Significant improvements are being made in fish guidance systems used for downstream anadromous juvenile fish passage such as Floating Surface Collectors at Upper Baker Lake, Swift Reservoir, and Lower Baker Lake. These systems include converging vertical wedge-wire dewatering screens that pass flow pumped by submerged low-head axial pumps. The guidelines by which these systems are designed are set forth by the National Marine and Fisheries Service (NMFS), and require adherence to criteria such as transport velocity, screen approach velocity, and acceleration. As part of the final stage of commissioning, hydraulic balancing and operational evaluation are conducted using velocity and water level meters to adjust baffles for the purpose of distributing flow in accordance with their intended design flows, transport velocity, and screen approach velocity. This paper will discuss the guidelines for design, balancing, and evaluation of these facilities in the context of the practical field operations required to conduct the balancing and evaluation. An account of historical field operations and an analysis of the measurement uncertainties for the instrumentation used and deployment techniques will be provided. A descriptive comparative analysis of the dewatering process between these three projects and the documentation obtained in verifying NMFS criteria have been met will be provided. Lastly, discussion will be provided regarding the correlation between the criteria, how it is measured, and what the documentation validates in terms of fish protection.