4 6 



quantity and so reduces the flow, and partly because the 

 reclamations effected have entailed the loss of certain of 

 the old sluices. This latter cause has operated in a 

 specially adverse manner upon Valle Mezzano, the 

 greatest section in the lagoon, for to-day it possesses but 

 a single sluice admitting water from the river Reno 

 instead of the three it once had. 



While the fact cannot be disputed that the evils 

 which result from certain defects in the present physical 

 condition of the lagoon may be mitigated in large part 

 if freer commumcation be established between the laeoon 

 and the sea and if larger supplies of river water can be 

 made available, the methods of so doing have been the 

 subject of much controversy. The present is not the 

 place to discuss the details of the arguments, as their 

 interest and bearing are almost entirely local and special 

 to the conditions of this particular lagoon. Additional 

 river sluices and better regulation of those existing are 

 among the most obvious remedies, but the river supplies 

 are limited because of several considerations, some of 

 which have been alluded to above, and permanent relief 

 can only be obtained if the supply of sea-water be enor- 

 mously increased. At present the lagoon is virtually 

 cut off from free access to the sea during the period from 

 May to the end of January. From May to September, 

 the massive palisades of the tresse form all but imper- 

 meable obstacles, while during the fishing season between 

 September and January the equally massive walls of the 

 labyrinths offer as effective barriers to the tidal flow. 

 Besides, what is gained by the lagoon during the flow is 

 lost in large measure during the ebb. Either some 

 radical alteration must be made in the methods of 

 penning in and of trapping the fish, whereby the various 

 barriers may permit free flow and ebb at least during the 

 dry season, when evaporation is intense — a proposition 

 no one has solved yet, or else means must be adopted 

 to greatly increase the quantity of water brought in 

 by the flood and then to prevent its reflux. The 

 difficulty of passing sufficient water in during flood-tide 

 by means of the restricted channels which alone are 

 available is, however, practically impossible so long as 

 the present method of constructing labyrinths and tresse 

 is followed. 



