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backwaters and embayments are used by adult Colorado squaw- fish and razorback sucker as refuges and staging areas during runoff and as foraging areas during low flow. The require- ments of these target species cannot be universally satisfied with construction of a single type of feature. Enhancement of high-water and low-water habitats is needed. Interesting comparisons can be made between natural and manmade backwaters and embayments in the Yampa and Upper Colorado Rivers that reveal some of the more desirable aspects of these habitats. Diked side channels, built for erosion control, appear to offer valuable fish habitat during high flows, when the fish tend to leave the main channel and seek refuge in quiet areas. Adult Colorado squawfish use artificial backwaters as they use naturally-occurring ones. Diking side channels in areas inhabited by adult squawfish and razorback sucker warrants consideration for recreating backwaters lost to reduce flows and channeliza- tion. Earthen dikes placed at upstream ends of side channels to prevent the river from flowing through allow flooding from the lower end and are a desirable manmade structure. Dikes should not be allowed to breach, and side channels should have gentle gradients that allow backwaters to drain with descending flows and prevent the establishment of potentially competitive non-native fish populations. Habitat for juvenile and yoy squawfish and razorback sucker can be created from partially-breached dikes at heads of side channels. This allows the channels to flush silts and particulates during runoff, but to become slow-flowing backwaters during low flow that support high levels of macrophytes and insects for young fishes. Care .should be taken before creating these low-water habitats for native species since the presence of high densities of non-native species may pose serious competition/predation problems. Embayments can also be created to provide low-flow nur- series for young native fishes by diverting the river energy into an eddy effect. Wing dams and reinforced banks can cre- ate this digging action, but more study is needed to under- stand what substrates respond best to various strucCures. Abandoned gravel pits constitute unnatural riverine features that allow competitive and predaceous non-native fishes to flourish because they remain sheltered from- the river year around. These large, unnatural features should be permanently sealed from tfie river and managed as warm-water sport fisheries. Subterranean flow into these pits is sufficient to maintain good water levels and quality. Gently-graded gravel pits that flood during runoff but drain 534 with descending flow may benefit native fishes by providing r staging or resting areas during runoff while precluding - permanent populations of non-native fishes. Habitat enhancement to recover native fishes should utilize natural riverine features, where possible. Existing side channels, tributaries, old river channels and oxbows should be utilized for backwaters to insure a stable, long- lasting feature. The feasibility and expense of diking these channels will depend largely on access and side effects of the procedure. Excavating new channels or backwaters is not advised because the shifting na-Cure of the river is likely to fill these with sand and silt and render the operation a wasted expense. SUMMARY 1. Backwaters created by diked side channels resemble in appearance and function natural habitats. These benefit protected native fishes by providing resting, staging and feeding areas during high flow, and drain at low flow to prevent establishment of permanent populations of competitive non-native fishes. 2. Backwaters that persist at low flow are used by native fishes for foraging and resting. These are generally inundated and flushed of non-native fishes at high flows. 3. Side channels with breached dikes can provide low- velocity nursery habitats that flush of silts at high flow. These features resemble naturally-occurring habitats that can harbor large numbers of non-natives; so, community structure must be well known before constructing breach able dikes on side channels. 4. Embayments are important low-water nurseries and habi- tats for young fishes. These can be created with wing dams and reinforced river banks to direct river energy into an eddy effect that digs the embayment and builds protective sand bars. Embayments are flushed of silt by annual runoff and their short-term nature lessens potentially competitive effects of non-native species. 5. Large, deep, open-water gravel pits that are refuges for non-native fishes but attract native fishes during runoff should be sealed from the river and managed as warm-water fisheries and wildlife sanctuaries. This may reduce problems for native fishes associated with competition, predation and pathogens, and reduce the influx of non-native fishes into the river system. SAS