Poorly defined water courses are not shown. Aggraded flats are valley floors without well-defined stream channels or scars. They are shown as soil. Canals and ditches, whether for navigation, irrigation, or drainage, are plotted to scale if they are wide enough. Otherwise they are shown by the single-line symbol.
Arrows indicate the direction of flow.
Generally, both the main ditches and important laterals of irrigation systems are shown. Large canals and ditches are named on the field sheets if they have names. On the map, canals and ditches must be distinguishable from roads. Lakes, ponds, and reservation are delineated to scale on field sheets. The boundary marks the normal water level, which may not be the shoreline observed and recorded at the time of the survey.