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Sitka Sedge State Natural Area Hydrology Modeling

Oregon Parks and Recreation Department (OPRD) has contracted Pacific Groundwater Group (PGG) and ESA to perform a comprehensive hydrological analysis of potential interactions between tidal surface water inside the Beltz Dike and groundwater levels in the neighboring town of Tierra del Mar, Oregon.  This work will build on initial hydrological modeling, groundwater analysis, and data collection from previous years. Outcomes of detailed modeling and analysis will inform future decisions for habitat restoration on OPRD property, especially regarding potential effects on groundwater that might result from increased tidal exchange in the estuary.

PGG and ESA are currently reviewing available data and investigating potential modeling approaches and study design alternatives.  After this initial phase of review, the consultants will present findings to OPRD and a technical review panel in December 2017 or January 2018.  The presentation will allow OPRD and technical reviewers to refine the scope of the potential study and its methodology.  After this presentation, PGG/ESA will make final adjustments to the study design and will conduct geological probes, install groundwater monitoring wells, and begin development of a detailed existing-conditions conceptual model in winter of 2017/2018.  There will be two in-person stakeholder meetings to follow in 2018.  The first meeting will present results of existing conditions conceptual model development, present proposed methods for performing predictive groundwater modeling, and allow stakeholders to provide input and help guide methodology for further predictive modeling.  The first step in predictive modeling will be to find the thresholds of surface water inundation of the marsh at which groundwater effects would be expected in Tierra del Mar and to identify suitable parameters for estimation of sea level rise and climate change. The second meeting will present results of initial predictive modeling and thresholds for groundwater effects, and will focus on identification of potential further refinements and scenarios to be assessed by the predictive models.  PGG/ESA will then assess all of the identified scenarios and produce a final report detailing the predicted effects of each of the scenarios tested.

Sitka Sedge Hydrological Analysis Statement of Work (10/2017)

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