SECTION IV 

 METHODS AND MATERIALS 



This section describes the methods and materials used in 

 monitoring tile drainage systems for the period of study. 



Monitor ing Tile Drainage Systems 



A brief history of tile drain monitoring is presented to 

 show the necessity for an intensified monitoring program. A 

 greater emphasis was placed on the selection of tile drains, 

 field monitoring techniques, and collection of agricultural 

 and soils data during the more recent studies than in the 

 past . 



Historical Monitoring 



Initial investigations of tile drainage began in 1959 as 

 part of the Agricultural Waste Water Quality Studies, a 

 coooerative program between the Department of Water 

 Resources and the Water Resources Center of the University 

 of California. During these studies, the emphasis was 

 placed on the quantity and quality of surface and subsurface 

 agricultural wastewater. The frequency of sampling for tile 

 systems at that time was somewhat limited; 104 nutrient 

 samples were collected from 29 systems over a four-year 

 period. Most of these systems (25 out of 29) were located 

 in the central area; the other four were located in the 

 northern area. 



Samples were not collected from tile systems in 1964 and 

 1955, However, in 1966, seven tile systems were selected 

 for more intensified sampling in the central area. Later 

 the same year, reconnaissance investigations showed that 

 drainage from other tile systems in the same area contained 

 much higher concentrations of nitrogen than those currently 

 being sampled. At the same time, drainage from tile systems 

 in the Byron-Westley and Tulare Lake areas was found to be 

 lower in nitrogen concentrations. The foregoing investiga- 

 tions led to the eventual expansion of the monitoring 

 program to include as many as 40 individual systems in 196? 

 and 42 systems in I968. Intensive investigations were not 

 initiated in the Byron-Westley area until May 196?; all 

 other major tiled areas were sampled for the full calendar 

 year. In I968, all 42 tile systems within the major tiled 

 areas were sampled intensively for the entire year. In 

 addition, I8 satellite systems and a few isolated tile 



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