Proceedings of Eighth Annual Meeting hi 



out of good drainage systems for the salt marsh has been and is a 

 vital question. Nor is it an easy one because each salt marsh must 

 be dealt with as an entity and experience gained on one meadow 

 often fails to be of use on a contiguous one. In designing a system 

 for the elimination of salt marsh mosquito breeding, the points 

 which apparently are most often forgotten are i — That drainage, not 

 ditching is the ultimate goal to be reached and 2 — That the install- 

 ation of initial drainage measures will inevitably bring about changes 

 to the character of the meadow itself that will tend to decrease the 

 efficiency of the system constructed unless such changes are anti- 

 cipated and provided for. Yielding to expediency in conducting salt 

 marsh drainage operations is a short sighted policy and will even- 

 tually prove to be costly economy. The tendency to cut a lot of 

 ditches to see what they will do with the idea of trying something 

 else if that does not produce the desired result should be guarded 

 against. There is only one practical way to drain any section of salt 

 marsh and that is to make a thorough and comprehensive study of 

 the meadow to be drained noting especially its size, shape and loca- 

 tion, the nature and condition of the soil, whether pervious or irnper- 

 vious, the normal rain-fall to be expected, the rapidity of runoff 

 after heavy rains, the natural water table, the height and reach of 

 tide-water both on the apogee and perigee tides, the amount of water 

 brought to the meadow from adjacent highlands, the nature and 

 extent of natural outlet streams, and the amount and location of the 

 breeding to be destroyed. Much valuable knowledge can be gained 

 by such a survey and with the possession of these facts and due 

 allowance for emergency or peak loads, a comprehensive drainage 

 system can be designed, which should prove adequate and satis- 

 factory under most adverse circumstances. This study should indi- 

 cate clearly whether the marsh is such that open ditching is desirable 

 or whether tide-gates and dikes will be required or whether pumping 

 must be utilized. It will give sufficient data to allow the engineer 

 in charge to arrive at proper conclusions as to width, depth, and 

 spacing of the ditching to be dug. It will furnish sufficient informa- 

 tion for the computation of tide-gate cross sections and the prepara- 

 tion of dike specifications. It will afford a basis for determining 

 size and character of pumping outfits needed. Any other method 

 of procedure will finally produce a system of drainage which is com- 

 plicated, unwieldy, difficult to maintain, and worst of all one that is 

 often woefully inefficient. The method of thoroughly studying 

 the situation before starting any work whatsoever may mean a 



