Field‐Based Evaluations of Horizontal Flat‐Plate Fish Screens

Abstract

Diversions from streams are often screened to prevent the loss of or injury to fish. Hydraulic criteria meant to protect fish that encounter screens have been developed, but primarily for screens that are vertical to the water flow rather than horizontal. For this reason, we measured selected hydraulic variables and released wild rainbow trout Oncorhynchus mykiss over two types of horizontal flat‐plate fish screens in the field. Our goal was to assess the efficacy of these screens under a variety of conditions in the field and provide information that could be used to develop criteria for safe fish passage. We evaluated three different inverted‐weir screens over a range of stream (0.24–1.77 m3/s) and diversion flows (0.10–0.31 m3/s). Approach velocities (AVs) ranged from 3 to 8 cm/s and sweeping velocities (SVs) from 69 to 143 cm/s. We also evaluated a simple backwatered screen over stream flows of 0.23–0.79 m3/s and diversion flows of 0.08–0.32 m3/s. The mean SVs for this screen ranged from 15 to 66 cm/s and the mean AVs from 1 to 5 cm/s. The survival rates of fish held for 24 h after passage over these screens exceeded 98%. Overall, the number of fish–screen contacts was low and the injuries related to passage were infrequent and consisted primarily of minor fin injuries. Our results indicate that screens of this type have great potential as safe and effective fish screens for small diversions. Care must be taken, however, to avoid operating conditions that produce shallow or no water over the screen surface, situations of high AVs and low SVs at backwatered screens, and situations producing a localized high AV with spiraling flow.

Field‐Based Evaluations of Horizontal Flat‐Plate Fish Screens, II: Testing of a Unique Off‐Stream Channel Device—the Farmers Screen

“…We also never had problems with debris loading on the screen, although our tests were done at times when the amount of debris was sparse. Our results were similar to those of Rose et al (2008), who reported minimal injuries and low mortality of rainbow trout (45-250 mm) after passage over backwatered and inverted-weir horizontal flatplate screens in Oregon. Rose et al (2008) evaluated ranges of sweeping (15-143 cm/s) and approach (1-8 cm/s) velocities that were similar to ours.…”

“…Our results were similar to those of Rose et al (2008), who reported minimal injuries and low mortality of rainbow trout (45-250 mm) after passage over backwatered and inverted-weir horizontal flatplate screens in Oregon. Rose et al (2008) evaluated ranges of sweeping (15-143 cm/s) and approach (1-8 cm/s) velocities that were similar to ours. Other studies evaluated various designs of vertically oriented screens and reported results similar to ours for juvenile splittail Pogonichthys macrolepidotus (mean length of about 6 cm; Danley et al 2002), bull trout (median length, 25 mm; Zydlewski and Johnson 2002), and juvenile Chinook salmon O. tshawytscha (4.4-7.9 cm; Swanson et al 2004).…”

“…Recently, the development of unique horizontal flat-plate fish screens offer designs that may be less expensive to install and offer simpler, more passive (i.e., no moving parts) operation than other screens. Research on the hydraulic characteristics and biological effects of some flat-plate screens has resulted in a greater understanding of how they work (Frizell and Mefford 2001) and shown few negative effects (e.g., injury or mortality) on juvenile bull trout Salvelinus confluentus or rainbow trout Oncorhynchus mykiss that passed over such screens (Beyers and Bestgen 2001;Rose et al 2008). However, more work is needed to fully evaluate their performance.…”

“…The screens are manufactured in various sizes and can accommodate flows ranging from 0.01 to over 4.5 m 3 /s (0.5-160 ft 3 /s). There are many small unscreened or insufficiently screened diversions with flow less than 1.4 m 3 /s (50 ft 3 /s) in the western USA, and small diversions can take a high percentage of the flow from small streams; most larger diversions have already been screened (Moyle and Israel 2005;Rose et al 2008). We therefore decided to test a small version of the Farmers Screen because of the great potential for installing these devices in many areas.…”

Behavior and potential threats to survival of migrating lamprey ammocoetes and macrophthalmia

“…Ammocoetes can be quite small (typically < 40 mm long, < 2mm in width as yearlings), and protecting them from 41 entrainment presents a unique challenge (Rose et al 2008). Macrophthalmia are usually larger (75-200 mm, 6-11 42 mm wide at eye), but their movements can occur over protracted periods (Luzier and 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 5 downstream movements to find suitable habitat for burrowing and feeding (Hardisty and Potter 1971, Potter 1980 Dawson et al In Press).…”