Water Resources Research Act Program

Details for Project ID 2005MT49B

Using paleoecology and paleoflood hydrology to assess the long-term ecological response of Montana's riparian and aquatic ecosystems to small natural and human dam features -- a pilot study

Institute: Montana
Year Established: 2005 Start Date: 2005-03-01 End Date: 2006-03-01
Total Federal Funds: $14,200 Total Non-Federal Funds: $28,400

Principal Investigators: Denine Schmitz, Duncan Patten

Project Summary: At the 2004 Dam Removal conference in Missoula which highlighted issues surrounding the removal of Montanas Milltown Dam, the nations leading dam removal scientists echoed a recurring and resounding theme; we need to increase our understanding of the long-term ecological effects of small dam removal on riverine ecosystems. We propose a pilot project to study the long-term ecological response of Montanas riparian and aquatic ecosystems to small natural and human dam failures and removals through paleoecologic and paleoflood hydrologic techniques. According to the National Inventory of Dams (NID), 76% of Montanas dams are over 40 years old. Thus, human dams in Montana are on the cusp of facing issues of economic and structural obsolescence, safety, and water quality. Dam removal is a new approach to restoring riparian and aquatic ecosystems impacted by obsolete and unsafe dams. Of the 467 dams removed as of 1999, less than 5% incorporated ecological studies (Hart et al. 2002). Consequently, we lack long-term knowledge of reach and watershed scale ecological responses to removal. The restorative potential of dam removal on ecosystem function depends on the ecological reversibility of the effects of the dam. The initial effect of dam removal is likely to increase longitudinal connectivity, induce channel incision upstream, and promote deposition down stream. Vegetation recruitment, species diversity, and successional processes within riparian areas will likely increase with time. Aquatic ecosystem attributes such as fish spawning habitat, macroinvertebrate habitat and water quality will also likely improve after the acute negative response to removal (weeks to months). However, until long-term data in response to dam removal is available, these predictions are nothing more than educated guesses. We will pilot the application of paleoecology and paleoflood hydrology methods to measuring long-term ecological response to dam failure and removal. Paleoflood hydrology is the use of flood stage indicators including sediment deposits, plant community composition, and community age structure, to reconstruct historic floods. We will use paleoecology and paleoflood hydrology coupled with field surveys of floodplain vegetation and geomorphology to assess the long-term ecological responses to natural and human dam failure and removal. Further, we will generate hypotheses to serve as the foundation for a multi-year, interdisciplinary project. The data generated from such a study will advance the knowledge of dam removal methods and their effects leading to healthier ecosystems and associated human communities.