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in an artificial side channel. This alternative is located opposite the diversion channel on the east bank of the river. The ladder is a series of rock drops and stilling pools and includes a gate for closure at the fish exit. No grating is proposed over the top of the ladder except at the fish entrance and exit. Thus the ladder is exposed to periodic flood inundation when flows in the Gunnison exceed 11,600 cfs. Consequently, some maintenance may be required after floods occur to remove debris accumulated in the ladder. The grating at the entrance and exit provides access to gates, which are proposed for controlling flows through the ladder and for isolating the ladder from the river. The rock drops serve as the baffle sections between each pool. A typical rock baffle includes several large boulders, approximately 4 feet in diameter to be placed in the center of the channel section with approximately 12 inch spacing in between. Smaller rocks are placed to the sides of the center boulders. Typical details are found in Appendix B. Upstream of each rock baffle is a pool that is 2 to 4 feet deep. The vertical drop between each pool is 0.25 feet. Maximum velocity is approximately 3 fps. Calculations indicate that this alternative lowers the water surface elevations at the Hartland headgate by less than 0.1 feet when the river flows are 350 cfs. For flows that equal or exceed 3,000 cfs, the change in water surface elevations at the headgate is negligible (0.03 feet or less). 6.2.1 Alignment The upstream end of the fish ladder is approximately 100 feet upstream of the dam and 60 feet from the attractive flow pipe intake. The fish entrance is located approximately 40 feet from the white water area at the toe of the dam. These distances are due primarily to the length required to grade this open channel fish ladder and are only several feet longer than Alternative I. 27 I I I I I I I I I I I I I I I I I I I