Impact of climate change on aquatic resources has taken on a global dimension. In northern Ghana perennial water shortage is a major problem. Water storage and fisheries productivity in reservoirs such as Vea in Upper East Region is expected to be impacted upon by climate change in varying degrees. Extreme high rainfall in the region was assessed through comprehensive integrated approach. Future extreme high rainfall values were projected based on IPCC scenarios: SRES A1FI and B2 with climate mid sensitivity and GCM: HADCM3, run on SimCLIM model. Projections revealed that extreme high rainfall will increase under both climate change scenarios and high runoff events like floods will intensify. These might lead to increased rainwater for storage and quicken siltation in the Vea Reservoir. Annual fish production (fish landings) 1991-2009 showed peak oscillation trend which coincided with historic flood events of 1995 and 1997 for the 1990s; with 2005 and 2007 for the 2000s, respectively. Vea Reservoir under prevailing conditions is oligotrophic but could become eutrophic under climate change. The cascading effect could be on the Cichlidae: Tilapia zillii and Oreochromis niloticus.