Because of the natural flooding and sub-irrigation i n the 

 floodplain any "new" tloodplain development would be 

 redundant (it is in effect irrigated now). So, new water- 

 spreading irrigation would require pumping water to lev- 

 eled or contour diked systems outside the flood plain. Ac- 

 cording to the SCS, these systems generally cost between 

 $300 toS600 per acre with an annual pumping cost of from 

 SlO to S20 per acre. The expected yield for this type of 

 development would vary, depending on the duration of the 

 high flows and spring rain, from 1 to 3 tons per acre. The 

 benefit/cost ratio of this type of system is decidedly less than 

 1:1, making them economically infeasible. 



2. Current Agricultural Land Use on the Reservation 



On July 6, 1 990, members of the RWRCC stafFflew the 

 length of the Rosebud Creek drainage on the Northern 

 Cheyenne Indian Reservation. A video record of this flight 



was made, and approximately 100 still photographs were 

 taken of the valley floor. 



Aerial photographs were borrowed from the Water 

 Rights Bureau in Miles City and copied and were used to 

 distinguish currently cropped lands into sub-irrigated, ir- 

 rigated, and dry land categories. The video tape and the still 

 photos were used to corroborate the following rough esti- 

 mates of currently irrigated lands on the Reservation: 



naturally sub-irrigated 



currently irrigated 

 (man-made systems) 



- 1,31 1 acres 

 525 acres 



1 ,836 acres 



More accurate estimates could be achieved by field 

 investigations. 



29 



