BIOLOGICAL SURVEY OF THE UPPER MISSISSIPPI RIVER 



141 



material settles out on the bottom. According to information received from Mr. 

 Elsberg, city engineer at Minneapolis, already there is a layer of sludge, 12 feet in 

 depth, behind the dam, and this is accumulating at a rate of 12 inches each year. 



Station No. 4 is on the Minnesota River, about 8 miles above its mouth and about 

 15 miles below the towns of Chaska and Shakopee. The joint population of these 

 two towns is approximately 4,000. 



Station No. 5 is on the Mississippi River, just below St. Paul, a distance of 

 approximately 10 miles below station No. 3. By this time the river has received 

 all the St. Paul sewage and also the discharge from the Minnesota River. The 

 waters of the Minnesota River flow for about a mile over shallow rapids before 

 entering the Mississippi River, and presumably enter the latter in a well-aerated 

 condition. For the discharge of the Minnesota River see Table 2. 



Table 2. — Monthly mean discharge in second-feet for the period October, 1925, to October, 1926 



Date 



Mississippi 



River at 

 Elk River, 

 Minn. 



Minnesota 

 River at 

 the mouth 



Mississippi 

 River at 

 St. Paul 



St. Croix 

 River at 

 the mouth 



Cannon 

 River at 

 the mouth 



Chippewa 

 River at 

 the mouth 



Zumbro 

 River at 

 the mouth 



1925 



October - - 



2,990 

 2,140 



1, 550 



1,060 



947 

 3, 900 

 3, 820 

 2,230 



2, 160 

 2, 150 

 2, 050 

 5,110 

 5, 190 



379 

 335 

 546 



271 



(') 



2,893 

 1,265 

 606 

 325 

 145 

 259 

 1,661 

 0) ' 



4, 370 

 2, 990 



2, 470 



1,880 

 1,680 

 5, 620 

 7, 150 



3, 650 

 2, 860 

 2,590 

 2, 810 

 8, 630 

 9, 970 



1,848 

 1,812 

 1,602 



1,404 

 1,572 

 2, 784 

 4, 392 

 3,060 

 2,820 

 2, 040 

 2,460 

 4,680 

 (») 





3,600 

 3, 906 

 3,416 



2, 458 



2, 276 

 5,712 



12, 768 

 6,841 

 5, 137 



3, 354 

 8,898 



21, 736 

 11, 472 





November. - 







December _ - 







1926 



January 







February 







March 







April 







May 



June 



July 



August... 



September 



October 



184 

 139 



98 

 95 

 281 

 253 



260 

 307 

 170 

 170 

 448 

 448 



1 No record. 



Station No. 6 is on the Mississippi River, about 3.5 miles below South St. Paul. 

 The important change to occur between stations 5 and 6 is the addition of the sewage 

 from South St. Paul, where packing plants are situated, and from a packing house 

 situated across the river, opposite South St. Paul. Grease occurred commonly on 

 the surface of the water when this station was visited. 



Station No. 7 is on the Mississippi River at Hastings, about 37 miles below St. 

 Paul. No sewage is added to the river between Hastings and station No. 6 at South 

 St. Paul, yet a very marked change in the condition of the river takes place. At 

 station No. 6 the water is relatively shallow and the current is fairly strong, so that 

 there is little chance for much of the solid material to settle out. At Hastings (station 

 No. 7) the current is rather slack, and consequently much of the solid material settles 

 on the bottom. The water is much deeper, too, and therefore is less effectively 

 aerated by winds. 



Station No. 8 is at Prescott, Wis., on the St. Croix River, just above the junction 

 of the St. Croix and the Mississippi Rivers. 



Station No. 9 is on the Mississippi River at Red Wing, about 50 miles below 

 St. Paul. By this time the river has received the waters of the St. Croix and the 

 Cannon Rivers. The discharge for these rivers is given in Table 2. 



