# Water Quality Criteria

Report ofthe
National Technical Advisory Committee

to the Secretaryofthe Interior

APRIL 1, 1968 WASHINGTON, D.C.

FEDERAL WATER POLLUTION CONTROL ADMINISTRATIONable to survive lower salinities than can their predators and disease-causing organisms. Hence, in some tidal tributaries, oysters thrive in regions where they 

### arc sheltered from these pests by low salinity. Natural alterations in salinity distribution have been reportedly followed by increased mortality of oysters. It is clear that care must be exercised in the approval of engineering projects

or industrial processes that will alter salinity regimes in tidal tributaries and lagoons and in their associated wetlands. Salinity patterns can be caused to vary from "'normal" by alterations in character of freshwater inflow and basin geometry. These are the same factors that producechang es in circulation. Infact, salinity alterations are precursors to changes in density currents.
Recommendation: For the protection of estuarine

organisms, no changes in channels, in the basin geometry of the area, or in fresh water inflow should be made that would cause permanent changes in isohaline patterns of more than ± 10 percent of the natural variation. 

# Currents

Despite their large volumes, tidal waters, especially those in tributaries of the seas, have special circulatory characteristics that may affect their ability to assimilate wastes. For example, tidal action slows the already slowed (due to lowered slope and resulting reduced speed of gravity-induced flow) seaward movement of water in tidal rivers and streams

. This alternate up and down stream movement of the water in the freshwater portion of the tidal tributary is confounding enough in itself (Ketchum, 1950 and 1951;Stommcl
, 1 953a
, b) but in the estuarine reach, the area where sea salts are noticeable, further complexities often occur (Bowden, 1963; Hargis, 1965; Redfield, 1951 ). In horizontally and vertically stratified mixing estuaries, there are two streams. The upper stream, fresher and lighter, has a net

flow downstream while the lower stream, saltier

· and heavier
, flows inward or upstream. Since

these surface currents and bottom counter-currents often extend far to sea off the mouths of large tidal tributary orestuarine systems, aswell as farupstream, significant upstream transport ofmaterials in solution or suspension in the countercurrent can occur. These circulatory features are important in the life cycles of many estuarine species. Forexample, oyster and barnacle settingis related to tidal and nontidal currents (Barlow, 1955; Bousfield, 1955; Emery and Stevenson, 1957; Hargis, 1966; Ketchum, 1954; Pritchard, 1953). Large disturbances of current patterns can


### 68 disrupt the life cycles of estuarine organisms. Hence, projects that alter current patterns should becarefully evaluated andcontrolled. Itispossible to altercirculatorypatterns in tidal tributaries by ( 1 ) changing the quantity, timing, and location of fresh water inflow, (2) changing the geometry of the basin

. The former can be accomplished by constructionand operationofreservoirs above or below the 

### fall line (defined as the uppermost limit of ocean's tidal activity). The latter can be accomplished by shoreline orbottom modification; e.g., drainage, bulkheading and filling, channel dredging, and subaqueous spoil disposal or mining. Oyster harvesting practices have been known to produce marked changes in bottomgeometry (Hargis, 1966)

. Recommendation: In view of the requirements of

estuarine organisms and the nature of marine waters, no changes in basin geometry or fresh water inflow should be made in tidal tributaries which will alter current patterns in such a way ns to cause adverse effects. 

# pH

Despite the great emphasis given to the importance of pH in the literature, little is known of its direct physiological effects on marine organisms. Its indirect effects, however, are extremely significant. Even a slight change in pH indicates that the buffering system inherent in seawaterhas been altered radically and that either a potential or actual carbon dioxide imbalance exists. This im

balance can be deleterious or disastrous to marine life. A second indirect effect is that pH can influence the toxicity ofothermaterials. Cyanide and ammonia, discussed under "Toxicity," are outstandingexamplesofthis kind ofaction.
Recommendation: Materials that extend normal ranges

of pH at any location by more than ± 0.1 pH unit should not be int1'oduced into snit water portions of tidal tributaries or coastal waters. At no time should the introduction of foreign materials cause the pH to be less than 6

.7 or greater than 8.5. 

# Temperature

Temperature requirements of marine and estuarine organisms in the biota of a given region may vary widely. Therefore, if we arc to maintain temperature favorable to the biota, all important species, including the most sensitive, must be protected. It has been found that organisms in the intertidal zone vary considerably in their ability to withstand high temperatures. Those in the uppermost areas of the tidal zone generally can with-



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: upNithstand higher temperatures than those in the lower portions of the tidal zone and these in tum generally can withstand higher temperatures than the

same species of animals living in the subtidal

zones. In addition, when considering the coastline
as a whole, we must recognize that there are vari

ous races within a given species. which may vary considerably in their environmental requirements,

or in their ability to withstand extreme conditions. In our marine waters, there is a great mixture of species. Species typical of higher latitudes are found with species that are more abundant farther south. Tropical or subtropical species generally will spawnin the summer months. Speciesfrom the higher latitudes require low water temperature for spawning and the development oftheyoung. Thus, they usually spawn in the winter months and temperatures at that time are critical. Any warmingof the wat er during the cold weather or winter period could be disastrous from the standpoint ofthe elimination of the more northerly species. In some instances, a rise in winter temperatures of only 2

or 

### 3 F mightbe sufficient to prevent spawning and thus eliminate these specie$ from the biota

. In the northern portions of the country there is generally a great range in natural temperatures. In southern areas, as we approach the tropics, we find smaller overall temperature ranges. In the tropics

or subtropics, optimum temperatures for many forms arc only a few degrees lower than maximum lethal temperatures

. Great care should be exercised, therefore, to prevent harmful increases in maximum summer temperatures in tropical areas. In general, temperatures in the marine waters do not change as rapidly nor do they have the overall range from extreme to extreme as they do in fresh waters. Marine and estuarine fishes, therefore, are less tolerant of temperature variation

. They can accommodate somewhat, but overall temperature range and rate of change arc even
more important here than they are in fresh waters

. It has been observed that when surface water temperatures over the Georges Bank increased from 46 to 68 F, the larval fish died at 65 F. It has been found that species in subtropical and tropical en

vironments are living at temperatures that areonly

a few degrees less than their lethal temperatures

. In the most northern forms, extensive variations inseasonal temperatures are a necessity for orderly development and growth. Spawning and development frequently occur at lower temperatures and the sexual products ripen on rising temperatures after a period of low temperatures. Temperatures above or below the optimum range may delay or speed up development. They may inhibit swimming ability and the effectiveness of food utilization may be decreased with increasing temperatures in the upper viable range. Fishes and other forms are also more susceptible to parasites and diseases at temperatures outside of their optimum range. In regard to rapid changes in temperature, it has been found that a drop in temperature from 58 to 43 F kills sardines. Tolerable temperature minima vary with the population and its past temperature history. Kills have occurred off the Texas coast at 

### 40 F whereas kills of the same species have occurred off Bermuda at a drop to 

### 59 F. Many kills have occurred 

### in nature due to unusu

ally low temperatures

. Kills also occur due to natural high temperatures. Yellowtail flounder and whiting larvaedied when they drifted from an area of 44 F to one of 64 F. It has been reported that 

### 61 F is best for the developing of mackerel, but 

### 70 F is too high. These are merely illustrations of what might happen to species occurring in inshore waters. , It is apparent from the foregoing that data are very sparse on temperature requirements ofmarine and estuarine species. It is very difficult, therefore, to attempt to suggest temperature requirements for marine and estuarine forms. The difficulty is compounded by the great extent of the Nation's shorelines, the differing natural temperature variations from north to south, and the geographicoverlapping of species native to different latitudes. Consideration must be given to maximum allow

able temperatures forboth the summer period and the winterperiod. In attempting to establish permissible levels of temperature increase in receiving waters due to heated waste discharges, precaution must be tak

· en to prevent- (a) excessive incremental increases above background values even though such incremental increases lie below maximum limits, and (b) exceeding maximum natural background limits.. Such precautions are necessary to prevent gradual net increases in background temperatures due to the continuously increasing volumes of heated wastes beingdischarged into receiving waters. The discharge of heated wastes into estuaries and other tidal tributaries mustbe managed sothat

no barrier to the movement or migration of fish and other aquaticlife iscreated.

Recommendation: In view of the requirements lfor

the well-being and production of marine organisms, it is concluded that the discharge of any heated waste into any coastal or estuarine waters should be closely managed. Monthly means of the maximum daily tem

peratures recorded at the site in question and before


### 69the addition of any heat of artificial origin should not be raised by more than4 F during the fall, winter, and spring (September through May), or by more than 1.5F during the summer (June through August). North of Long Island and in the waters of the Pacific Northwest (north of California), summer limits apply July through September, and fall, winter, and spring limits apply October through June. The rate of temperature change should not exceed 1 F perhour except when due to natural phenomena.

Suggested temperatures are to prevail outside of established mixing zones as discussed in the section on zones ofpassage. 

# Dissolved oxygen

Dissolved oxygen requirements of marine organisms arenotaswell knownasthosefor freshwater forms. Studies have been made indicating that minimum dissolved oxygen concentrations of 

### 0.75 to 

### 2.5 a(e required for test species to resist death for 24 hours. Most marine species died when the dissolved oxygen dropped below 

### 1.25 mg/ 1for a few hours. Reduced swimming speed and· changes in blood and serum constituents occurred at dissolved oxygen levels of 

### 2.5 to 

### 3 mg/1. It was found thatDOlevelsbetween5.3 and 8 mg/ 1were satisfactory for survival and growth. Levels above 17mg/1
, however, produced adverse effects. Large fluctuations in dissolved oxygen from 3 to 8 mg/1, diurnal or otherwise, produced significantly more physiological stressin fishes thanfluctuations from 3 to 6 mg/1. In tests made to date, it has been found that 5 to 8 mg/1 of DO is apparently sufficient for all species of fish for good growth and general well being. It is generally recognized that in deeperwaters DO values are often considerably less than 5.0 mg/ 1. In estuaries where there is a reduction in salinity, levels may drop to as low as 4 mg/1 at infrequent intervals and for limited periods of time. It is probable that many marine animals can live for long periods of time at much lower levels of DO. Experimental studies with freshwater organisms

.have demonstrated, however that lowconcentrations ofDO atwhichadult fish;s can live almost indefinitely, can inhibitfeeding and growth. In determining DO requirements, it is essential to consider growth, reproduction, andothernecessary life activities.
Recommendation: For the protection of marine rc·

sources, it is essential that oxygen levels shall be sufficient for survival, growth, reproduction, the general well-being, and the production of a suitable crop. To attain this objective, it is recommended that dissolved oxygen concentrations in coastal waters, estuaries, and tidal tributaries of the Nation, including Puerto Rico, Alaska andHawaii, should be as follows: ( 1) Surface dissolved oxygen concentrations in


### 70 coastal waters shall not be less than S.O mg/1, except when natural phenomena cause this value to be depressed.

(2) Dissolved oxygen concentrations in estuaries and tidal tributaries shall not be less than 4.0 mg/1 at any time or place except in dystrophic waters or where natural conditions ca\!se this value to be depressed.

The committee would like to stress the fact that, due to a lack of fundamental information on the DO requirements of marine and estuarine organisms, these requirements arc tentative and should be changed when additional data indicate that they are inadequate. 

# Crude oil and petroleum products

The discharge of crude oil and petroleum products into estuarine and coastalwaters presents special problems in water pollution abatement. Oils from different sources have highly diverse propertics and chemistry. Oils are relatively insoluble in

sea and brackish waters and surface action spreads the oil in thin surface films of variable thickness, depending on the amount of oil present. Oil, when adsorbed on clay and other particles suspended in the water, forms large, heavy aggregates that sink to the bottom. Additional complications arise from the formation of emu lsions in water, leaching of water soluble fractions, and coating and tainting of sedentary animals, rocks, and tidal flats. Principal sources of oil pollution are numerous. Listed in order of their destructiveness to ecosystems, they are: ( 1 ) Sudden and uncontrolled discharge from

. wells towards the end of drilling operation. (2) Escape from wrecked and submerged oil tankers. (3) Spillage of oil during loading and unload

ing operations, leaky barges, and accidents duringtransport. · (4) Discharge of oil-contaminated ballast and bilge water into coastal areas and on the high seas. (5) Cleaning and flushing of oil tanks at sea. On the average, 

### a ship's content of such wastes is estimated to contain 2 to 3 percent oil in 1,000 to 2,000 tons of waste. (6) Spillage from various shore installations, refineries, railroads, city dumps, garages, and various industrialplants. 

# Spillage From Wrecked Oil Tankers

Even though wrecks of oil tankers along the Atlantic coast and subsequent spillage of oil into the sea have been reported severa l times, no thor-



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