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Figure 17. Small shearing wedgewire screen used on the inlet water to Horsethief Canyon State Wildlife Area's threatened and endangered fish grow-out ponds. This screen was designed by Aquadyne Inc. (Healdsburg, CA). screens impede the movement of nonnative fish into 10 reclaimed waterfowl ponds/wetlands, and six T&E grow-out ponds. The aperture of these screens was 0.5mm (Figure 18) and the tilt of the wire was five degrees, which imparts a shearing effect. Fouling was a significant problem with the larger screen used on the field, pond, and wetland inlet. It was installed at too shallow of an angle (15 degrees) on the intake box to impart a self-cleaning effect (Figure 19). This screen required cleaning at least once a day depending on the debris load in the river. However, the smaller screen on the inlet water to the endangered fish ponds was set at a 45 degree angle, and has required no maintenance (Figure 20). We observed larval fish impinged on the large intake screen (Figure 21). However, green sunfish, fathead minnow, common carp, and mosquitofish (in order of incidence) were also sampled in ponds on the property following reclamations, and are believed to have passed through this intake screen as larvae. Similarly, larval/juvenile fathead minnow and red shiner were sampled in the endangered fish ponds after they had been emptied, dried and refilled with screened inlet water (Figure 22). 38