horsetooth reservoir is a man-made lake just west of fort collins, colorado, in southern larimer county made for recreation purposes, and is the main water supply for the poudre valley. the reservoir was a part of the colorado-big thompson project. this project was made to move water from the west slope to the east slope. the water is used for local farms, hydropower, and drinking water for northern colorado. the lake is 6.5 miles long and had 25 miles of shore line with 4 camping areas, 111 campsites total, and 4 boat-launch areas. the primary activities are fishing, power boating, water skiing, hiking, and camping.