Public Hearing Draft (clean) - City of Bainbridge Island

2.0 Shoreline Inventory and Characterization
2.1 Summary
To characterize the Island’s 53 miles of shoreline, the City initiated a series of studies to update
the Shoreline Master Program with the most current science. A shoreline structure inventory
and two shoreline characterization reports were completed. The primary inventory and
characterization data is found in the Nearshore Habitat Characterization and Assessment,
Management Strategy Prioritization, and Monitoring Recommendations produced by Battelle
Laboratories for the City of Bainbridge Island in 2004 (Battelle 2004). The assessment uses a
conceptual mode to determine potential level of impact from alterations to the nearshore
environment. The conceptual model identifies nine controlling factors which represent
physical, biological, and chemical attributes of the nearshore marine habitats. The integrated
spread-sheet model and geographical information system developed by Battelle, quantifies
existing anthropogenic impacts by converting qualitative factor values to standardized scores.
The model’s scoring approach uses a 5-point scale to assign to qualitative categories to
potential impacts for the nine controlling factors identified in the nearshore conceptual model.
The model divides the shoreline into 201 reaches, which are then grouped into nine (9)
management units. The controlling factor score for each reach represents the predicted impacts
affecting nearshore processes. To allow Island-wide comparison across different types of
shorelines, a normalized index was calculated called the cumulative reach index. Controlling
factor scores are best used to prioritize conservation and restoration efforts in the nearshore as
indicators for identifying the probability for successful conservation and restoration strategies
(Battelle 2004).
The model uses ecological information collected by Washington Department of Natural
Resources (WDNR) for a regional shoreline inventory. The data is available through the
Department of Ecology, Coastal Atlas. Additional datasets from the City’s shoreline structural
inventory and other sources are listed in Table 3 in the Battelle document.
An Island-wide inventory of current geomorphic features and an accompanying analysis of
historic conditions was produced for the City in 2010 by Coastal Geological Services. This
study maps coastal geomorphic shoretypes (such as “feeder bluffs”) and prioritizes restoration
and conservation sites. The study includes current and historic mapping of coastal processes
and process-impaired areas. Report conclusions integrate a qualitative, coastal processes-based
prioritization with an objective of restoring and preserving coastal processes that sustain and
maintain critical habitats.
These documents can be accessed from the City’s website (www.bainbridgewa.gov).
Bainbridge Island Shoreline Master Program---Public Hearing Draft SMP - March 12, 2012
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