Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/364,824, filed Mar. 15, 2002, and having the same title and inventor(s) as above. 

   FIELD OF THE INVENTION 
   The present invention relates to water diversion devices and, more specifically, to in-stream or out-of-stream devices that provide a screen to retains fish, particularly migrating juvenile salmonids, in a non-diverted out flow stream. 
   BACKGROUND OF THE INVENTION 
   The diversion of water from streams and rivers has been an integral part of the development of the industrial and agricultural economies of the Pacific Northwest and other regions. This diverted water has ground grain, generated electric energy, irrigated arid lands, and been used for municipal water supplies and industrial purposes. Typically, the diversions are not screened, resulting in the ready movement of fish from the source streams into diverted water flows and ultimately to their death. In the Pacific Northwest, unscreened water diversions, amongst other causes, have resulted in the extinction of steelhead and salmon from over 50% of their historic range and have dramatically reduced salmon populations in the few remaining rivers and streams that support salmon. In addition, several races of Pacific Northwest salmonid species have gone extinct and several others are now listed as threatened or endangered. 
   During the development of irrigation and hydroelectric facilities, efforts have been made to achieve screened water diversion apparatuses that separate fish and/or debris from the diverted water flow. Generally speaking, these devices have not worked well and for that reason they are rarely used even though required by law in some instances. For example, in its 1996 study of Pacific Northwest salmon, the National Research Council reported that fewer than 1,000 of the 55,000 water diversions in Oregon were screened, and 3,240 were listed as a high priority for screening. 
   Representative fish screen embodiments are shown in U.S. Pat. Nos. 3,938,340 and 4,064,048, issued to Downs and U.S. Pat. No. 4,740,105, issued to Wollander. A common feature of these devices is that the fish screens are arranged substantially vertically. A significant problem with vertically arranged screens is that they are easily fouled or clogged, resulting in burdensome cleaning schedules or elaborate cleaning equipment that is of questionable efficacy (see, for example, the &#39;105 patent). 
   Other screen arrangements are discussed in U.S. Pat. Nos. 4,526,494 and 5,385,428 issued to Eicher and Taft, respectively. These arrangements each employ a submerged diagonally disposed screen that slopes upwardly in the downstream direction. The diagonal screen arrangement promotes rapid movement of water through the screen and, in principal, generates a shear force that pushes smolt up the screen to a bypass mechanism. The rapid movement of water through the screen, however, causes debris and fish (particularly juvenile salmonid species) to be driven into or accumulated at the screen, thus leading to fouling and fish loss. The screens of both the &#39;494 and &#39;428 patents are pivotally mounted for flushing this debris off the screens. In practice, the screens have also required additional cleaning and maintenance. 
   It should also be recognized that the devices of the &#39;494 and &#39;428 patents are for major hydroelectric installations which tend to pass large volumes of water and be much better capitalized than agricultural irrigation districts and the like. The devices of the &#39;494 and &#39;428 patents tend to be prohibitively expensive for low profit margin and non tax or rate payer supported installations such as agricultural fields and rural residential uses, etc. 
   U.S. Pat. No. 6,132,626 issued to Hart for a Liquid Filter teaches a filtration unit that back flushes a screening element when it becomes blinded by solid material. The device of the &#39;626 patent does not provided unimpeded flow past the screen, but rather forces all flow through the screen, except when operating in back flush mode. 
   It should further be recognized that the above-described screened water diversions do not approximate natural conditions, and thus they increase both physical stress on fish and fish mortality. For example, the &#39;340 and &#39;048 patents use a mechanical scoop that collects fish and drops them into a return conduit, while the &#39;105 patent uses fish traps and a tubal transport system. Similarly, the &#39;494 and &#39;428 patents teach submerged conduits that use high velocity water flow through a tilted screen to shear fish off towards a bypass conduit. The &#39;626 patent teaches a closed chamber that traps or pins fish on a screen, subsequently opening a trap door when the movement of pinned fish or other debris is sufficient to prevent fluid passage and activate a release mechanism. These are all unnatural stream features and work against the genetic programming of fish, leading to increase stress, injury and mortality. 
   A need thus exists for a screened water diversion that safely and efficaciously maintains fish in the non-diverted flow. A need also exists for such a screen diversion that approximates natural conditions, is substantially non-fouling, and is easy-to-use and low cost to implement and maintain. 
   In addition, a need exists for such a screened water diversion that embodies one or more of the following aspects: eliminates risk of predation of fish, is not susceptible to a “dry-screen” condition, ensures adequate water depth for passage and greatly minimizes or eliminates risk of screen plugging from sediment, among other aspects. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention provides a screened water diversion that utilizes a submerged screen and overcomes the problems of the prior art. In one embodiment, the present invention includes an input that directs fluid flow downward to a non-diverted passage under a screen. A weir or related item may be provided past the screen to maintain the screen in a substantially submerged condition, though safe fish passage is achieved without this item. If sufficient flows are present, fluid flows both under the screen to the non-diverted output and upward through the screen into a diverted output. 
   This and related embodiments provide many benefits. These benefits include, but are not limited to, providing adequate water for fish, even in low flows; not impeding the timing of fish migration; shielding fish from predators (birds, mammals, etc.) as they pass the screen; significantly reducing the likelihood of sediment lodging in the screen; and providing a potentially smaller screen footprint. 
   These and related objects of the present invention are achieved by use of a bottom fed screened water diversion apparatus as described herein. 
   The attainment of the foregoing and related advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a screened water diversion device in accordance with the present invention. 
       FIGS. 2–3  are a side view and a back view, respectively, of the device of  FIG. 1 . 
       FIGS. 4–5  are a side view and a top view, respectively, of another embodiment of a screened water diversion device in accordance with the present invention. 
       FIGS. 6–7  are a side view and a top view, respectively, of another screened water diversion device in accordance with the present invention. 
       FIGS. 8–9  are alternative screen arrangements in accordance with the present invention. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1 , a perspective view of a screened water diversion device in accordance with the present invention is shown.  FIG. 1  illustrates an input flow  12  from a stream, canal or other fluid conduit that contains migrating fish  11 , such as juvenile salmonids. The fish are shown facing upstream even though they are descending because salmonids generally face upstream during descent, letting the flow of the water carry them down stream. Input flow  12  flows into an input  14  of device  10  and is split between a non-diverted output  20  and a diverted output  30 . Arrow A indicates the non-diverted flow under screen  40 , while arrow B indicates the diverted flow up through and away from screen  40 . The non-diverted flow continues in the stream while the diverted flow may be channeled into a canal  32  or like structure for subsequent irrigation, power generation, or municipal or industrial use, etc. 
   Device  10  of  FIG. 1  may include a ramp or funnel wall  42  that directs fluid at input  14  down under screen  40 . A weir or other mechanism may be provided in the non-diverted flow downstream of the screen and positioned at an appropriate height to permit fish passage at low flows, but to allow diversion through screen  40  only when flow levels are adequate. 
   Referring to  FIG. 2 , a longitudinal side view of device  10  of  FIG. 1  in use is shown. While flow may vary, line  16  is a representative input flow level. This flow at least in part contacts funnel wall  42  from which it is directed downward into an under screen passage  18 . A portion of fluid entering passage  18  flows through to non-diverted output  20 . Another portion flows upward through screen  40 , due to the upstream pressure gradient on fluid at the input. Line  36  is a representative diverted flow level for an input flow level as indicated by line  16 . 
   Flow conditions below, yet near, screen  40  will tend to be more turbulent than lower down in passage  18 . This facilitates passage of juvenile salmonids who will naturally tend to avoid turbulence in favor of a more pronounced downstream flow. Juvenile salmonids also tend to swim lower in a water column when stressed, further increasing the likelihood of successful passage through the screened fluid diversion device of the present invention. Note also that device  10  (and other devices herein) are preferably configured such that the flow of fluid under the screen is more rapid than an average flow rate upward through said screen, thereby passing and not “pinning” fish. 
   Non-diverted output  20  may include a mechanism  22  (weir or other) to determine a flow level relative to screen  40 . This may be a physical characteristic of the site in which the screen is installed. The height of weir  22  may vary. If the top of weir  22  is positioned sufficiently below screen  40 , then low flow levels will provide fish passage, but no diverted output. If the top of weir  22  is near or above screen  40 , then low flow levels will provide low diverted flows and no non-diverted flow. Adjusting weir height provides a management tool for users. Weir height may be modified based on climate, hydrologic, or fish priority considerations. Note that in  FIG. 2  line  26  is a representative non-diverted flow level given an input flow level at line  16 . 
   Referring to  FIG. 3 , a back view of device  10  of  FIG. 2  is shown.  FIG. 3  illustrates the top of weir  22  being at the same level as screen  40 . Note that this arrangement may vary as discussed above.  FIG. 3  illustrates the relative levels of the input, diverted and non-diverted flows  16 , 36 , 26 , the top of end wall  44  and the non-diverted and diverted outputs  20 , 30 .  FIG. 3  also illustrates a low flow channel  29  (shown in phantom lines) that may optionally be provided in weir  22 . This channel is also shown in  FIG. 2 . A low flow channel or the like may be provided if, for example, it is anticipated that flows may be significantly reduced during certain periods of the year. 
   Referring to  FIGS. 4–5 , a side view and a top view of another embodiment of a screened water diversion  110  in accordance with the present invention are respectively shown. Fluid enters via stream  112 . A head gate  113  may be provided to achieve a desired flow level into screened diversion  110  or for other fluid control purposes. Fluid at input  114  passes in the direction of arrow C under a screened diversion structure  160 . High fluid levels or “overflow” may pass over structure  160  in the direction of arrow F. 
   Fluid flowing in the direction of arrow C flows into an under screen passage section  118  from which it passes to a non-diverted output  120 , indicated by arrow D, or through screen  140  to a diverted output  130 , indicated by arrow E. 
     FIG. 5  illustrates that fluid passing upward through screen  140  flows into a diverted flow receiving chamber or reservoir  133 , indicated by arrow G, from which it may pass into a diverted flow conduit or like diverted flow output channel  131  (also shown in  FIG. 4 ). 
   Structure  160  may be formed in a plurality of suitable materials including, but not limited to, wood, metal and/or plastic. Structure  160  may be fixedly mounted or moveably mounted in place. A moveable mounting scenario may include a floating arrangement or an arrangement with adjustable height legs or the like. In a floating arrangement, cables or the like  163  (shown in  FIG. 5 ) or another attachment mechanism may be used to tether or anchor structure  160  in a desired position. In an adjustable height arrangement, legs  161  may include a positioning gear with turnable handle or have telescoping segments that are releasably set at a desired level. Note that structure  160  preferably includes upstream and downstream contouring  162 , for example, a curved structure, that reduces flow turbulence. 
     FIG. 4  shows respective fluid flow levels for the input  116 , diverted  136  and non-diverted  126  flows. 
   In the embodiment of  FIGS. 4–5 , either the height of screen  140  or the height of the weir (or like)  122  may be varied to adjust non-diverted and diverted fluid flows as discussed above. It should be recognized that screens  40 , 140  and structure  160  protects fish from predators while passing through the diversion device. The position of the weir relative to the screen permits fish to pass even at low flow levels. Since the input flow passes under the screen, sediment in the input flow does not foul the screen. 
   While the device  10 , 110  may be built to any suitable or desired dimensions, which may vary depending on site conditions and passage priorities, in at least one embodiment, the height of the under screen passage is less than the width. For example,  FIGS. 1–2 ,  4 – 5 ,  6 – 7  and  8 – 9  illustrate embodiments in which the under screen passage has an average width that is greater than its average height. Also, in some embodiments of the present invention, the surface area of the screen is greater than the cross-sectional area of the under screen passage. The present invention, however, is not limited to these embodiments. For example, the under screen passage, may be configured as a deeper “pool” in which fish may rest. Pools typically hold cooler water at the bottom which is generally favored by juvenile salmonids (elevated water temperature is one, of the leading causes of salmonid fatality). 
   Referring to  FIGS. 6 and 7 , a side view and a plan view of another embodiment of a screened water diversion  210  in accordance with the present invention are respectively shown.  FIGS. 6 and 7  illustrate an input flow  212 , a funnel wall  242 , a screen  240 , a non-diverted output flow  220  and a diverted output flow  230 . These components function or perform in a manner similar to their corresponding components in other embodiments discussed herein. 
     FIG. 7  illustrates that screen  240  may taper from the input towards the non-diverted output and be bordered by a wall or weir  248 . This taper may accommodate for fluid lost to the diverted output canal  232 , and wall  248  may channel fish towards non-diverted output opening  225 . While one embodiment of opening  225  is shown in  FIGS. 6–7 , is should be recognized that many embodiments are possible, including larger and smaller openings, without deviating from the present invention. Device  210  of  FIGS. 6–7 , like the other embodiments herein, is designed to move fish rapidly and safely through the screened diversion device to the non-diverted opening. 
   Referring to  FIGS. 8–9 , alternative screen arrangements in accordance with the present invention are shown.  FIG. 8  illustrates screened device  10  of  FIGS. 1–3 , but with a screen  40  that is angled up towards the non-diverted output  20 . This feature may facilitate movement of debris, particularly floating debris, past the screen towards the non-diverted output rather than impinging on and clogging the screen. While the angle shown is approximately 5–6 degrees, it should be recognized that the angle may be greater, for example, 10 or 20 degrees and even approaching approximately 30, 40 or 50 degrees. The screen may be angled in whole or in part. 
     FIG. 9  illustrates an embodiment in which screen  40  is curved upward towards the non-diverted output. The screen of  FIG. 9  is intended to provide the same or similar function of the screen of  FIG. 8 . 
   The angled up or curved up screens also permit greater access to the under screen passage for cleaning out sediment, etc. 
   Note that devices  10 , 110 , 210  may be provided such that the screen is removably coupled, e.g., pivotally coupled, floating, wholly releasable, etc., from its support structure to provide access for cleaning, maintenance or other purposes. In the embodiment of  FIGS. 1–3 , for example, screen  40  may be pivotably coupled to the funnel wall an configured to releasably seat in a mounting bracket at the bottom of the end wall  44 . Similarly, in  FIGS. 6–7 , the screen may be pivotably coupled (or releasably coupled) to the sidewalls or taper wall  248 . 
   It is apparent from  FIGS. 1–5  and  8 – 9  that devices  10 , 110  may provide an under screen pool that holds water after temporary cessation of flow at inputs  14 , 114  as may occur between rain showers or at other low precipitation or low flow conditions, particularly in the salmon reproduction areas of the Pacific Northwest. 
   While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims.

Technology Category: 4