. The alluvial aqui- 

 fer could provide water for irrigarion; however, withdrawal 

 of water from the alluvium would reduce Rosebud Creek 

 streamflows. An alluvial well used to supply water for an 

 irrigation center pivot on the reservadon may intercept the 

 creek's flow after several days of pumping (Holnbeck, 

 1981b) and dius immediately lower surface water supply 

 Poor quality and low yield in late summer would probably 

 restrict irrigation use of alluvial groundwater (Griffith, 

 Holnbeck, 1982). 



The clinker and coal aquifers, with maximum mea- 

 sured yield of 50 gallons per minute, (Woessner, et al. 1 98 1 ) 

 provide enough water for domesdc and stock water use, but 

 not enough for irrigarion. 



Rosebud Creek Percentile Flowrs 



Annual 



1 7.620 af 



6.753 af 



16.054 af 



5.291 af 



21 



