Screen intake assemblies and related methods of fabrication and operation that improve both operational performance and structural strength. The screen intake assembly can include one or more screen portions that run substantially and continually along the length of the screen assembly to provide increase fluid intake and uniform flow. The screen intake assembly can comprise a central manifold having an exterior manifold screen portion to provide additional filtering capacity. The screen intake assembly can be used alone or in combination with internal flow modifier structures to increase fluid intake and uniformity. Internal flow modifiers can include a perforated flow modifier pipe, an internal flow modifier pipe, and/or converging flow modifiers. The screen intake assembly can include cleaning systems that operate continuously or on demand.