Harnessing the Hydrologic Disturbance Regime: Sustaining Multiple Benefits in Large River Floodplains in the Pacific NorthwestEPA Grant Number: X3832205
Title: Harnessing the Hydrologic Disturbance Regime: Sustaining Multiple Benefits in Large River Floodplains in the Pacific Northwest
Investigators: Gregory, Stanley V. , Hulse, David , Haggerty, Roy
Institution: Oregon State University , University of Oregon
EPA Project Officer: Packard, Benjamin H
Project Period: May 1, 2005 through April 30, 2008
Project Amount: $287,999
RFA: Collaborative Science & Technology Network for Sustainability (2004) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , Sustainability
Large river floodplains in the Pacific Northwest are the most ecologically and economically productive lands in the region. Intensive human settlement and use of these lands compels efforts to seek multiple benefits as urban areas continue to grow. Recent riparian research reveals an opportunity to simultaneously derive water temperature reductions, terrestrial and aquatic habitat enhancements, increased recreation and improved non-structural flood storage in large river floodplains. Potential to reduce water temperature is especially compelling due to the convergent mandates of the federal Clean Water Act Total Maximum Daily Load (TMDL) for elevated temperature as a water quality limiting factor and federal Endangered Species Ace concerns for elevated stream temperature effects on listed salmonids and other native riverine species.
A mechanism could be created by which entities that discharge heated effluent into the river from point sources would fund the removal of river revetments and levees, as well as the retirement of lands in the floodplain, to allow the river to spread onto those lands and access additional hyporheic gravels. Revegetation of riparian areas or newly created island could also be undertaken to provide greater shade and an additional cooling effect. In exchange for arranging and paying for these non-point sources of temperature "over control", the point-sources entities could receive credits in a trading scheme that could be used to offset their thermal discharges and allow them to comply with temperature wasteload allocations imposed through the TMDL process and incorporated into National Pollution Discharge Elimination System (NPDES) permit conditions. Cost to these entities to pay for removal of river blockages, retirement of lands adjacent to the river (through fee titles acquisition, conservation easements, or other means), and revegetation activities, could be considerably less than the cost to construct and operate engineered on-site temperature control would have the ancillary benefits of restoring off-channel habitats and creating other conditions favorable to riparian-dependent wildlife while potentially increasing non-structural storage and slowed release of floodwaters, thus reducing downstream risk to flooding.
This research is an attempt to identify innovative and cost-effective ways to comply with regulations for managing fresh and treated wastewater while maximizing and sustaining the benefits to affected communities. A meeting was organized by the Willamette Restoration Initiative in Salem, Oregon in November 2003 convening approximately fifty of the relevant stakeholder to discuss the possibility of achieving and sustaining multiple riverine benefits with the express aim of thermal modification through increased hyporheic connectivity. The over-arching conclusion of the meeting is that the answers to three questions are required to proceed:
- what scientific evidence is necessary to understand the mechanisms by which the water temperature reductions observed to date occur?
- where are the riverine features that hold the most promise for such temperature reduction effects?
- and what types of regulator and local citizen acceptance are necessary to bring about such change?
The proposed work will build on prior research to bring better empirical data, improved models of hyporheic exchange and tolls for geographic prioritization to an iterative, interactive citizen process of identifying where thermal modification and related benefits could occur given socially plausible measures.
Outcomes will be presented at project-convened regional conferences, national venues, and published on websites and in peer-reviewed journals. Beneficiaries will include key state, regional and national constituency groups concerned with water temperature, riparian habitat and flood damage reduction.