Cairns (1957) reports the following 96-hour TL,„ 

 values of naphthenic acid for bluegill sunfish 

 (Lepomis inacrochirus) — 5.6 mg/1; pulmonate 

 snail (Physa heterostropha) — 6.1 to 7.5 mg/1 (in 

 soft water), and diatom (species not identified) — 

 41.8 to 43.4 mg/1 in soft water and 28.2 to 79.8 

 mg/I in hard water. Naphthenic acid (cyclohexane 

 carboxylic acid) is extracted from petroleum and 

 is used in the manufacture of insecticides, paper, 

 and rubber. 



Chipman and Galtsoff (1949) report that crude 

 oil in concentrations as low as 0.3 mg/1 is ex- 

 tremely toxic to fresh water fish. Dorris, Gould, 

 and Jenkins (1960) made an intensive study of the 

 toxicity of oil refinery effluents to fathead minnows 

 in Oklahoma. By standard bioassay procedures, 

 they found that mortality varied between 3.1 per- 

 cent to 21.5 percent after 48 hours of exposure to 

 untreated effluents. They concluded that toxicity 

 rather than oxygen demand is the most important 

 effect of oil refinery effluents on receiving streams. 



Pickering and Henderson (1966b) reported the 

 results of acute toxicity studies of several impor- 

 tant petrochemicals to fathead minnows, bluegills, 

 goldfish, and guppies in both soft water and hard 

 water. Standard bioassay methods were used. Be- 

 cause several of the compounds tested have low 

 solubility in water, stock solutions were prepared 

 by blending the calculated concentrations into 500 

 ml of water before addition to the test container. 

 Where necessary, pure oxygen was supplied by 

 bubbling at a slow rate. The petrochemicals tested 

 were benzene, chlorobenzene, 0-chlorophenol, 3- 

 chloropropene, 0-cresol, cyclohexane, ethyl ben- 

 zene, isoprene, methyl methacrylate, phenol, 0- 

 phthalic anhydride, styrene, toluene, vinyl acetate, 

 and xylene. These petrochemicals are similar in 

 their toxicities to fish, with 96-hour TL,,, values 

 ranging from 12 to 368 mg/1. Except for isoprene 

 and methyl methacrylate, which are less toxic, 

 values for all four species of fish for the other 

 petrochemicals ranged from 12 to 97 mg/1, a rela- 

 tively small variation. In general, 0-chlorophenol 

 and 0-cresol are the most toxic and methyl meth- 

 acrylate and isoprene are the least toxic. 



Recommendation: In view of available data, it is con- 

 cluded that to provide suitable conditions for aquatic 

 life, oil and petrochemicals should not be added in 

 such quantities to the receiving waters that they will: 

 (1) produce a visible color film on the surface, (2) 

 impart an oily odor to water or an oily taste to fish 

 and edible invertebrates, (3) coat the banks and bot- 

 tom of the water course or taint any of the associated 

 biota, or (4) become effective toxicants according to 

 the criteria recommended in the "Toxicity" section. 



Turbidity 



Turbidity is caused by the presence of suspended 

 matter such as clay, silt, finely divided organic 

 matter, bacteria, plankton, and other microscopic 

 oragnisms. Turbidity is an expression of the optical 

 property of a sample of water which causes light to 

 be scattered and absorbed rather than transmitted 

 in straight lines through the sample. Excessive 

 turbidity reduces light penetration into the water 

 and, therefore, reduces photosynthesis by phyto- 

 plankton organisms, attached algae, and sub- 

 mersed vegetation. 



The Jackson candle turbidimeter (Standard 

 Methods for the Examination of Water and Waste- 

 water, 12th edition. 1965) is the standard instru- 

 ment for making measurements of turbidity. Field 

 determinations, however, are made with direct- 

 reading colorimeters calibrated for this test and the 

 results are expressed as Jackson turbidity units 

 (JTU). 



Silt and sediment are particularly damaging to 

 gravel and rubble-type bottoms. The sediment fills 

 the interstices between gravel and stones, thereby 

 eliminating the spawning grounds of fish and the 

 habitat of many aquatic insects and other inverte- 

 brate animals such as mollusks, crayfish, fresh 

 water shrimp, etc. Tarzwell (1957) observed that 

 bottom organisms from a silted area averaged only 

 36 organisms/sq ft compared to 249/sq ft in a 

 non-silted area. Smith (1940) reported that silting 

 reduced the bottom fauna of the Rogue River by 

 25 to 50 percent. Observations in Oregon by Wag- 

 ner (1959) and Ziebell (1960) showed an 85- 

 percent decline in productivity of aquatic insect 

 populations below a gravel dragline operation. 

 Turbidities in the affected area were increased 

 from zero to 91 mg/1 and suspended solids from 

 2 mg/1 upstream to 103 mg/1 downstream. 

 . Buck (1956) investigated several farm ponds, 

 hatchery ponds, and reservoirs over a 2-year 

 period. He observed that the maximum production 

 of 161.5 lb/acre occurred in farm ponds where 

 the average turbidity was less than 25 JTU. Be- 

 tween 25 and 100 JTU, fish yield dropped 41.7 

 percent to 94 lb/acre, and in muddy ponds, where 

 turbidity exceeded 100 JTU, the yield was only 

 29.3 lb/acre or 18.2 percent of clear ponds. 



Herbert and Merkens (1961), using a mixture 

 of kaolin and diatomaceous earth, demonstrated 

 that long-term exposure of rainbow trout to 100- 

 200 mg/1 could be harmful. At 270 and 810 mg/1, 

 a high percentage of the fish died. Wallen ( 1951 ) 

 studied the effects of montmorillonite clay on 16 

 species of warm-water fish. Results are shown in 

 table III-2. It is shown that fish can tolerate high 



46 



