American cranberry (Vaccinium macrocarpon) production sites are often flooded for pest control and crop harvest. However, little is known about how this practice affects vines. A survey was conducted in Massachusetts over a 3-year period to determine the effect of spring, fall, and winter floods on total nonstructural carbohydrate concentration (TNSC) of cranberry uprights of four cultivars. With a few exceptions, TNSC generally was unaffected or increased during the course of the 1-month “late water” flood held from mid-April to mid-May. The 48-hour “flash” flood, held in mid- to late May, generally had little effect on vine TNSC. Fall “harvest” floods, which ranged in duration from 3 to 27 days, often resulted in a decrease in TNSC, with greater decreases in TNSC occurring in early fall floods compared to late fall floods. Decreases in TNSC during the harvest flood were as great as 42%. “Winter” floods had little effect on TNSC. Path coefficient analysis indicated that flood duration, date of application, water temperature, and dissolved oxygen concentration all impacted vine TNSC during the flood, while floodwater depth had little effect. Water clarity (i.e., light penetration to the vines during the flood) also appeared to have little impact. Due to the frequent observation of TNSC decline during fall flooding, it is possible that yield potential of cranberry vines is reduced by current flooding practices.