Cottonwoods in this area that get that large usually have heart rot and can be dangerous. If most of the limbs and branches are falling on your side, the prevailing wind must be blowing them that way. The owner of a "danger tree" can be held liable for any damage if he is informed in advance. It may be time to cut and replant. Those types of trees often grow so fast that there might be only a couple years benefits lost before the new trees perform the same service. At least around here, the only things cottonwoods are good for is pulp for paper production (don't burn worth a darn as firewood) and it takes dozens of big ones to be worthwhile.