Water

The Tulare Basin hosts an astonishing array of natural and man-made water features in this hydrologically distinct region. From lakes, ponds, sloughs, marshes, and vernal pools to irrigation ditches, pumping structures, canals, and waterways, these water elements provide flood control, groundwater recharge, conveyance, water storage, and habitat for plants and animals.

Tulare Basin Hydrologic Unit and its Setting

As defined by the Tulare Basin Wildlife Partners (TBWP), the Tulare Basin hydrologic unit includes the valley floor alluvial fans of Kings, Kaweah, Tule, and Kern rivers, as well as a few lesser streams from the Sierra foothills; the historic lake beds in the Basin area; and the southwestern uplands. While similar to the definition of the Tulare Basin hydrologic unit used by the United States Geological Survey and the California Department of Water Resources, TBWP does not include the Fresno-Clovis and Little Panoche Creek sub-watersheds, which flow directly into the San Joaquin River Basin watershed. The only connection between the Tulare Basin hydrologic unit, as referred to by TBWP, and the San Joaquin River Basin watershed is where the Fresno Slough/James Bypass system joins the San Joaquin River at Mendota Pool.

While most Sierra Nevada rivers flow into the San Joaquin Valley and ultimately out to the Pacific Ocean, the four major southern Sierra rivers: the Kings, Kaweah, Tule, and Kern, as well as a number of lesser streams, including Deer Creek, White River, and Poso Creek, all flow west across the Central Valley into the Tulare Basin's terminal lakes. These rivers and creeks historically formed broad deltaic fans as they emerged from the foothills and flowed un-dammed to the Tulare Basin in dozens of channels and sloughs that shifted periodically during flood events. Today, dams manage water flow on the Kings, Kaweah, Tule, and Kern rivers.

Of the five lakes in the Tulare Basin, Tulare Lake, historically, was the largest freshwater lake in the contiguous United States west of the Mississippi River. This lake connected with the Kern, Buena Vista, Goose, and Summit lakes by a system of shallow, slow-moving, tule-lined sloughs. In the mid-1800s, this system covered an average of 44 square miles in the Basin. After contracting during dry years, the lake perimeters could expand to over 100 square miles during particularly wet years.

Water-Dependent Natural Diversity
The Tulare Basin historically supported an amazing complex of wetland habitats unique in the world. This largely flat and arid region served as the floodplain for water flowing west from the southern Sierra Nevada, north from the Transverse Ranges, as well as from small intermittent arroyos flowing east from the Coast Ranges.

Oak woodlands and riparian forests formed green corridors across the broad prairie on the eastern edge of the Tulare Basin. Freshwater tule marshes and alkaline wetlands adorned the slow-moving sloughs and shallow margins of Kern, Buena Vista, Goose, Tulare, and Summit lakes. Emergent marsh vegetation, such as tules and cattails, grew in permanent standing water at the shallow edges of freshwater wetlands. Upslope from the marshes, water intermittently flooded iodine bush scrub and alkali grassland habitats.

This highly-productive, shallow water system supported abundant populations of endemic lake-adapted fishes such that American white pelicans (Pelacanus erythrorhynchos) nested by the thousands on islands in Tulare Lake and Buena Vista Lake. The Tulare Basin's extensive wetland habitats historically attracted significant numbers of resident and migratory waterbirds, including grebes, pelicans, cormorants, herons, egrets, ibises, geese, swans, ducks, rails, sandhill cranes, plovers, stilts, avocets, sandpipers, phalaropes, gulls, and terns.

Land-Use & Water Changes
While scattered remnants of the original wetland and upland habitats remain, two centuries of European settlement extensively modified water supply and delivery in this pristine landscape. As early as 1851, humans implemented irrigated agriculture and began building canals and diversion structures. Irrigation infrastructure for agriculture upstream from Tulare Lake slowly cut off the lake from its source waters and the lake shrunk. By 1899, Tulare Lake was dry for the first time in history.

Settlers filed land claims for this "newly appeared" farmland and continued to build structures and modify natural waterways to control water flow and minimize flooding. Conversion of the lakebed proceeded rapidly with levee construction and the formation of reclamation districts. The Tulare Lakebed has remained dry for most of the twentieth century but whenever heavy runoff brought water back to the area, most of the waterbirds which comprised the historic avifauna of the region returned in impressive numbers to the wetlands of the Tulare Basin.

Water Management
Today, the Tulare Basin receives water from five sources: precipitation, runoff from local rivers and streams, groundwater, delivery via the State Water Project, and delivery by the Central Valley Project. During much of the time, irrigation and other water supply requirements determine the quantity and movement of water in the Tulare Basin. In years of high winter rainfall and spring snowmelt runoff, flood control concerns influence water movement. In average and drier years, surface water moves throughout the Basin primarily by gravity flow in natural stream channels and constructed canals or ditches. In some locations, pumping distributes irrigation water or drains water.

A variety of entities, including public agencies; irrigation, water storage, drainage, and other districts; water banks; and private landowners manage water in the Tulare Basin. This requires careful planning and balance to provide water for diverse needs, such as wildlife habitat and wetland values; agricultural needs; groundwater banking and recharge; subsurface irrigation tailwater disposal; flood control; storage; conveyance; and other purposes.

The Future of Tulare Basin Water
Water quality, supply, flood control, storage, groundwater recharge, and other water challenges affect all of us. TBWP is concerned about the long-term viability of the water supplies available to the Tulare Basin, as well as health of the Kings, Kaweah, Tule and Kern River watersheds and the many smaller streams which flow into the Tulare Basin.

TBWP is currently working with a variety of local and state-wide partners to develop several integrated regional water management plans within the Tulare Basin. These efforts seek to predict and meet the demand for agricultural, municipal, industrial, and environmental water supply, water quality, and flood control needs now and into the future. TBWP is committed to collaborating and leading efforts that combine the needs of communities, industry, agriculture, wetlands, and wildlife to meet the long-term sustainable needs of the region.