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Show BOIS DE SIOUX RIVER LITIGATION 525 pert, says that when the lake is at a mesne height of 974, the Minnesota ditches are responsible for a permanent increase in the level of from three to six inches, say four inches, and that in time of flood when the lake rises to 977, the ditches account for ten inches. The varying esti- mates of these two principal witnesses for North Dakota do not seem to rest on definitely ascertained data. We have no government or other gaugings of the flow from the Mustinka into the lake before the cut-off was completed in 1915. The first of such gaugings was taken near Wheaton in March, 1916. The cubic feet of flow into the Lake from the Mustinka before the cut-off ditch was constructed, is therefore a matter of judgment rather than calculation, dependent on the prob- able run-off during the period of floods from the watershed, the extent of detaining basins that then existed, the possible evaporation under then conditions, the cross sections of the present ditches compared with probable cross sections of the channel of the old river as it was before the ditches and the straightening of the river, and the extent to which it then overflowed its banks in time of flood. Most of these factors and their effect were a matter of unsatisfactory estimate in the absence of actual gaugings and measurements of the flow into the Lake from the old Mustinka in a state of nature. The situation was indeed complex, as Dean Shenehon expressed it. He said he could not say definitely how large a detaining basin was destroyed by the new work. He left the subject with this general statement : "I looked over that country and in my judgment all that complex of cut-off canals and state ditches and improved Mustinka Eiver from the outlet of the cut-off to Lake Traverse and the laterals or ditches entering it in my judgment increased the run-off of water in flood con- ditions substantially fifty per cent. ... I have viewed the conditions, and in my judgment as an engineer, which is the best judgment I can give you, the run-off is fifty per cent, greater than in a state of nature." Having thus reached the proportion of increase, the witness's esti- mate was that the flow into the lake from the Mustinka in a state of nature was 1,600 cubic second feet and that the ditching by the State added 800 cubic feet and that increase accounted for maintenance of the high lake level and the continuous flood complained of. This conclusion was largely dependent on the assumption that there was what Ralph called the Delta Zone covering from seventy to one hundred square miles lying immediately east of Twelve Mile Creek and extending east toward the Upper Mustinka and north beyond the line of the cut-off and old ditch. Both Ralph and Shenehon main- tained that this was a low, moist, marshy region, with a rim which acted as a retaining basin for the overflowed waters of the confluence of the three Mustinka constituent streams, and that the cut-off, by draining this, prevented the former heavy loss by evaporation, acceler- ated the flow and increased the volume of the water carried down to the lake by one-half, would give every recurring flood the same effect. Ralph also insisted that in the state of nature before the ditching, whenever there was high water in the Mustinka, the water flowed north over a ridge or low height of land into the sources of the Rabbit River in Tintah Slough, that thus a very considerable amount was carried directly to the Bois de Sioux basin, some fifteen miles north of the Lake, and that by this diversion, the level of the Lake was |
