These major tiled areas are geographically separated on the 

 valley floor as shown in Figure 1 and are differentiated 

 from one another in this report by the towns named above. 

 When deemed appropriate, tiled areas are referred to as the 

 northern, central, and southern areas, which correspond to 

 the Byron-Gustine (includes both northernmost tiled areas), 

 Gustine-Mendota, and Tulare Lake Basin areas, respectively. 



Isolated Tile Systems 



A number of isolated tile drainage systems exist throughout 

 the major drainage problem areas and also in several other 

 poorly drained areas, including certain portions along the 

 east side of the Valley at the base of the Sierra Nevada 

 foothills. Most of these systems are isolated, many of them 

 representing localized drainage conditions not particularly 

 representative of the surrounding area. 



Objectives 



The objectives of the monitoring investigations were to: 

 (1) determine the average nutrient concentrations in tile 

 drainage and the average flows from existing tile drainage 

 systems of the San Joaquin Valley, (2) determine the magni- 

 tudes of annual, areal, and seasonal variability of nutrient 

 concentrations and discharges of tile drainage throughout 

 the major tiled areas of the San Joaquin Valley, (3) if 

 possible, correlate observed nutrient concentrations and 

 tile discharges to agricultural practices, and (4) determine 

 whether soil conditions exist that may influence nutrient 

 concentrations or flows of tile drainage systems. 



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