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largemouth bass migrated the most between the two ponds. Roundtail chub was the only native fish to move between the two ponds. 4. Within four months following draining, removal of nonnative fishes, and construction of a connection channel, nonnative fishes invaded and recolonized Gardner Pond. Within eight months, five species of nonnative fishes had successfully reproduced in Gardner Pond. Two conclusions were evident: a) Gardner Pond had again become a haven for nonnative fishes, and b) nonnative fishes are extremely resilient. Any ponds, whether in the 10-, 50-, or 100- year floodpl ain with bottoms irregularly shaped and contoured as depressions, provide perennial, off-channel habitats for nonnative fishes to grow and reproduce. Such ponds that are connected to the river allow sub-adult and adult nonnative fishes uninhibited access to the river and ~ other off - channel habi tats connected to the ri ver . Although such ponds are used by native fishes only during runoff, nonnative fishes appear to benefit more from such perennial, lentic habitats. In any event, ponds wi th depress ions provi de a constant supply source of nonnative fish that can potentially escape to the mainstem river. 5. Hotspot Pond did not drain following runoff in 1996. Therefore, an accurate assessment of whether nonnative fish populations could be reduced or eliminated was not possible. Usually, during low-water years, this pond is almost entirely dewatered by late-August or early- September leaving only a mud flat at the upper end. Irrigation waste water that flows through the pond to the river is the only source of water. The only habitat available for fish is near the connection channel near the river. However, during high-water years, such as 1996, thi s pond does not comp 1 ete 1 y drai n 1 eavi ng adequate water depths for fish to survive during the winter. In addition, groundwater levels during high-water years probably help retain pond water levels longer than during low-water years. If ponds are rec 1 aimed, steeper bottom slopes found in Hotspot Pond wi 11 be required for ponds to drain during high-flow years to reduce or eliminate perennial habitat for nonnative fishes. RECOMMENDATIONS Major recommendations (underscored print) are: 1. Avoid ConnectinQ Isolated Ponds to the River That are Deep Depressions. Floodplain habitat should not contain irregular-shaped, deep depression ponds. These type of habitats are perennial havens for nonnative fishes and provide potential sources for nonnative fishes to escape to the mainstem river. If deep depression habitats cannot be rehabi 1 i tated by recontouri ng and reshapi ng to provi de seasonal, ephemeral habitat, they should be sufficiently diked to prevent escapement of nonnative fi shes such as centrarchids and ictalurids. 11