numerous small rivulets. This system is now fed by a vast net work of underground tile which is continually supplying fresh, clear, cold water. The Skunk river with its branches, traverses the eastern part of the county. Lake Cairo, better known as "Mud Lake" is located near the centre of the county on the line between Hamilton and Lyon townships. This lake formerly covered about 1,200 acres and was a great rendezvous for wild game. In late years it has been drained, and, but for the still well defined banks, that border of the old bed, one would scarcely know that a lake had ever existed there. In the east part of the county, in Rose Grove township, was Iowa lake, almost as large as Mud lake. This too has been drained and converted into farm land. In the southern part of the county, in Ellsworth township, is "Wall Lake,' almost entirely surrounded by Morainic hills. This lake is still in existence. It is only about half the size of the other lakes. It is shallow and filled with rushes and other aquatic plants and probably at some time in the not very distant future, it too will be converted into farm land. Boone river has many natural advantages. Beside revealing along its banks much of geological interest, it for many years furnished power for a number of mills. This little river, silent and unpretentious in dry weather but stormy, turbulent and dangerous in flood times, has by reason of its economic value earned a place in history. In 1910, Mr. Geo. D. Dobson and T. L. Blank, acting under direction of the Iowa State Drainage Waterway and Conservation Commission, made a thorough examination and survey of the Boone river. Below is given a report of their findings made by Mr. L. V. Hites, secretary of the commission: THE BOONE RIVER-DESCRIPTION The Boone river rises in the northwestern part of Hancock county and flows in a southeasterly direction to the vicinity of Webster City in Hamilton county, where its general course changes to the south and southwest to its junction with the Des Moines river at a point about three miles from Stratford but in Webster county. The total length of the river is about 98 miles by river measurement, and 65 miles by air line. It has a drainage basin above Webster City, the area drained by the river being about 100 square miles, making a total of 920 square miles. The latter area was not considered in the calculations of stream flow used in this study. CHARACTER OF VALLEY The valley of the river throughout the territory covered by the surveys is comparatively narrow and deep, rarely exceeding one-half a mile in width, and often as narrow as 500 feet at a height of 80 or 90 feet above the river bed. The banks of the river are in general about 12 to 20 feet high, backed by a second bank 4 to 10 feet high and 10 to 200 feet back from the river. The slopes of the sides of the valley are comparatively steep, varying from vertical bluffs, where native rock outcrops, to slopes of about a 11⁄2 to I pitch which rise to a height of from 50 to 150 feet above the river bed. The bed of the stream and the nature of the soil through which it runs are variable. The lower five or six miles of the river valley, from the junction to the vicinity of Bell Mill, is characterized by a wide flood plain and the channel is tortuous and frequently interspersed with sand and gravel bars. The soil is a rich river silt. Near the Bell Mill bridge, the character of valley changes. Coal outcrops in the bluffs, and the river bed is a sort of black or blue clay. The surface of the native limestone is at this point about 10 feet below the bed of the river. From the Bell Mill bridge to the Tunnel Mill bridge, the river bed is clay or shale covered with sand, the depth of bed rock in this section varying from five to ten feet. Coal outcrops are frequent, and though the veins are quite thin, they contain exceedingly good coal. Sandstone and limestone outcrop about one-quarter of a mile above the old Tunnel Mill dam and form the bed of the river. These outcrops are characterized in a number of places by vertical bluffs in which 20 to 50 feet of lime and sandstone is exposed. No out-crops of native rock appear from Bone's Mill bridge to the Allbright bridge, but rock foundation is only a few feet below the bed of the river. There are low bluffs of native rock from a point a half mile below the Millard bridge to a short distance above the Chicago and North-Western Railroad bridge. From this point to the end of the survey no more outcrops appear and no probings were made for foundation on account of the large number of boulders in the soil. DISCHARGE The discharge of the Boone river at various seasons of the year is a factor very difficult to determine, and in fact, could not be accurately computed, without a series of gaugings and discharge measurements covering a number of years. However, during the month of August, 1910, the survey party took an accurate wier measurement of the discharge one-fourth of a mile below the Haskell bridge. This measurement shows a discharge of 12.6 second feet which, according to the testimony of people acquainted with the river and according to the most accurate data obtainable in regard to the run-off for the watershed of the river, is about one-third or one-half of the usual minimum discharge. Since this past season has been one in which all previous low water records have been broken, 20 second feet could be taken as the minimum discharge upon which to base power estimates. The maximum discharge of the river could only be obtained in a very rough way. High water cross sections were taken at several points in the river above the Millard bridge, and the slope of the river determined. With these factors, the maximum flow was estimated by means of Kutter's formula and was found to be about 7,000 second feet. This figure is for the year 1903, during which this section of the country experienced the heaviest rainfall in many years. FLOODS The floods of the Boone river are usually very sudden and of short duration. This is a favorable factor for the development of water-power since the quick passing of floods shortens the time of low head due to high water. FALL The total fall of the Boone river from the upper end of the Webster City reservoir, about eight miles above Webster City, to its junction with the Des Moines river, a point about twenty-eight miles below Webster City, is 133.5 feet, giving an average of 3.73 feet per mile. In some places however, the gradient is as much as eight feet per mile, while in other sections it reduces to less than three feet per mile. The maximum fall attained at certain points is found, where there is a succession of rapids as, for example, just below the Allbright bridge and about onehalf mile below the Millard bridge. The average fall of the river at various sections is shown by the following table: Before going into the calculations, as to the power to be developed and the location of power sites, it would be well to call attention to the results of the survey of the Webster City reservoir site. This investigation has shown that an earth dam 26 feet high to the flow-line and 1,200 feet long on top, could be built just above the Chicago and North Western railroad bridge, north of Webster City, which would impound about 8,500 acre feet of water. The reservoir would extend about seven miles up stream and would have a superficial area of 647.5 acres when full. The cost of such a reservoir, including the expenses incurred in building the dam, installing controlling devices, and buying lands necessary for the reservoir, would be approximately $35,000. The flow line of this reservoir was taken at the assumed elevation of 210. If the elevation of 197.5 be taken as the lowest elevation to which the water should be drawn, the reservoir would have an available capacity of 6,250 acre feet with a minimum head of 13.5 feet to be used in developing water power. The superficial area at the 197.5 foot contour is about 375 acres, and the length of the reservoir at this elevation is approximately four miles. From 70 to 90 horse power could be developed continuously at this dam. This power could be measurably increased by the use of a steam auxiliary to carry the plant through the dry season. If this reservoir were to be used for power only instead of being used to regulate the flow of the river, the horse power developed could be practically doubled. If the 6,250 acre feet of storage be applied toward increasing the dry season flow of the Boone river, it would amount to 35 second feet for 90 days on a 24 hour basis. Ninety days were assumed as the time through which the flow of the reservoir was to be distributed, since that number of days would easily cover the low water period. Adding this 35 second feet to the minimum flow of the river gives a total dry season flow of 55 second feet, which is safely the minimum flow that could be expected with the aid of this reservoir, since it would seldom be called upon to supply water to the river more than 75 days. POWER POSSIBILITIES-SIZE OF PLANTS A few statements in regard to the water-power plants in operation in this state at the present time will make clear the reasons for the conclusions drawn from these studies. There are 101 power-plants in operation in the state, of which 87 have reported to this commission. Of this number 60 develop 100 horse power or less, with an average head of 9.6 feet, and of these, 27 develop 50 horse power or less, under an average head of 9.5 feet. This average head would reduce to about eight feet if three plants which utilize the extraordinary heads of 20, 30 and 50 feet were left out of the calculations. We find also that the majority of the plants developing over 100 horse power are on rivers which have a minimum flow several times that of the Boone river. Hence, it seems reasonable to conclude, that in suggesting power projects for this river, plants of the above mentioned capacities would be the most practicable, and, in fact, the only kind feasible. BASIS OF ESTIMATE In the following considerations of power projects, no attention has been paid to the question of the use to which the power would be applied, but since there always has been a use for such power, it is safe to say that it would be saleable in some form or other. In the estimates which follow, all calculations of horse power are for a theoretical horse power, minus a 20 per cent loss, which would give approximately the power that could be delivered at the plant. On account of the large flood discharge of the river, most of the dams suggested would necessarily have long spillways, or be submerged dams. Concrete dams would be practicable in several places on account of the presence of materials for their construction. Timber dams would probably have to be used in several locations where the small amount of power available would not permit of such expenditure as a concrete dam would demand. BELL MILL SITE The lower five miles of the river present no very good locations for dams of any size worth mentioning, and the lack of good foundation makes dam construction unfavorable for this section. There is, however, a good dam-site about two miles above the old Bell Mill dam. A dam here, if made from ten to twelve feet |