DAM. A construction of wood, stone, or other materials, made across a stream of water for the purpose of confining it; a mole.
2. The owner of a stream not navigable may erect a dam across it, provided he do not thereby materially impair the rights of the proprietors above or below to the use of the water in its accustomed flow. 4 Mas. C. C. 401; 13 Johns. N. Y. 212; 17 id. 306; 20 id. 90; 3 Caiues, N. Y. 307 ; 9 Pick. Mass. 528; 13 Conn. 309; 15 id. 366; 4 Dail. Penn. 211; 6 Penn. St. 32; 2 Binn. Penn. 475 ; 14 Serg. & R. Penn. 71; 3 N. H. 321; 3 Kent, Comm. 354. He may even detain the water for the purposes of a mill, for a reasonable time, to the injury of an older mill,—the rea sonableness of the detention in each particular case being a question for the jury. 12 Penn. St. 248; 17 Barb. N. Y. 654; 28 Vt. 459; 25 Conn. 321; 2 Gray, Mass. 394; 38 Me. 243. But he must not unreasonably detain the water, 6 Ind. 324; and the jury may find the constant use of the water by night and a de tention of it by day to be an unreasonable use, though there be no design to injure others. 10 Cush. Mass. 367. Nor has such owner the. right to raise his dam so high as to cause the stream to flow back upon the land of supra-riparian proprietors. 1 Barnew. & Ald. 238; 6 East, 208 ; 1 Sim. & S. Ch. 203; 12 Ill. 281; 24 N. H. 364 ; 8 Cush. Mass. 595 ; 19 Penn. St. 134; 20 id. 85 ; 25 id. 519; 33 Me. 237. And see BACK-WATER.
These rights may, of course, be modified by contract or prescription. See WATERCOURSE.
3. When one side of the owned by one person and the other by another, neither, without the consent of the other, can build a dam which extends beyond the jilum aquce, thread of the river, without comm,ttinfr a trespass. Croke Buis. 269; Holt, 40;
Mass. 2115 4 Mas. C. C. 397 ; Angell, Waterc. 14, 104, 141. See Lois des Bat. p. 1, e. 3, s. 1, a. 3; Pothier, Trait4 du Contra de So eidie, second app. 236; Hillier, Abr. Index ; 7 Cow. N. Y. 266; 2 Watts, Penn. 3'27 ; 3 Rawle, Penn. 90; 5 Pick. Mass. 175; 4 Mass. 401 ; 17 id. 289.
4. The degree of care which a party who constructs a dam across a stream of water is bound to use is in proportion to the extent of injury which will be likely to result to third persons, provided it should prove insufficient. It is not enough that the dam is sufficient to resist ordinary floods; for if the stream is occasionally subject to great freshets these must likewise be guarded against; and the measure of care required in such cases is that which a discreet person would use if the whole risk were his own. 5 Vt. 371; 3 Hill, N. Y. 531 ; 3 Den. N. Y. 433; Angell, Waterc. 336.
5. If a mill-dam be so built that it causes a watercourse to overflow the surrounding country, where it becomes stagnant and un wholesome, so that the health of the neigh borhood is sensibly impaired, such dam is a public nuisance, for which its author is liable to indictment. .4 Wise. 387. So it is an dictable nuisance to erect a dam so as to overflow a highway, 4 Ind. 515 ; 6 Mete. Mass. 433; or so as to obstruct the naviga tion of a public river. 1 Stockt. N. J. 754; 3 Blackf. Ind. 136; 2 Ind. 591; 5 id. 433; 6 id. 165 ; 18 Barb. N. Y. 277 ; 4 Watts, Penn. 437; 3 Hill, N. Y. 621; 9 Watts, Penn. 119.