Extensive study of the use of late water (LW, a 4-week spring flood used to control pests) in modern cranberry production systems began in 1993, focused on the effects of the flood on pests and the cranberry plants, and compared LW to companion early water (EW, no spring flood) bogs and to their own histories. In 1993 and 1994, LW bogs had yields comparable to EW controls with N fertilizer reductions of 35% and 60%. In the year following LW, N use returned to pre-LW levels. In 1995, N use was reduced by 65%. However, yield on LW bogs was reduced in 1995, at least in part due to anomalous winter weather and drought. Upright length and density did not differ between LW and EW bogs (1993–95). This may have been due to reduced N dose offsetting any growth-promoting effects of LW. In 1994 and 1995, LW bogs had fewer flowers than EW bogs, but increased fruit set compensated in 1994. LW may adversely affect yield in some years but this could be offset by reduced production costs or increased yields in following years. Cost/return budgets are being studied.