Most of the Kaweah River's runoff comes from the mountain watershed above Visalia, which covers a total of . Including all the lands drained and crossed by the river's many distributaries down to the Tulare Lake bed, the Kaweah River hydrologic region covers . The annual runoff of the Kaweah River between 1975 and 1995 was , or about . The river's highest flows are during the peak snowmelt months of May and June; winter flows are usually more of a trickle, although the river often experiences flooding during rainstorms. Most of the water is diverted above Visalia for irrigation and groundwater recharge. With the exception of agricultural wastewater, water rarely flows any further downstream except in wet years. Extremely large storms can temporarily refill Tulare Lake, as occurred most recently in 1997.