SEWAGE CONTAMINATIOlSr OF OYSTEE BEDS. 



211 



Table II. — Analysis of vmter samples collected off I'omham. 



Date and station. 



Fcbruartj 26, flood tide. 



Station 1, surface tube 



deep tube 



2, surface tube 



deep tube 



3, surface tube 



deep tube 



Marcli ;.', tidcfcdling. 



Station 1, surface tube 



deep tube 



2, surface tube 



deep tube 



3, surface tube 



deep tube 



March — , tide falling. 



Station 1, surface tube 



deep tube 



2, surface tube 



deep tube 



3, surface tube 



deep tube 



Dextrose 

 fermented. 



Other fecal 

 bacteria. 



a Not made. 



The data given iu Tables I and II .show clearly that the water of the 

 riv^er in the immediate neighborhood of Fields Point and also at Pom- 

 ham, 1\ miles below this point, is polluted by sewage to a very con- 

 siderable extent, since it is possible to isolate B. coll from practically^ 

 everj^ sample collected within this area. This statement seems to be 

 trustworth}^ whether tlie tide is making upstream or falling, or 

 whether the samples are collected when there is a stiff breeze from the 

 southerly direction, thus tending to drive an increased amount of 

 water up the river, or during a flat calm. 



An attempt to estimate the number of bacteria per cubic centimeter 

 in the water about Fields Point was made by inoculating nutrient gel- 

 atin plates from two of the samples collected April 10 and keeping 

 them three days at room temperature. Four plates were made from 

 each sample, and the average count of colonies developing was esti- 

 mated as follows: Station 2, surface water, 1,500,000 bacteria per 

 cubic centimeter; station 3, surface water, 2,000,000 bacteria per cubic 

 centimeter. Thus the quantitative as well as qualitative analysis 

 points to high organic pollution of these waters. 



The second series of samples was collected from a section of the 

 river from 2 to 2|^ miles from Fields Point. These samples Vv'ere taken 

 at five stations, as follows: Station 1 over the northern part and sta- 

 tion 2 at the southern end of the o3"ster grounds off Sabins Point; 

 on the Pawtuxet shore, station 3 in the shallow water covering the 

 sand beach west of the Rhode Island Yacht Club house, station 4 off 

 the end of the club wharf, and station 5 in shallow water again, from 

 the shore near the end of Pawtuxet Neck. Four trips were made to 

 the first two of these stations; but one to those on the western shore 

 of the river. The result of these analyses is included in Table III. 



