1961. Snowfall, averaging 38 inches annually, is approximately 21 per cent of the total precipitation. The estimated gross evaporation in the Pembina Basin is 28.5 inches.

Runoff

The maximum stream flow of the year usually occurs in the latter part of March or in April, following the spring snow melt. Occasionally these high flows are increased and prolonged by accompanying rains. Following the spring runoff the flow rapidly decreases and usually remains low during the summer and fall months. Winter flows are very low or negligible.

During the period from 1921 to 1957 when hydrometric records were maintained, the average annual runoff of the Pembina River near Manitou was 73,000 acre feet. It has varied from approximately 1,000 to 245,000 acre feet. Similarly, during the period from 1921 to 1962 the average annual runoff at Walhalla was approximately 112,000 acre feet. Recorded extremes ranged from approximately 2,000 to 461,000 acre feet.

Economy

In considering the economic factors related to the development of the Pembina it is necessary to take into account not only the Basin itself but also the adjacent areas which might be affected. For this reason the area immedi

ately north of the Basin bounded by the escarpment, an east-west line through Morden, and the Red River is included in the economic appraisal.

The population of this total area is approximately 63,000 with 38,000 residing in Manitoba and 25,000 in North Dakota. Except for relatively high population densities in the urban communities, the population is less than 10 persons per square mile. The principal towns in North Dakota are Langdon, Walhalla, and Cavalier; and in Manitoba are Morden, Winkler, Altona, Killarney, and Boissevain.

The most important resource of the Basin is fertile soil. The area between the escarpment and the Red River is regarded as one of the best agricultural areas in either country. Climatic conditions and intensive use of land, particularly in the area south of Winkler, permit the growing of specialty crops. In addition to wheat, major crops include oats, barley, hay, flax, rye, sunflower seed, potatoes, sugar beets and vegetables. In recent years there has been a noticeable shift from cash grains to livestock.

The area is well supplied with rail transportation. A network of primary and secondary all-weather highways is adequate for commercial trucking in the area.

Industry is limited largely to food processing such as vegetable oil, vegetable canning, poultry eviscerating, food packaging, bakeries, potato chips and cat food. Employment throughout the region is principally in agriculture, related industries and service enterprises.

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Flood damage occurs on the broad flat plain east of the Pembina Escarpment. Flood flows from the Pembina River have escaped overland, some to the Tongue River Basin in the United States and some to the Plum River

10

Pembina, North Dakota during the spring flood of 1950

viigagogor Watershed in Canada. Although the Pembina floods do not usually coincide with flood peaks on the Red River, they do contribute to the magnitude and duration of major floods on the Red. It has been estimated that a flood equal to the magnitude of that of 1950 would, on the basis of 1963 prices, cause $2,730,000 damage along the Pembina River in the United States and $1,558,000 in the Gretna-Altona area in Canada; and when combined with the Red River flood peak of 1950 would cause $2,290,000 in the area near the mouth of the Pembina River and $11,278,000 between Emerson and Winnipeg.

Water Supply

Industries dependent on agricultural products have been reluctant to locate in the area because water supplies from the Pembina are not reliable. Ground water supplies are very limited and contain iron, sulphates and dissolved solids in quantities which exceed accepted drinking water standards. It has been estimated that the municipal and industrial water needs from the Pembina River in the year 2010 will be 0.6 million US gallons per day in the United States and 3.4 million US gallons per day in Canada. Supplies to meet these needs cannot be assured under existing conditions.