Meacham Creek - Bonifer Reach Floodplain Connectivity III

This is year 3 of the Meacham Creek - Bonifer Reach Floodplain Connectivity project.



The overall goal of the project continues to be to restore, enhance and protect floodplain habitat and restore stream morphology while enhancing habitat for fish along Meacham Creek. Project objectives include:



•Restore floodplain connectivity through removal or modification of levees/spur dikes.

•Increase hydraulic connectivity including hyporheic and surface water exchange and improve the four-dimensional hydrologic mosaic.

•Enhance and increase instream habitat quality and diversity for key aquatic species while restoring channel morphology and instream processes by incorporating habitat features into the channel and throughout the floodplain.

•Enhance growing conditions and improve riparian plant density, diversity, and vigor by using native vegetation species in the floodplain.



Ultimately these objectives are expected to reduce summer stream temperatures, improve overall channel stability and floodplain connectivity, water quality, and improve aquatic habitat conditions. Proposed actions are expected to specifically increase channel connection to the floodplain, allowing for the evolution of a more stable geomorphic streambed structure. Cooler in-stream water will result from increased riparian shading in the improved riparian habitat zones that evolve from the stable channel.



For FY 2017, the PCSRF funds were used specifically for activities along 3.8 miles of stream (Meacham Creek RM 1.9-5.7) including levee removal, new channel excavation, and reconnection to the floodplain. This work continued into year 4 (PCSRF project 18-Umat-02) so metrics are split acccoridingly between these two projects. BPA funds were used for stream dewatering purposes. The OregonWatershed Enhancement Board (OWEB) project #217-6049-14269 is also connected to this project but the metrics associated with that funding source will be recorded by them.

Over the last 150 years, much of the Meacham Creek watershed has been negatively impacted by road construction, agriculture and livestock grazing, the Union Pacific Railroad and other human activities. Direct channelization and the construction of levees and spur dikes also occurred in Meacham Creek following the 1964 flood (Andrus and Middel 2003), which have altered natural hydrologic and geomorphic processes that shape the form and function of Meacham Creek. Channel sinuosity has greatly decreased from historic conditions from 1916 to present (Andrus and Middel 2003, Tetra Tech 2010a). The decrease in sinuosity corresponds with the construction of levees and spurs dikes and a loss of valley floor width from the railroad encroachment (Andrus and Middel 2003, Tetra Tech 2010b). As a result of extensive levees, spur dikes, cattle grazing, and other impacts, Meacham Creek is subject to problems associated with decreased floodplain connectivity, degraded channel structure, limited large wood and sources, altered hydrology and sediment transport, poor riparian cover and conditions, and elevated water temperatures and rate of heating (Tetra Tech 2010c, CTUIR 2014). Key in limiting salmonid fish production, these watershed impacts led to high stream temperatures, lack of summer flow, limited floodplain connectivity, lack of overall habitat complexity and side-channel habitat, and limited in-stream shade and cover. Specifically identified primary limiting factors for the Meacham Creek watershed include in-channel characteristics, floodplain/riparian, sediment, and water quality – temperature (CTUIR 2015). Each of these factors limiting fish production has contributed toward Middle Columbia River steelhead and Columbia River Basin bull trout that are present in the Meacham Creek watershed being federally listed as threatened under the ESA of 1973, as modified (Tetra Tech 2010c, 2013a).





Habitat enhancement in the upper Umatilla focus area, and specifically in Meacham Creek (refer to Focus Area in the map below), is expected to reduce summer stream temperatures, improve overall channel and floodplain stability, and ultimately improve aquatic habitat conditions. The CTUIR natural resource staff expects measurable response in key characteristics of hydrology, geomorphology, and connectivity resulting in improved riparian vegetation conditions and improved conditions for important aquatic species. Specifically, proposed actions are expected to improve connectivity between surface flow and shallow groundwater in the channel and floodplain, and the riparian forest. This will result in cooler in-stream water due to the influence of increased hyporheic interaction (e.g. buffering and lagging Arrigoni et al, 2008). We expect to observe increases in the incidence of cold water refuge areas for salmonids (e.g. pools and reaches downstream of meander bends or islands). Adverse impacts associated with the implementation actions are expected to be temporary and insignificant when compared to the expected long-term benefits to the upper Umatilla focus area ecosystem.



The future management of these project areas will remain the same as they are currently. The CTUIR owns most of the project areas with some individual allotments interspersed. Since the purchase of the property, the only livestock grazing that has been permitted is the use of goats to control invasive plant species. Furthermore, there is a fence running the full length of the railroad right-of-way to prevent trespass cattle grazing.