Evaluation of wetland creation and waterfowl use in conjunction with Abandoned Mine Lands in northeast Wyoming

Abstract

During 1991 and 1992, we studied 92 wetlands, including open water (ponds) and emergent communities, created as a result of Wyoming Abandoned Mine Lands’ (AML) reclamation efforts in northeast Wyoming. Through these activities, over 300 wetlands were filled, reclaimed, created, or otherwise modified. For mitigation purposes, wetlands to be filled or modified were first evaluated using a Wetland Habitat Value (WHV) Model. Using the model, wetland losses were mitigated by increasing the WHV of some wetlands or by creating new wetlands elsewhere. We evaluated model performance in offsetting wetland loss and how well the model predicted waterfowl use. We also compared post-reclamation wetland sizes to those predicted by engineering plans and submitted for Section 404 permit approval. In our study, predicted WHVs were overestimated at 100% of the wetlands for which pre-reclamation WHVs were available (n=8). The most commonly overestimated variables were size, fraction of emergent cover, adjacent upland cover, and the number of bays and peninsulas. We obtained pre-construction size estimates for 64 of the original 80 wetlands. Fifty-five of 64 wetlands were smaller than pre-reclamation engineering goals. The WHV Model accurately predicted use of wetlands by migrating and breeding Canada geese (Branta canadensis), migrating dabbling ducks, and migrating diving ducks. Future users of the model must be careful not to overestimate results of planned mitigation efforts. Predicted size of constructed wetlands may be commonly overestimated; this possibility should be considered in mitigation plans, especially those involving wetland destruction.