preliminary sedimentation is possible, but for just how long a period, with increasing population, the canal could continue to complete the work of oxidation of settled sewage and not be overtaxed so as to become itself a sewer can not be determined. The limits are probably between the present population and double that number. Further treatment of organic matter other than by sedimentation involves oxidation upon filters or by some similar process, and under local conditions would be almost prohibitively expensive.

Bacteriologically, there would be some gain in the canal project over the river discharge. The river does not permit sedimentation, and its high velocity carries the sewage bacteria to the lower lake in practically undiminished numbers. In the canal the number of bacteria surviving the passage to the lake would be diminished in the 17 hours' interval, both by sedimentation and by natural decrease. This advantage would be largely offset, however, by the greater concentration of sewage in the canal waters, which would be in the ratio of the river discharge, 210,000 secondfeet, to the canal discharge, 6,000 second-feet, or thirtyfivefold. The waters of the canal and of the end of Lake Ontario adjacent to and within an undetermined radius of its outlet would be polluted to nine times as great an extent as the Niagara at present, even after allowing for a 75 per cent decrease in bacteria en route, a maximum estimate. This condition must obviously be met with some form of disinfection treatment, for even though it have no international aspect, an assumption not wholly justified, it assuredly would not be an "advisable" plan in the sense of the reference, unless it could compare in net results accomplished with other plans presented.

To place any canal project upon an equal basis of merit with the plans outlined for treatment and discharge into the Niagara, a minimum treatment equivalent to sedimentation and disinfection of the sewage before discharge into the canal must be added, with no assurance that the result would then be satisfactory.

CONCLUSION REGARDING THE DRAINAGE CANAL PROJECT.

This consideration of a drainage canal project, therefore, leads to the conclusion that such a canal if constructed would present no advantages over the Niagara River as a means of sewage disposal, and that the cities of the Niagara frontier, located upon one of the greatest rivers of the country, need no additional water facilities for the disposal of their sewage by dilution methods. Such incidental purification as is called for in connection with the utilization of the resources of this stream represents the minimum of requirements for any dilution system, and dilution in any smaller volume of water will call for more

intensive treatment for an equal degree of protection of health and property.

SUMMARY OF ENGINEERING INVESTIGATION.

TYPE OF TREATMENT.

The general type of treatment adopted, with suitable local modification, is therefore essentially the same in all cases. It comprises coarse screening for the removal of large floating material, sedimentation in Imhoff tanks, with simultaneous chemical disinfection with chloride of lime. The necessary auxiliary plant, sludge drying beds, chemical mixing tanks, etc., are also provided.

COSTS.

The estimated costs of construction have been treated in the usual manner as invested capital against which an annual charge for depreciation based upon an assumed life (sinking-fund allowance) and an interest charge have been made. This annual charge has been increased by the estimated annual operating expenses to give a total annual expense, and this in turn has been reduced to a per capita basis for purposes of comparison. These figures are set forth in detail in the reports which follow. They are summarized in Tables VIII, IX, and X.

The weighted average annual charge for the entire population of the Detroit district is found to be $0.57, for the Buffalo district $0.68, and for the two combined $0.61 per capita per annum. For comparison with this figure it will be of interest and value to determine the total charge for water supply and sewerage in certain cities. Sewage disposal is properly to be regarded as the final step in a complete system which begins with the collection, purification, and distribution of the water supply, includes the collection of domestic and industrial sewage, and ends with the disposal of the sewage. Without water supply there would be no sewage and with water supply, sewers and final disposal are essential. The system, regarded as a whole, is necessary to the well-being of the community; the proper disposal of the final product is a necessary part of the system, and its cost a part of what the community must pay for the benefits of water and sewerage. The statistics of the United States Census Bureau are available for the purpose of this comparison. There are there given the present value and

1U. S. Census Bureau, Financial Statistics of Cities, 1912. Washington, D. C., 1913.

In comparison with these costs, which are fairly representative, and, because of their number, subject to less error than those of individual cities, the cost of sewage disposal as a part of this total cost of water and sewerage does not appear to be an unreasonable or disproportionate amount.

CONCLUSIONS AS TO REMEDIES.

Application of the criterion of effective dilution to the case of the Detroit and Niagara Rivers has been shown to lead to a certain specified degree of sewage treatment in the two cases. The costs of the required remedial measures have been determined and found to be reasonable in view of the results to be attained, and not disproportionate in view of the general costs of water and sewerage works in American cities. The application of these measures upon these two streams is therefore recommended as both "possible" and "advisable" in the terms of the reference.

Similar studies of cost were also made in the case of the St. Clair River communities upon the same basis of the requirements.

The criterion of effective dilution must also be applied to this and the other boundary rivers to determine what, if any, sewage treatment is required in each case. It is readily seen that except in the case of the Detroit and Niagara Rivers no further treatment is at present required to satisfy the general international requirements as here laid down. The application of the measures outlined for the St. Clair River, for example, which is the next most seriously polluted stream, is not justified by the evidence of transbound

ary effect, this stream being in a better condition than that to which it is feasible to bring the Detroit and Niagara Rivers by present-day methods of sewage treatment. This conclusion, however, is of a general nature and must be modified according to each local situation. There must be considered, first, the conclusion of the advisory engineers, that a minimum requirement for discharge of sewage into these waters should be the removal of gross floating material by coarse screens. Treatment to this extent is indicated wholly upon the grounds of the immediate local effect of sewage discharge in a purely esthetic way. In addition to this minimum requirement, there is also to be considered the proximity of near-by waterworks intakes and the question of so dispersing the sewage throughout the volume of the stream that not only the average conditions may comply with a reasonable criterion of purity, but that the concentration of sewage at any one point or in any one line of flow shall not be excessive. On the other hand, local conditions may determine that concentration of sewage near the shore and location of waterworks intakes in the center of the stream represents the most economic solution. These are matters which are primarily of local interest and need not, in the first instance at least, come under the general administrative control over these boundary waters from an international standpoint.

In the development of a systematic policy of stream protection, however, it may very well appear that the future requirement of the situation may be best met by bringing the entire control of stream pollution under one administrative organization. Whatever may be the solution of this matter in the case of those streams which are not at present so polluted as to demand remedial treatment under the terms of the treaty, it is evident that the organization responsible for carrying out this work in general must also be responsible for the making of routine observations upon all the boundary waters with sufficient frequency to permit the establishment of the facts of pollution and of its extent with increasing population, and to indicate the future need of remedial requirements sufficiently in advance of their actual necessity to permit proper engineering studies and the construction of the necessary works. In this sense, therefore, the jurisdiction of whatever administrative body may be appointed to take charge of this work should be coextensive with the entire system of boundary waters. In the case of the St. Clair River, the detailed engineering studies already alluded to have been made with the same degree of care as has been employed upon the more seriously polluted rivers, although, judged solely from the terms of the reference, the application of general remedies is not called for at the present time. These studies, however, have been

made to serve a twofold purpose. In the first place the relation of sewage disposal to water supply on either side of the river is one demanding some definite and immediate local consideration, independent of any international questions involved. These lead necessarily to minimum requirements of treatment and can not reduce the local requirements, which are in general more exacting. In the second place, this river probably will be the first of the remaining streams to fall within the limits of effective dilution, and the studies that have been made will serve to point out the requirements of the future toward which drainage studies and allied problems should be directed. Studies of this character are needed and should be made in the near future in the case of all of the other communities upon the boundary rivers. It is worthy of suggestion that in the interest of economy and uniformity of administration, studies along these lines. might well be continued by the International Joint Commission or by the administrative organization appointed to deal with this matter. In this way the problems of the future will be more definitely brought to the notice of these communities and their general solution will be better correlated along similar lines. POLLUTION BY STEAMBOATS-GARBAGE.

Some attention was given in the Progress Report to the matter of steamboat pollution of the boundary waters. This was shown to be a distinct source of pollution to be reckoned with in certain sections. This matter was also dealt with at the conference with the consulting sanitary engineers and their recommendations regarding it have already been quoted. In view of the character of this pollution, steamboats must be looked upon as moving sewer outlets traveling over the boundary waters and necessarily passing at times. by and in close proximity to waterworks intakes. While the total contributing population is not great compared with the populations dealt with in the case of the cities, the peculiar conditions under which this pollution is discharged make it highly desirable, if feasible, to deal with this problem. Investigations conducted by the United States Public Health Service at the Hygienic Laboratory, Washington, D. C., have shown the entire feasibility and practicability of thoroughly disinfecting the discharge from steamboats by means of live steam. The apparatus required for this purpose is inexpensive and does not require an undue amount of space. The entire cost of installation and operation of such a disinfecting system is such that it can be borne without difficulty by the owners of steamboats and the placing of this additional responsibility upon these owners is entirely justified by the benefits which will result. The importance of this aspect of the pollution problem is sufficient to justify the appli cation of remedial measures in this case pending the

adoption of more general measures on the part of the cities. Even under existing conditions the lessened danger to the water supplies of the steamboats themselves, as well as to those municipal supplies which are at present affected only by steamboat pollution, will justify the immediate adoption of these measures.

In the case of one American community, the city garbage and other refuse matter is dumped into one of the main outfall sewers, through which it passes directly to the river front. This material is not only unsightly in the immediate vicinity, but by reason of its gross character it serves to pollute the waters with undesirable organic material the evidences of which persist for many miles. Such a practice is obviously improper and unnecessary and should be specifically prohibited in any regulations governing the pollution of boundary waters.

CONSTRUCTION AND MAINTENANCE OF WORKS.

MEANS FOR SECURING CONSTRUCTION.

The reference further calls for recommendations as to

by what means or arrangement can the proper construction or operation of remedial or preventive works or a system or method of rendering these waters sanitary and suitable for domestic and other uses be best secured and maintained in order to secure the proper protection and development of all interests involved

The reference to means for securing the proper construction of remedial works, if it be not a duplication of the earlier reference to a 66 way or manner" to remedy or prevent existing pollution, must deal with the necessary legal machinery, or procedure, for carrying into effect the "way or manner" found "possible and advisable." It is not therefore an engineering question and its discussion will not be undertaken at this point.

MAINTENANCE AND OPERATION OF WORKS.

The further reference to maintaining the operation of the remedial works and to the protection and development of all interests involved evidently looks to the future administration of the matters dealt with. Such administration involves engineering and administration features in addition to the legal and legislative and the former will be treated here.

The procedure and experience of the Provinces and States which have dealt with stream pollution in an effective administrative manner may be taken as a guide in this matter. Proper administrative control of stream pollution must be based upon laws so carefully drawn as regards their reasonableness and their consideration of common-law rights as to stand the test of the courts. These laws receive their support in

the police power of States to abate nuisances and to protect property and the public health.

The enforcement of the law demands an organization equipped with facilities for engineering and laboratory examinations and investigations and with a staff versed in the principles of public health, sanitary engineering, chemistry, and bacteriology. The particular case under discussion will necessitate an organization of this kind and of considerable size. Its duties will refer largely to the protection of the public health, and in order to prevent duplication of effort and equipment the existing public health organiza tion of the two Governments should be utilized as far as possible. To this end the following is tentatively submitted. A board to be composed of the Surgeon General of the United States Public Health Service and of the Director General of Public Health of Canada might well constitute the head of the administrative organization, utilizing the present quarters and equipment of the marine hospitals in the United States and of any similar facilities in Canada. Following precedents already established by the International Joint Commission, this board might be authorized to formulate rules and regulations for carrying out the recommendations and policies of the commission, such rules as well as any matters upon which the board may not be in agreement to be submitted to the commission for approval or decision.

GUIDING PRINCIPLES IN CONTROL OF POLLUTION.

The following general principles should guide in the formulation of regulations for the control of pollution in the boundary waters in its international aspects:

1. The boundary waters shall not be polluted on either side to the injury of health or property upon the

other.

2. In the case of the boundary rivers the interests of the two countries are so closely bound together as to be mutual and the quality of the streams as a whole shall be considered in determining upon limits of permissible pollution.

3. The limit of permissible bacterial pollution shall be deemed to have been exceeded when the effective dilution as hereinafter defined shall be less than 4 cubic feet per second per capita of contributing population, based upon mean river stages during the season May to September, inclusive.

4. The effective dilution shall be taken as the quotient of the actual physical dilution divided by the residual fraction of the total bacteria remaining after treatment, provided that in the case of the St. Lawrence and other rivers where the time element is such as to permit some degree of self-purification between. points of successive pollution, this factor shall be con

sidered as an element of treatment entering the determination of effective dilution at the lower point.

5. In all cases where the actual stream flow below any one point of pollution is less than 4 cubic feet per second per capita of contributing population, or where the net effect of successive pollution with proper allowance for self-purification in the intermediate stretches exceeds the equivalent of one contributing person per 4 cubic feet per second of stream flow, sewage treatment shall be employed to reduce the net bacterial pollution to a basis of an effective dilution of 4 secondfeet per capita, as defined.

6. Sewage treatment, while based primarily upon bacterial pollution, shall also include the removal of suspended solids capable of settling to approximately the same degree as is called for in the case of bacteria; provided that this requirement shall not be extended to an unreasonable degree in the light of good engineering practice; and provided further, that in the case of combined sewer systems, ordinary mineral detritus shall be excluded in computing the degree of removal. 7. In all cases where sewage treatment to a specified degree is demanded, the entire contributory popula

tion shall be dealt with upon the same basis of relative improvemnt required, so that the net residual pollution from each community shall be proportional to its population; provided, however, that where the factor of self-purification is an element in the degree of pollution at any point the population above shall be reduced to equivalent population at that point by the self-purification factor, and the burden of responsibility shall be apportioned in terms of these equivalent populations.

8. Steamboats which pass by waterworks intakes shall be regarded as being capable of discharging sew. age in the near vicinity of those intakes without appreciable dilution. The application of the rule leads in this case to a complete bacterial purification or sterilization before discharge. Equivalent removal of solids capable of settling will not be required in the case of steamboats.

9. No garbage, city waste, offal, or other like material capable of polluting or rendering offensive the waters shall be deposited in the boundary rivers, or in such places as will permit their reaching these rivers.