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BULLETIN OF THE BUREAU OF FISHERIES 



SAMPLING STATIONS 



The stations selected for the taking of samples for the biological survey are the 

 same as those that were selected for the sanitary survey by Mr. Crohurst. The 

 locations of these stations are shown on the accompanying map. (Fig. 1.) Most of 

 the stations are on the Mississippi River, of course, but in order to get some com- 

 parative data from unpolluted streams some sampling stations were chosen on the 

 principal tributaries. The stations on the Mississippi River are so distributed that 

 the data obtained represent conditions (1) before any sewage had been added, (2) 

 after all the Minneapolis sewage had been added, (3) after all the St. Paul sewage 



had been added and one tributary had joined the river, (4) after the South St. Paul 

 sewage had been added, and (5) at various distances below South St. Paul. In 

 this way it should be possible to determine, approximately, the extent of the effect 

 of the sewage from the Twin Cities and from South St. Paul. A brief summary of 

 the distribution of the sampling stations follows: 



Station No. 1 is on the Mississippi River above Minneapolis, at the Camden 

 Power Plant, and represents the river before any sewage has entered it. 



Station No. 2 is on the Mississippi River in the Minneapolis area, about 4 miles 

 below No. 1 . The river here is divided by an island into two branches. Considerable 

 sewage has already entered the river above station No. 2. The right branch of the 

 river receives additional sewage at this station and consequently is more polluted 

 than the left branch. 



Station No. 3 is above the Ford Dam, just below Minneapolis. By this time 

 the river has received all the sewage that Minneapolis contributes. The dam here 

 backs up the water, and as a result the current is very slack, so that most of the solid 



Fig. 1 



