STREAM POLLUTION

By Hans Pederson, State Department of Health,

Des Moines, Iowa

By virtue of a stream pollution law enacted by the Iowa 40th General Assembly, practically all of the authority to control the utilization of the state streams is invested in the State Department of Health. For the first two years after the passage of this law only the most elementary studies and preliminary investigations were made for the reason that the department was sadly handicapped, due to lack of personnel and equipment. The 41st General Assembly corrected this condition to some extent and authorized a sum of $6,000 a year for 2 years to be used in the study of stream conservation and utilization.

As a result of this appropriation the State Department of Health is engaged at the present time in making a survey of the rivers and streams of the state, and a study of the cause and effect of stream pollution. Active field work commenced in the Iowa and Cedar Valleys on the 20th day of July, 1925, and will continue until sufficient data has been collected to solve the various problems now pending or until the appropriation is exhausted.

Two parties are engaged in making this study. One party consisting of two men is stationed in the upper portion of the Cedar Valley at Mason City and is collecting and testing samples of both river waters along the Lime Creek and Shell Rock River and wastes of several large industries located at Mason City. The second party, consisting of one man, started at the mouth of the Cedar River in Louisa County and is working north, visiting every community in the Cedar and Iowa Valleys, to locate all possible sources of pollution.

When the engineer making the survey enters a town he first. assures himself whether that community has a sanitary sewer system. If it has he next visits the outlet for the purpose of observing the method of disposal. The method of disposal is recorded on blanks furnished for that purpose, together with general information concerning the type and condition of the sewage treatment plant, if there is one, and the condition of the

stream into which the plant effluent or raw sewage is discharged. All industries, such as creamery companies, canning companies and slaughter houses are visited and the facts in regards to each recorded on special information blanks. Information concerning water supplies, garbage disposal and tourists camps are also collected during this survey as a matter of record.

The field laboratory work consists of collecting samples regularly from sampling stations along the rivers and making the dissolved oxygen tests. Dilutions are also made up of the raw and treated industrial wastes for the purpose of determining the 5-day biochemical oxygen demand.

As this study has hardly more than begun, it is not possible to state results at this time. The department's program as maped out is of such magnitude that it is impossible to say just when final results will be ready for publication. It is planned that as soon as the studies at each locality or district where conditions have become acute have been completed, a detailed report will be prepared covering the problem of that district. No results or conclusions will be published that are not backed up with thorough scientific study.

A number of the larger cities and industries of the state have been anxiously concerned with the activities of the State Department of Health regarding its studies of stream pollution. This feeling of anxiety or nervous inclination is not warranted as it is not the intention of the State Department of Health to inflict unnecessary or insane hardships upon any municipality or industry. The department is merely seeking facts upon which to base a sane utilization policy of the state's water resources. There is but one classification for Iowa rivers. Not a single drop of any river throughout its entire length can safely be used for drinking purposes without clarification and sterilization, and it would indeed be folly to even attempt to enforce a drastic control to bring about such a degree of purity as to eliminate treatment. On the other hand, there is not a single river in the state so badly polluted at this time but that the pollution can be economically controlled within certain limits. Iowa is primarily an agricultural state. There are but seven major industrial plants contributing objectionable wastes in large quantities, although there is a great number of minor industries, such as small creameries and canning companies, that contribute to the pollution. Only the cities along the larger rivers dis

charge domestic sewage direct and they are located so far apart that the wastes of one is apparently assimilated before it reaches another. All the rivers in Iowa should be placed in one class and controlled under the same general regulation.

The one big problem before the Department of Health is to work out a sane utilization policy. The people of the state who are interested in the outdoor life emphasize and insist that rivers be utilized for recreational purposes. That is, they wish the pollution to be controlled so that the water will support fish life and will not affect animal health and will be fit for bathing and boating. The industrial world naturally favors a policy which will permit them to dispose of their wastes at the least possible cost and have so far taken it for granted that disposal by dilution is their undisputed right. City Councils, as a rule, are only interested in the first cost of the necessary treatment plants to control the pollution, how the municipalities are to raise the money to pay for such improvements and what the taxpayers will say if they must undertake this expense.

A wise policy should not only be considered of all interests and opinions, but should seek the maximum benefit to the majority of the people. If it is definitely proven that a river cannot be used both for recreational purposes and a place to dispose of sewage and industrial wastes, then a decision must be made as to which use will be given preference. Wise control should recognize the natural power of stream to assimilate and dispose of organic matter and at the same time the general interests of the public through protection of public health, the health of animals and fish life, and all recreational pursuits.

This problem can only be worked out through co-operation. City officials should not seek to cover up the facts or let their own personal opinions overbalance public opinion. When the facts in each case are known, they should be presented to the public for a verdict. City Councils should not only desire to know the facts concerning the effect of the pollution of the river water by their city wastes, but should assist the State Department in every possible way to secure these facts. Industries should favor a thorough investigation because it is only through thorough investigations that they can hope to receive. unbiased treatment.

The State Department of Health is studying a problem that is far more complicated and difficult than the average person

realizes. Mental attitude and personal opinion should be based in every case on actual fact, but the verdict of the general public regarding the use to which any river can be put can no longer be overlooked. Public opinion is growing rapidly and is demanding the conservation of the state's water resources for future generations. It refuses to be downed and to be ignored. The cities of Iowa now disposing of sewage by dilution must sooner or later face the growing demand for control of pollution, and if everyone will begin now, in all seriousness to work out the financial problem, it would not be long before the conservation of the state's waterways in its truest sense will become a reality rather than a mythical hypothesis.

DISCUSSION

PRESIDENT-ELECT HATTON: Are there any questions anyone would like to ask, or any discussion of this paper?

MR. SHRIMER: Do I understand that he does chemical analysis only, or bacteriological?

MR. PEDERSEN: Only the chemical; purely the oxygen determination.

RELATION BETWEEN STREAM POLLUTION AND EX

TENT OF SEWAGE TREATMENT REQUIRED

By J. K. Hoskins, Sanitary Engineer, U. S. Public Health Service

The relation between stream pollution and the extent of sewage treatment must always be a flexible one because of the numerous variable factors involved. Perhaps among the most important of these factors are those of biological and biochemical changes, generally in the direction of improvement, which collectively may be termed "natural purification." Obviously the capacity of a stream for additional loading at any point must depend on the degree of purification of pollution previously received as well as on the ability to digest material added at the point under consideration.

Furthermore, the degree of permissible pollution is dependent among other things on the uses to which the water is to be put. Obviously a watercourse used as the source of a municipal water supply demands different consideration from one that needs only to be kept from becoming a nuisance to sight and smell. Between these wide limits, local requirements, such as the preservation of fish life, recreational uses and the like, will determine the limit of allowable pollution. The two extreme cases, that of public water supply and of nuisance prevention, may be briefly considered.

PROTECTION OF WATER SUPPLY

The degree of bacterial pollution, more specifically the B. coli content, has become the general criterion of the fitness of water supplies for drinking purposes, because this group of organisms is a most sensitive index of sewage pollution and at the same time is readily ascertained.

The criterion of permissible pollution in any stream used for water supply is then concerned with the numbers of this organism that may be expected to be contributed, the rate at which they are eliminated in the stream after they are added and finally the degree to which they may be removed by artificial water purification devices.