ous municipalities. The actions of these boards, in carrying out the general pollution laws, are to a large extent independent of the Ministry of Health in London, which was recently formed to take over the functions of the Local Government Board; but in the case of such matters as bond issues or legal action against a manufacturer the consent of the Ministry of Health must previously be obtained. The Royal Commission, in its third report, 1903, states that these. rivers boards are of much greater value for the protection of rivers and streams than the separate councils acting independently, and that, although some of those against whom action has been taken by these boards have complained, as might be expected, generally speaking both the local authorities and the manufacturers recognize that in this way effective action is taken for the improvement of the rivers in their districts. The evidence before the Royal Commission on Sewage Disposal shows that these boards have accomplished much useful work in cleaning up the rivers.

In Germany there are various river or drainage districts among which the Emscher District in the industrial area of western Germany is a noteworthy example. The control of stream pollution was vested by the government in a board of more than 100 members representing the state, county, city, farm, mine and industrial interests, the actual work being carried on by a Board of Directors of ten in number. For further discussion of these boards the reader is referred to the report of the Committee.

Legislation

Numerous bills relating to the pollution of navigable streams by oil, acid wastes, including mine drainage, or other wastes, were introduced in Congress last year. Of these the so-called "Oil Pollution Act, 1924" became law on June 7, 1924. This Act provides that, except in certain cases of accident or emergency, or as permitted by regulations which the Secretary of War is authorized to prescribe, it shall be unlawful to discharge oil into or upon the coastal, navigable waters of the United States from any oil-burning or oiltransporting vessel.

The penalty for violation of this Act is a fine not exceeding $2500 nor less than $500, or by imprisonement not exceeding one year nor less than thirty days, or by both such fine and imprisonment, for each offense. Clearance of such vessel from a port of the United

States may be withheld until the penalty is paid, and said penalty shall constitute a lien on the vessel. Provision is also made for revoking the license of the officer of the vessel.

For the administration of the Act, the Secretary of War is authorized to make use of the organization, equipment and agencies employed in the improvement of rivers and harbors, and the officers and agents in charge of such improvements, and the assistant engineers and inspectors employed by them; and the officers of the Cutoms and Coast Guard Service are charged with the arrest of violators of the provision of the Act.

The Act also provides as follows:

SEC. 9. That the Secretary is authorized and directed to make such investigation as may be necessary to ascertain what polluting substances are being deposited into the navigable waters of the United States, or into nonnavigable waters connecting with navigable waters, to such an extent as to endanger or interfere with navigation or commerce upon such navigable waters or the fisheries therein; and with a view to ascertaining the sources of such pollutions and by what means they are deposited: and the Secretary shall report the results of this investigation to the Congress not later than two years after the passage of this Act, together with such recommendations for remedial legislation as he deems advisable.

For this investigation the sum of $50,000 is authorized in addition to funds already appropriated for examinations, surveys and contingencies of rivers and harbors, which may be drawn upon.

This Act is "Public-No. 238-68th Congress (S.1942)," and copies may be obtained from members of Congress.

Need of sound legislation

State legislation is needed in some states, to control adequately industrial wastes pollution within these states. National legislation is needed to control pollution of interstate and coastal waters. Such legislation, whether state or national, must be considered from the broad viewpoint of public welfare. It should be based on the results of thorough investigation. The importance of securing the cooperation of all interested parties must not be overlooked.

CHAPTER IV

GROUND WATER

Ground water is the accumulation of water in the pores and crevices of the ground. Its primary source is rainfall which enters by percolation through surface material. The upper limit of water in the ground is termed the "water-table." All water entering the ground and not taken up by vegetation must after a certain penetration, (1) escape laterally to some ultimate outlet, at lower elevation, in spring, stream, lake or ocean, or (2) add to the storage in the ground and raise the water-table. Free lateral flow takes place only through deposits or strata of relatively permeable materials, such as sandstone, sand, gravel, decomposed rock or fissured limestone. All ground water supplies are taken from some such formation.

Form of water-table

The water-table is analagous to the flow line of a surface stream, in that its profile depends upon the hydraulic slope necessary to produce flow. At the margins of streams the surface water level and the ground water-table coincide. Passing back from streams the water-table rises, the gradient varying with the resistance to flow and the quantity of water flowing. Increased percolation raises and steepens the water-table and increases the flow laterally, the amount of rise being least at the outlet and most at some interior point.

Percolation

The amount of water that may enter the ground in a given locality is dependent mainly upon four factors, namely:

a. Amount of rainfall

b. Facilities for quick run-off of rainfall into adjacent surface streams

c. Permeability of surface material

d. Capacity of the underlying material for carrying the water away laterally

In the case of extensive, deep-seated water-bearing formations, the carrying capacity of the formation usually limits the amount of

water that may enter it. The percentage of rainfall actually supplied by the catchment areas of water-bearing formations probably does not exceed 60 in the most favorable cases and may be less than 1, depending on the factors above mentioned.

Porosity

The porosity of a soil, or ratio of interstices to total bulk is a measure of the space that may be taken up by water. It is dependent upon the compactness of the material and the gradation in size of its particles. Porosities of common soil materials are as follows: Sands and gravels of fairly uniform size and moderate compactness, 35 to 40 per cent; well graded compacted sands and gravels, 25 to 30 per cent; sandstones, 4 to 30 per cent; chalk, 40 to 60 per cent; granite, schist, and gneiss, 0.02 to 2 per cent; slate and shale, 0.5 to 8 per cent; limestone, 0.5 to 14 per cent; clay, 44 to 47 per cent; top-soils, 45 to 65 per cent.

The factors essential to free flow in water-bearing materials are high porosity ratio and relatively large size of particles. A material, such as clay, may be highly porous and yet substantially impervious due to the minute size of its grains and resultant high surface fusion. The most favorable formations by far are sandstones, conglomerates and uncemented sands and gravels, although these are not always good water-carriers. Deposits of sand are often too fine-grained to be used as direct sources of supply, but may be valuable as slow feeders to some adjoining coarser medium. Limestones and dolomites are poor carriers except as they may carry water through fissures which are apt to be present. Hard rocks such as granites and gneisses are very dense but sometimes are fissured and decomposed near their surface and may there yield considerable water.

Classification of water-bearing formation

Water-bearing formations may be roughly divided into three classes, depending upon their extent and geologic origin.

1. Broad underlying formations of porous material, usually of considerable thickness and of fairly uniform character, constitute by far the most important class of water-bearing media. Outstanding examples are (a) the Tertiary deposit of sand and gravel underlying a large part of the western plains, (b) the sand and gravel

deposits of the so-called "Coastal Plain" which borders for a width of 100 to 200 miles the Atlantic and Gulf coasts from Long Island to Texas and extends up the Mississippi Valley to the Ohio River, (c) the sandstones in the eastern part of the Dakotas and parts of Nebraska and Kansas, and (d) the sandstones of southern Wisconsin, northern Illinois and eastern Iowa.

In such formations, relatively few scattered borings often yield reliable knowledge of the strata and numerous existing wells will usually be found from which valuable information may be obtained. Limestone strata may, as in Indiana and Kentucky, carry considerable water in fissures, but, as a class have the disadvantages of limited storage, hard waters and uncertain yield.

2. Deposits of porous material in old lake-beds and river-beds are the source of many of the shallower supplies. They are usually covered by other and less pervious strata and often alternate with non-pervious or less pervious layers. As a class they are much more limited in extent and capacity than the formations above-described. Examples of old lake deposits are numerous in the Western mountain region. Old river channels filled with porous debris may carry veritable underground streams and may in places underlie the modern streams. Pueblo, Colorado is supplied from such a gravel bed and many Western streams, where they emerge from the mountains, have created similar deposits.

3. Deposits of sand and gravel in the drift are numerous in the Northern states and are the source of many small supplies. They are likely to be irregular in composition and outline and very uncertain in extent. They occur in former stream-beds and also in thin irregular strata lying mostly in valleys and along moraines and usually are covered with more or less clay.

General features of ground water flow

The flow of water in underground strata is subject to many of the laws affecting surface and pipe-line flows-the hydraulic gradient must fall in the direction of flow and cannot be at any point lower than the surface of the body of water into which the flow discharges; the velocity of flow is a function of the steepness of this gradient and of the resistance to flow offered by the material in the stratum; for equal velocities the resistance is greater in small passages (or interstices) than in large ones.