Photo I. Fish impinged on the outer portion of the screen against the screen in area 



Proper 

 operation and 



maintenance of a 

 fish screen is 

 equally important 

 to quality screen 

 design (Nordlum 

 1996) in order to 

 assure long-term 

 effectiveness and 

 fimction. In the 

 Blackfoot River 

 drainage, 

 inadequate 

 maintenance has 

 reduced the 



effectiveness of 

 many mechanical 

 fish screens 



(paddlewheel and rotating drum). Because it has no mechanical parts, the turbulent 

 fountain screen requires less maintenance than conventional fish screens and is cheaper to 

 install and use. The total cost of the entire modified turbulent fountain system including 

 the head gate was $9,900, approximately 75% of the cost of self-powered paddlewheel 

 driven fish screen and head gate of comparable flow capacity (Montana Fish, Wildlife 

 and Parks data). While comparable in cost to electrically powered rotating drums of 

 similar capacity, a turbulent fountain required lower maintenance at less expense. 

 Throughout the three summers of use, the turbulent fountain required less manual 

 cleaning than either traditional paddlewheel driven flat-plate screens or electrically 

 powered rotating drums. 



With proper design and construction, a turbulent fountain fish screen, as an 

 integrated diversion structure, can meet multiple objectives. These include: 1) volume 

 control to an irrigation system and automatic removal of debris from a pipeline, 2) the 

 elimination of entrainment into diversion ditches and the return of fish directly back to 

 the stream immediately below the diversion point, 3) reduced impingement, 4) minimal 

 screen maintenance, and 5) a cost-effective screening device. Unfortunately turbulent 

 fountains have not been designed for volumes >0.15 m s although Bondurant and 

 Kemper (1985) suggest designs for higher flows are possible. Required hydraulic 

 differential for larger diversions should also be evaluated in order to identify specific site 

 requirements. Although turbulent fountain screens appear to minimize entrainment and 

 impingement on small diversions, we did not fully measure all aspects of screen 

 velocities (approach or sweeping), nor all aspects of physical contact of fish with the 

 screen. Future studies should also evaluate screen injury potential such as scale loss, as 

 well as other design improvements in order to expand this technology to areas where 

 formal fish screening criteria currently preclude use of turbulent fountain fish screens. 



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