Watershed & Stream Assessment, Monitoring and Restoration

To achieve long-term success on watershed and stream restoration projects demands a complete understanding of the physical and biological processes occurring within a channel. ENW’s Watershed and Stream Restoration Division evaluates the entire contributing watershed for each stream-restoration project. This investigation approach provides team members with extensive insight into a channel’s dynamics and allows us to examine the systemic processes within the channel's reach.

ENW staff have a wide range of stream and watershed assessment, monitoring and restoration experience, including:

·         Comprehensive watershed and stream assessments

·         Restoration of natural systems

·         Fluvial geomorphology and river classification

·         Erosion assessment, monitoring, and mitigation

·         Long-term environmental health monitoring and analysis

·         Wetland design and construction

·         Wetland delineation

·         Delineation of flood-prone areas and flood plains

·         Culvert/bridge sizing

·         Fish passage improvements

·         Steam channel monitoring

·         Instream habitat restoration

·         Riparian habitat restoration

·         Stream-bank bioengineered stabilization

·         Surface water – groundwater interaction and modeling

·         Sediment quality investigation

·         Stream water quality assessment

·         Bio-ecological benthos assessment

PROMINENT PROJECTS

National Study of Water Management During Drought US Corps of Engineers

Declining groundwater resources have troubled the Umatilla Basin for many years. As a contribution to the National Study of Water Management during Drought, Neil Woller was asked to formulate an index system of groundwater resources for use in conjunction with the existing surface water index in use in Oregon, so that regulators and planners could evaluate the availability of water for irrigation and assessment of hardship on groundwater users. The index was developed to be appropriate for the complex hydrogeologic character of the Umatilla Basin, but is applicable to any basin. The groundwater index system is pyramidal in character, describing changes in groundwater conditions on local, aquifer, and basin levels.  The index has analytical and predictive capabilities useful for regulatory and legislative purposes.

Chamokane Valley, Okanogan Highlands

Washington: Declining water resources were affecting a fish hatchery constructed by a large federal agency. Neil Woller was asked to evaluate conditions that might be impacting the hatchery’s water supply. Neil researched historical surface water discharge records, climatic records, crop and water usage changes within the valley, new wells in production, and surface and groundwater management by state and federal agencies for the entire basin.  The findings indicated that the region was in the seventh year of a significant drought, with very low snow packs on the surrounding highlands during winter. The drought resulted in declining water levels in the valley’s wells and decreasing spring flows. Neil explored options for developing additional water supply for the facility.  

Residence Skamania County, Washington

Lynn Green prepared a Water Mitigation Study designed to bring the subject property, located in a federally designated National Scenic Area, into compliance with county, state, and federal land-use regulations. The proposed work plan was designed to be protective of the environment during proposed site modifications and to provide ecological benefits to the surrounding areas.

Successful watershed and stream assessment and restoration is based on understanding the fluvial morphology, hydrologic setting, climatic factors, habitats, and ecosystem functions of a particular stream reach. The natural condition or potential of an impacted stream reach may be compared to a similar stream reach that has not been impaired (i.e., reference reach). ENW provides full-service stream restoration capabilities incorporating stream habitat assessments, Rosgen stream classifications, hydrologic/ hydraulic analyses, water quality assessments, and detailed stream restoration plans. 

Stream restoration can provide a low-cost solution to chronic erosion and sedimentation problems, resolve water quality issues, and/or to restore habitat. Whether the project is a master-planned residential community, commercial development, golf course, public land, or private residence, stream restoration may provide an opportunity to enhance the landscape and the environment by improving water quality for important beneficial uses such as irrigation, storm-water management, recreational use, habitat, or aesthetic quality. ENW also conducts these studies to establish baseline water-quality conditions and/or to develop long-term water-quality monitoring programs. 

By completing a detailed assessment, ENW can develop a restoration plan for the stream that is cost-effective, eliminating redundant efforts and simplifying post-restoration monitoring. ENW applies useful classification systems as part of the overall stream restoration process based on methods described by Dave Rosgen, the U.S. Forestry Service, and the Natural Resource Conservation Service’s (NRCS) Stream Visual Assessment Protocol. 

ENW’s team of professionals address all facets of the restoration design process so that local, state, and federal agency requirements are met. ENW conducts the necessary hydraulic/hydrologic modeling that incorporates bankfull width, depth, channel and bank slope, and flow velocity as well as dimensionless ratios of various stream geomorphological properties (based on the work of Dave Rosgen) to identify the most appropriate restoration technique. Restoration techniques include instream structures (i.e. cross vanes, weirs, and step-pool complexes) and bioengineering methods such as cut or fill, vegetated geogrids, live-staking and fascine bundles. ENW is experienced completing work throughout the Pacific Northwest region, which facilitates timely plan review and implementation. Our experience and dedication to detail allows for the most appropriate, cost-effective solution to be determined. ENW works closely with the selected contractor to ensure that the plans are implemented to specifications, and oversees the completion of the as-built structures.

Long-term monitoring of a restored stream provides data that determines the success of restoration. Monitoring may also be used to evaluate whether a stream has adjusted to land use changes in a watershed, which can affect water quantity and quality. ENW hydrologists and geologists conduct post-construction monitoring efforts, focusing on the restored stream morphology and channel system, survival of riparian plantings, and identification of water quality and habitat benefits derived from the project.  Monitoring efforts are developed in accordance with permit conditions and are summarized in an illustrated report documenting all findings and restoration activities.