Procke^dings 01^ Fii^TH AnnuaIv Meeting 51 



line. That portion of this area which is still infested is shown 

 by dot-shading, and the depth of the shading is intended to cor- 

 respond with the density of infestation. 



The occurrence of infested areas in the region of the salt 

 marsh, which is marked drained, is due to incompleteness of the 

 drainage systems established. Anything like complete control 

 throughout this large area involves the installation of more com- 

 plete drainage systems than now exist in more than a very few 

 places. For the purpose of showing the lack of completeness in 

 the drainage systems, the estimates in table i, prepared about 

 January i, 191 7, are presented. 



In Bergen, the lower end of Ocean, Atlantic and Cape May, 

 as in certain Hmited areas in other counties, the ground which 

 was covered was sufficiently drained, and the percentage marked 

 as undrained represents areas that are practically untouched. In 

 the other counties, however, with the limited areas excepted, the 

 shortage is due to lack of completeness within areas already cov- 

 ered by drainage systems. 



The same point is shown by the fact that the average number 

 of linear feet per acre in the area covered is about 120, while 

 rather careful investigations of the past three years seem to show 

 that about 300 linear feet of 10 by 30-inch ditching are necessary 

 to effect mosquito drainage in open salt meadows. In sections 

 shut in by railway grades, roadways, and fills, the number of 

 feet required may be less, but the cost of dike, sluice and tide- 

 gate construction, of the installation of pumps, and the mainte- 

 nance of all will more than offset the difference. 



The progress in salt marsh ditching from the beginning is 

 shown in table 2. 



In addition to the figures given, many acres have been protected 

 by dikes and outleted through sluices, involving the building of 

 17.2 miles of dikes and the installation of 76 sluices, affording 

 842 square feet of cross-section opening. 



With the exception of some drainage carried out very early 

 on the Newark, Elizabeth and Jersey City meadows, all this work 

 has been done by the State Agricultural Experiment Station and 

 the county units. The latter began in 1912. Table 3 shows the 

 relative part played by each. 



