CONTENTS 



Page 



Introduction 1 



Sampling intragravel water for dissolved oxygen content 2 



Obtaining water samples from standpipes 2 



Analyzing water samples 4 



Reliability of samples 5 



Obtaining data on spatial differences and temporal changes 6 



Systematic sampling fc 



Temporal changes in dissolved oxygen content 7 



Daily 7 



Seasonal 8 



Yearly 8 



Spatial differences in dissolved oxygen levels 9 



Random sampling 9 



Routine evaluation of oxygen levels 10 



Summary 12 



Literature cited 13 



Appendix 14 



FIGURES 



1. Location of study streams, HoUis area, where dissolved oxygen levels reported in this 



paper were observed. Location of study area is shown by capital letters 3 



2. Method of placing standpipe in streambed for collection of water samples for deter- 



mination of dissolved oxygen content 4 



3. Apparatus for collecting water samples from standpipes 5 



4. Relationship between dissolved oxygen content of two 125-ml. water samples with- 



drawn less than 1 minute apart 6 



5. Mean dissolved oxygen values obtained at study areas in late August and early 



September of 1957 and 1958 9 



6. Dissolved oxygen levels at study area A (11 -foot tide level of Harris River). Samples 



were obtained 7 to 10 inches beneath gravel surface at points shown 10 



7. Dissolved oxygen levels at study area B (upstream Harris River). Samples were 



obtained 7 to 10 inches beneath gravel surface at points shown 10 



8. Dissolved oxygen levels at study area C (13-foot tide level of Indian Creek). Samples 



were obtained 7 to 10 inches beneath gravel surface at points shown 11 



9. Dissolved oxygen levels at study area D (17-foot tide level of Indian Creek). Samples 



were obtained 7 to 10 inches beneath gravel surface at points shown 11 



10. Dissolved oxygen levels at study area F (14-foot tide level of Twelvemile Creek). 



Samples were obtained 7 to 10 inches beneath gravel surface at points shown 12 



11. Dissolved oxygen levels at study area G (17-foot tide level of Twelvemile Creek). 



Samples were obtained 7 to 10 inches beneath gravel surface at points shown 12 



