SUMMARY OF PROJECT RESULTS AND CONCLUSIONS 



Study of 25 floodplain material sites has shown that disturbance result- 

 ing from gravel removal operations can be minimized. Two gravel mining tech- 

 niques were used at the study sites, scraping of surface or near-surface 

 deposits and pit excavation of deep deposits. 



In general, approaches to minimize environmental changes caused by 

 scraping included maintaining buffers between active channels and the work 

 area and avoi ding: 



• Instream work 



• Mining to depths and in locations that induce permanent channel 

 shifts or ponding of water 



• Clearing of riparian vegetation 



• Disturbance to natural banks 



Large rivers and braided rivers generally provide the most accessible 

 gravels for scraping. Gravel mining using scraping technqiues in these areas 

 frequently resulted in the least environmental changes. 



Pit excavations resulted in permanent loss of terrestrial riparian habi- 

 tat, however, many pits increased local habitat diversity. These newly 

 created habitats frequently received concentrated utilization by local 

 fauna, particularly fish, waterfowl, shorebirds, and furbearers. Large 

 quantities of material were excavated using pit mining techniques. Pits that 

 were located on the inactive side of the floodplain, and were separated by 

 vegetated buffers in the range of 50 to 100 m, generally did not influence 

 active channel hydraulics. 



Pits were found to be most beneficial to local fauna when they exhib- 

 ited the following characteristics: 



