CONSERVATION OF THE WILD LIFE OF THE SANDHILL LAKES
By G. E. Condra, Dean and Director, Conservation and Survey Division, The University of Nebraska

     The Conservation and Survey Division of the University has mapped more than 1,000 of Nebraska's sandhill lakes, The Division has studied the chemical composition of the water, also the plant and animal life of the lakes, and secured some data regarding the origin and features of these lakes. The following statement is based on these investigations.
     Origin of Lake.. There are a number of erroneous assumptions regarding the origin of these lakes. Some hold that their water comes from deep-seated sources or from underfiow originating in the mountains. The fact is, that most of the lakes originate from ground water replenished from rainfall which is absorbed at once by the sandy soil and loose bed rock, under which are thick, impervious layers which prevent the loss of water to deep-seated sources. Much of the rainfall Is stored in the porous ground and not on the surface of the land. The round is filled with water to above some of the valley floors, i. e., to the level of the drainageways of the valley floors. The exposed ground water is the lakes. The height of the water table is ever changing, likewise the depths and areas of the lakes. Although some of the lakes are but temporary ponds above the water table proper, the surface of most of them is the general water table of the region, the fluctuating position of which is determined by rainfall, evaporation and drainage. There is a very slow underfiow of the round water towards the lower lands and the comparatively few surface drainage ways. Rainfall and the adjusting water table lift the ground water to the height of the surface drainage. Evaporation and drainage lower it and the lakes. As the water table rises, the lakes deepen and enlarge. As it lowers, they contract to dry beds. The lakes do not all rise or fall at the same time throughout the region because of the variation in rainfalls, differences in topography and the position of the drainage ways.
     As a general rule, the lakes enlarge during spring and early summer, when there is most rainfall; fall during late summer, with the heavy evaporation; and rise again in the fall time, when there is less evaporation. The adjustment of the ground water from the hills or higher land to the valleys where there is surface drainage to the rivers heading in the region is a continuous, slow process, hence the run-off to the river is quite uniform. Although most rainfalls have little immediate effect upon many of the larger lakes, there are places in some of the valleys, having heavier soils, in which the water accu-

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mulates quite rapidly in the lakes as it does in the hard land regions. Elsewhere in the sandhill country, practicaly (sic) all of the rainfall, except that falling on the lakes, is absorbed into the soil, percolates to the ground water zone and begins its slow movement to the lower lands as underflow, whereby the gradient of the water table is flattened from the hills towards valleys. This movement or adjustment in most of the region is eastward or southeastward. There is, therefore, a quick storage of water supplied from the rainfalls and a markedly slow movement to the lakes and surface drainage, depending upon the distance and topography, both of which affect the gradient and the length of time the water of a rainfall may remain in the ground. Because of these conditions, only the seasonal distribution and the periodic fluctuations in rainfall affect the high and low stages of most of the lakes. Also, the water table and the lakes are lowered by opening the drainage ways from the lakes. It is raised and the lakes are held to their largest size and greatest depth by obstructing the surface drainage.
     The sandhill lakes are comparatively shallow. They vary much in size and form. Many of them have a seepage border, usually on the west or northwest, and are bordered in whole or in part by marsh that merges into meadow or hay flat land lying next to the hills. When expanding, the lakes encroach upon the hay flats. This is received with disfavor by the ranchmen.
     Cycles of Development. The lakes pass through stages of development. Some are young or new; others are mature, and some are decadent, i. e., lowering to a dry bed; These lake stages effect corresponding stages in the wild life development. The plant life of the lakes occurs more or less in belts or zones represented by prairie grasses, sedges, marsh plants, and open water vegetation. These belts invade one another as the lakes enlarge or contract. It is the story of invasion and of change from hay flat vegetation to that of the more or less permanent lake and back again through the cycle, which, if not controlled by man, recurs again and again. The plant distribution, serving as habitat and as food, determines in large measure the zonal distribution of the animals, such as the microscopic water forms, snails, leeches, frogs, fish, shorebirds, muskrats, etc. New lakes support little life; mature ones teem with living things of many kinds, each related to the others. Decadent lakes support little life.
     Most of the lakes are of the right chemical composition to support the lowest forms of plants which become food for microscopic animals. The plants of different kinds and the lowest forms of animals are fed upon by such animals as snails and leeches. These and other forms become the feed of fish, birds and mammals which in turn become food for man. It is a struggle in the natural scheme of existence. Here are physical and biological conditions which should be more generally understood and recognized in the management of the lakes and their wild life.

     Control of Lakes. The problem is to maintain the lakes and their border areas at stages that best support the production of hay, fish, muskrats and other animals. It is a matter of economic lake farming.
The state has taken steps to assist in the control and development of these lakes, first, by determining whether or not they should be drained for agricultural purposes, or retained to support wild life; and second, by using artesian wells to maintain the necessary depth and open surface for fish life especially. Also, investigations have been made of the relation of hay production to the depth of the water table in the sandhill valleys and lake borders. These show that a shallow water table produces most grass and hay and that drainage is detrimental at most places. The State Game, Forestation and Parks Commission is developing several of the sandhill lakes for public recreation, fishing and hunting.
     Many of the sandhill lakes are off-again, on-again in their support of plant and animal life. In their decadent stages there is death of everything that cannot migrate. In their mature stages, they afford habitats favorable for fish, birds and mammals. The dry lake beds are of little agricultural value.
     To show the nature and possibilities of the sandhill lakes, to decide which should or should not be drained for agricultural purposes, and to work out a comprehensive policy for their wild life conservation and management is a problem for further investigation and the intelligent consideration of all concerned.

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CLIMATE OF NEBRASKA
By Thomas A. Blair, U. S. Weather Bureau, Lincoln

     The salient features of the climate of Nebraska are briefly presented in the accompanying charts and tables. A long series of daily observations of weather conditions is necessary to ascertain the climate of a place. Weather observations were begun at Fort Kearney in 1849, and since then have been continuous at one or more stations in Nebraska. The number of stations slowly increased to twelve by 1875. In 1878 the Nebraska Weather and Crop Service was organized, and the collection and publication of weather data were placed upon a systematic and permanent basis, with regular reports from numerous volunteer cooperative observers in all parts of the state. Since 1897 this work has been under the direction of the Weather Bureau of the United States Department of Agriculture.
     Daily weather records are now made at about 140 stations in Nebraska, all but a few of them by unpaid cooperative observers, who are thus performing a valuable, even indispensable, public service. It is only by tabulating and summarizing these records that we come to a knowledge of the climate of the state, and it is thus that the following, data are obtained.
Table 1 gives the average temperature by months for the various sections and for the state as a whole. There is evident a gradual and fairly uniform decrease in temperature from the southeast to the northwest, showing the combined influence of differences in latitude. and in elevation.
     Closely connected with the temperature, and itself a climatic element of great importance, is the length of the growing season. This is usually taken as the period between the last killing frost of spring and the first of autumn. The average dates of these events in the different portions of Nebraska are shown in Maps 2 and 3. The average length of the growing season as indicated by these maps increases from 122 days in the northwest to 164 in the southeast. In individual years there is often a wide variation from these averages.
     The climatic factor of most general interest because of its direct influence on crop yields is the precipitation. The average annual precipitation in inches of water, as determined from all available records, is shown in Map 1. It ranges from over 82 inches in the southeast to less than 16 inches in a small area in the west.
     The precipitation by years and crop seasons for the years, 1850 to 1875, inclusive, is given in Table 2. These values are the best available estimates for this early period, but are not of equal accuracy with the later averages. Since 1876 the stations have been sufficiently numerous and sufficiently well distributed to give reliable averages for the six sections, and the combined section averages give reliable state

averages. These are set out by years and crop seasons in Table 3. The expression, crop season," as used in these tables, means the six months, April to September, inclusive.
The average snowfall in the state by seasons is given in inches in Table 4. Ten inches of snow will yield on the average about one inch of water. About 12 per cent of the total annual precipitation is in the form of snow.
In Table 5 are summarized for the four first order Weather Bureau stations in Nebraska, the average relative humidity, the average wind velocity and prevailing direction, the amount of sunshine expressed as a percentage of the possible amount, the average cloudiness, and the average number of days on which a measurable amount of precipitation falls. All these are important elements of climate.

TABLE 1.-- MEAN TEMPERATURE

Months	State	N. E. Section	S. E. Section	Central Section	S. W. Section	W. Section	N. W. Section
January	21.9	19.8	23.4	22.1	24.8	24.2	21.2
February	25.1	22.6	26.3	24.6	27.7	26.4	23.0
March	35.6	34.9	38.2	35.8	87.9	85.4	33.2
April	49.0	49.7	52.0	49.5	50.6	47.0	46.1
May	59.0	59.8	61-5	59.4	60.5	56.7	55.7
June	69.3	69.8	71.6	69.8	71.1	67.0	66.3
July	74.6	74.8	76.7	74.9	76.4	72.7	72.2
August	72.8	72.7	74.8	73.1	74.6	71.2	70.4
September	63.9	64.5	66.8	64.5	63.5	62.2	61.4
October	S0.9	51.7	53.8	51.4	52.5	49.2	48.2
November	36.7	36.8	39.6.	37.2	38.7	86.6	84.9
December	25.8	24.8	28.0	26.1	27.9	27.0	25.1
Year	48.7	48.6	51.1	49.0	50.7	48.0	46.6