The Colonial period, which lasted from perhaps 600 to about 900 A. D., is better known than the Pioneer, for it is represented at two other excavated sites in addition to Snaketown. These are Roosevelt 9:6, at Roosevelt Lake, Arizona,[48] and the Grewe Site which lies just east of Casa Grande National Monument.[120] By the end of Colonial times all of the distinctive traits which characterize the Hohokam were fully developed, and some had even begun to decline. The most spectacular accomplishment of this period, and for that matter of the whole culture, was the construction of a great system of irrigation channels which diverted water to the fields from the rivers.[57] At their first appearance, the canals were so well developed that it seems impossible that this marks the first attempt at such a project. Possibly the system had been developed in Pioneer times, or, perhaps, it had been perfected elsewhere first, but evidence to bolster either theory is still lacking. By 700 A. D., the canal system was well established and became increasingly bigger and more complex until the peak was reached between 1200 and 1400 A. D. The whole project is really amazing when one considers the tremendous amount of work which went into the construction and maintenance of the canals. The latter must have required almost as much effort as the original excavating, for silt was constantly being deposited. Canals were up to thirty feet wide and ten feet deep, and in the Salt River Valley they have been found to have an aggregate length of 150 miles. It staggers the imagination when one stops to think that this tremendous engineering feat was carried out with only the crudest of stone and wooden tools. The scope of such a project and the end toward which so much effort was directed tell us a great deal about the people who planned it. Undoubtedly such an undertaking indicates strong leadership and careful organization. Great numbers of people must have participated, and it undoubtedly took much careful planning to direct their labors. There must also have been some centralization of authority, since the canals served various settlements and these groups must have had some organization to direct their efforts toward the common good.