Figure l,--Location of study streams. Mollis area, where dissolved oxygen levels reported in this paper were 

 observed. Location of study areas is shown by capital letters. 



again by removing the lower 3 inches and 

 drilling new holes. Driving rods manufactured 

 from high-quality steel withstood at least 1,000 

 drives. 



Driving rods 36, 33, and 30 inches long were 

 used. Standpipes were initially cut to fit the 

 longest driving rod, and they were subse- 

 quently shortened to 33 and 30 inches, re- 

 spectively, as their lower edges became dam- 

 aged. 



Water samples were sucked from standpipes 

 with an apparatus constructed of tubing and 

 a two-holed. No. 4 rubber stopper, and col- 

 lected in 8-dram shell vials. Stoppers for 

 the vials were one -holed. No. 3 rubber stoppers 

 with a short piece of 6 -mm. glass tubing 

 inserted. Each component of the water sam- 



pling apparatus is illustrated in figure 3. 

 Harper (1953) describes similar equipment. 



To obtain a sample, the suction apparatus 

 is connected to a vial. The glass tubing 

 through which ^water enters the vial must ex- 

 tend nearly to the bottom. The suction line 

 is inserted into a standpipe, and water is sucked 

 from near the bottom of the well. About 10 

 cc. of water is discarded before the sample 

 is collected. The suction line is pinched off 

 before discarding the first 10 cc. of water, 

 preventing the suction line from becoming 

 drained and reducing contact of the water 

 surface with the atmosphere. As the stopper 

 is placed after collecting a sample, a column 

 of water is allowed to rise about halfway 

 up the glass tube in the stopper. Chemicals 

 used to fix the water sample are introduced 



