Bluff Recession in the Elwha and Dungeness Littoral Cells, Washington, USA

DAVID S. PARKS1 Washington State Department of Natural Resources, 311 McCarver Road, Port Angeles, WA 98362

Key Terms: Environmental Geology, Land-Use Plan- Washington State, USA, and are the primary source ning, Erosion, Landslides of sediment contributed to mixed sand and gravel beaches in the region (Schwartz et al., 1987; Shipman, 2004; Finlayson, 2006; and Johannessen ABSTRACT and MacLennan, 2007). The spatial and temporal distribution of bluff recession from wave-, wind-, The spatial distribution and temporal variability of precipitation-, and groundwater-induced erosion is retreat rates of coastal bluffs composed of unconsolidated poorly understood and documented for the southern glacial deposits are of interest to landowners who occupy shore of the Strait of Juan de Fuca and has led to bluff-top properties as well as coastal resource managers underestimating the potential hazards to infrastruc- who are responsible for protecting marine habitats such ture (e.g., roads, houses) posed by eroding bluffs as forage fish spawning beaches that are dependent on over time (Figures 1 and 2). Efforts to protect bluff-derived sediments. Assessment of bluff retreat and infrastructure and limit the rates of bluff erosion associated sediment volumes contributed to the nearshore by constructing shoreline revetments have historical- over time is the first step toward development of a coastal ly ignored the physical and ecological effects of sediment budget for bluff-backed beaches using data sediment starvation of beaches caused by shoreline sources including aerial photography (1939, 2001), GPS- hardening (Shipman et al., 2010). The disruption of based beach profile data (2010–2013), and airborne sediment movement from bluffs to beaches has LiDAR (2001, 2012). These data are analyzed in context caused the loss of suitable habitats for critical marine to determine alongshore rates of bluff retreat and species, including forage fish and juvenile salmonids associated volume change for the Elwha and Dungeness (Rice, 2006; Shipman et al., 2010; Shaffer et al., 2012; littoral cells in Clallam County, WA. Recession rates and Parks et al., 2013). The importance of under- from 2001 to 2012 range from 0 to 1.88 m/yr in both drift standing the long-term littoral sediment budget has cells, with mean values of 0.26 ± 0.23 m/yr (N = 152) in been underscored by the recent removal of two dams Elwha and 0.36 ± 0.24 m/yr (N = 433) in Dungeness. on the Elwha River and the subsequent introduction 6 3 Armored sections show bluff recession rates reduced by of approximately 6.4 3 10 m of sediment into the 50 percent in Elwha and 80 percent in Dungeness, relative nearshore environment within the first 2 years to their respective unarmored sections. Dungeness bluffs (between September 2011 and September 2013) (East produce twice as much sediment per alongshore distance et al., 2014; Gelfenbaum et al., in review; and as do the Elwha bluffs (average, 7.5 m3/m/yr vs. 4.1 m3/m/ Warrick et al., in review). yr, respectively). Historical bluff recession rates (1939– Relatively few studies of coastal bluff recession 2001) were comparable to those from 2001–2012. Rates have been completed for the shoreline areas of the derived from short timescales should not be used directly Strait of Juan de Fuca, and the studies that have been for predicting decadal-scale bluff recession rates for completed have used a variety of methods, leading to management purposes, as they tend to represent short- difficulty in comparing results. In the Elwha littoral term localized events rather than long-term sustained cell (herein referred to as ‘‘drift cell’’), the U.S. Army bluff retreat. Corps of Engineers (USACE) completed an evalua- tion of bluff recession rates and sediment volume supply to the nearshore environment as part of an INTRODUCTION environmental assessment for a shoreline armoring and beach nourishment project on Ediz Hook in Port Coastal bluffs are a dominant geomorphic feature Angeles (USACE, 1971). Using Government Land of the shorelines of the Strait of Juan de Fuca, Office and National Geodetic Survey shoreline maps, the USACE estimated a gradual reduction in bluff 1Corresponding author email: [email protected]. recession rates from 1.5 m/yr (1850–1885) to 1.3 m/yr

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Figure 1. (A) Homes threatened by receding bluffs, Dungeness drift cell. (B) Seawall installed at bluff toe to protect Port Angeles City Landfill from bluff retreat, Elwha drift cell.

(1885–1926), decreasing to 1.1 m/yr (1926–1948) and multitude of shoreline armoring projects at the base then to 0.2 m/yr (1948–1970). Each successive of the Elwha bluffs (USACE, 1971). reduction in bluff recession rates since 1930 has been The USACE (1971) study also shows a reduction in attributed to construction and maintenance of a sediment volumes provided by the Elwha bluffs over

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Figure 2. Map of the study area showing direction of net alongshore sediment transport within the Elwha and Dungeness drift cells in Clallam County, WA. time. Prior to the construction of the Elwha Dam in erosion rates of 0–0.08 m/yr using cosmogenic 10Be 1911, the estimated sediment supply from the bluffs concentrations in lag boulders to date shoreline was 2.22 3 105 m3/yr. After construction of the Elwha positions over time scales of 103–104 years. Dam and prior to construction of shoreline armoring In this study, estimates of short- and long-term along the Elwha bluffs in 1929, the estimated bluff recession rates and associated sediment volumes sediment supply from the bluffs was nearly the same, contributed to the Elwha and Dungeness drift cells measuring 2.06 3 105 m3/yr. Between 1929 and 1961, along the Central Strait of Juan de Fuca between when substantial shoreline armoring along the bluffs 1939 and 2012 are derived from historical aerial was installed and maintained, the bluff sediment photography, GPS beach profiles, and airborne supply decreased to 0.73 3 105 m3/yr. Following the LiDAR, and the relative contribution of bluff-derived completion of a major shoreline armoring project sediment supply to the nearshore, in the context of a along the bluffs in 1961, bluff sediment supply was coastal sediment budget recently rejuvenated by the estimated to have further declined to 0.31 3 105 m3/ removal of two dams on the Elwha River, is yr. The reduction of bluff-supplied sediment over this presented. entire time period, 1.91 3 105 m3/yr, represents an 85 percent reduction in the coastal sediment supply to STUDY AREA Ediz Hook (Galster, 1989), which is essentially equivalent to the pre-dam fluvial sediment supply The study area is located on the southern shore of estimated by Randle et al. (1996). the Central Strait of Juan de Fuca near the city of Bluff erosion rates to the east of the Dungeness Port Angeles, WA (Figure 2). The study area is drift cell along the Strait of Juan de Fuca were divided into two distinct shoreline segments that evaluated through land-parcel surveys by Keuler encompass separate but adjacent littoral cells with (1988). Bluff recession rates of up to 0.30 m/yr and bluff-backed beaches: the Elwha bluffs extend along sediment production rates of 1–5 m3/m/yr were the central portion of the Elwha drift cell, and the observed in areas exposed to wave attack associated Dungeness bluffs extend along the western portion of with long fetches. On the west side of Whidbey Island, the Dungeness drift cell (Figure 3). Each drift cell at the eastern limit of the Strait of Juan de Fuca, contains an updrift segment of eroding coastal bluffs Rogers et al. (2012) determined long-term bluff to the west that supply sediment via longshore littoral

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Figure 3. (A) Photograph of the Dungeness bluffs looking west from Dungeness Spit. (B) Photograph of the Elwha bluffs west from Ediz Hook. Note the armoring placed mid-beach in front of the bluffs in photograph B. transport to long spits at the down-drift end to the Dungeness Spit. A fundamental difference between east. the two drift cells is that the Elwha River discharges The Elwha bluff segment is 4.9 km long and into the Strait of Juan de Fuca updrift of the Elwha supplies sediment to Ediz Hook. The Dungeness bluff bluffs, while the Dungeness River empties into the segment is 13.6 km long and supplies sediment to Strait of Juan de Fuca on the lee side of Dungeness

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Spit (Figure 2). Therefore, the Elwha drift cell is 2000; Polenz et al., 2004) and Eocene marine composed of both river- and bluff-derived sediments, sedimentary rocks (Schasse et al., 2000; Schasse and while the Dungeness drift cell is composed of only Polenz, 2002; Schasse, 2003; and Polenz et al., 2004). bluff-derived sediments. Pleistocene glacial deposits occurring within the study The Strait of Juan de Fuca is a wind-dominated area include recessional outwash, glaciomarine drift, marine system that exhibits net easterly longshore and glacial till. sediment transport within the intertidal zone of the Groundwater recharge occurs along the Olympic study area (Galster and Schwartz, 1989; Schwartz et Mountains and discharges into the Strait of Juan de al., 1989; Warrick et al., 2009; and Miller et al., 2011). Fuca. Local groundwater recharge occurs within low- Winds in the Central Strait of Juan de Fuca are elevation glacial landforms adjacent to the coastal dominantly west and northwesterly, with a minor bluffs and discharges at varying elevations on the component of north and northeasterly winds (Miller bluffs controlled by local aquitards (i.e., beds of low- et al., 2011). Therefore, both the Elwha and Dunge- permeability materials composed of dense silt, clay, ness drift cells exhibit net easterly littoral sediment and till) (Drost, 1986; Jones, 1996). transport (USACE, 1971; Galster and Schwartz, The shoreline within the study area exhibits steeply 1989; and Schwartz et al., 1989). sloping to vertical and overhanging coastal bluffs up The wave climate of the Central Strait of Juan de to 80 m high created by changes in relative sea level Fuca is similarly dominated by west to northwest from post-glacial rebound following Cordilleran wind waves and west to northwest swells from the glacial retreat; erosion of the shoreline in the study Pacific Ocean. Maximum wave heights within the area began around 5,400 years before the present time study area range up to 3 m, whereas average heights (Downing, 1983; Dethier et al., 1995; Booth et al., are 0.5 m (USACE, 1971; Gelfenbaum et al., 2009; 2003; Schasse, 2003; Mosher and Hewitt, 2004; and Warrick et al., 2009; and Miller et al., 2011). Polenz et al., 2004). Gelfenbaum et al. (2009) have modeled the distribu- Bluff recession within the study area is dominated tion of significant wave heights within the Central by shallow landsliding in the form of topples, debris Strait of Juan de Fuca, and given a 2-m swell at the avalanches, flows, and slides (Varnes, 1978). Other entrance to the Strait of Juan de Fuca, nearshore types of gravitational failures are also present, wave heights of 1 m are shown throughout the study including stress release fracturing (Bradley, 1963), area, but with significant alongshore variability in cantilever, and Culmann-type (near-vertical planar) wave height due to wave focusing or sheltering and in failures (Carson and Kirkby, 1972). These types of wave direction due to refraction. shallow mass wasting processes are common in sea Tides within the Strait of Juan de Fuca are mixed- cliffs composed of weakly lithified sediments (Hamp- diurnal, with two high and low tides per day. Tidal ton, 2002). Aeolian erosion during dry periods (in the elevations range between 21.0 m and +3.7 m in form of ravel) is also observed. Aerial-, boat-, and elevation (NAVD 88) (Zilkoski et al., 1992; NOAA, ground-based surveys of the study area have deter- 2013). mined the absence of deep-seated (Varnes, 1978) A precipitation gradient exists from west to east landslides consistent with existing geologic mapping within the study area as the result of a rain-shadow (Schasse et al., 2000; Schasse and Polenz, 2002; effect of the Olympic Mountains. Average annual Schasse, 2003; and Polenz et al., 2004). Processes precipitation (1971–2000) in the Elwha drift cell is driving shallow landsliding include over-steepening 660 mm vs. 406 mm in the Dungeness drift cell and subsequent failure of bluffs from wave-induced (Drost, 1986; NCDC, 2014). Maximum rainfall erosion at the bluff-base and the development of high intensities within the Elwha drift cell are 117 mm/hr pore-water pressures within hillslopes during storms. vs. 71 mm/hr in the Dungeness (Drost, 1986; NCDC, Land use above the bluffs varies throughout the 2014). Precipitation occurs primarily as rain, with the study area from dense urban development in the wettest months between October and April and a Elwha drift cell within the City of Port Angeles to seasonal dry period between May and September. native second-growth forest within the Dungeness Freezing temperatures occur within the study area drift cell. Vegetation within the study area ranges between October and May, and snowfall intermit- from dense stands of mature second- and third- tently occurs in the period between November and growth Douglas fir forest to open grass associated April. with urban lawn-scapes. The surficial geology of the study area is domi- The sediment budget of the Elwha drift cell has nantly composed of Pleistocene continental glacial substantially declined as a result of human-induced deposits overlying pre-Fraser non-glacial sediments changes. The construction of coastal revetments associated with an Elwha River source (Schasse et al., began in the Elwha drift cell shortly after the

Environmental & Engineering Geoscience, Vol. XXI, No. 2, May 2015, pp. 129–146 133 Parks construction of two dams on the Elwha River in the determined by analyzing data from historical aerial early 20th century (Galster, 1989). In 1929, a coastal photographs and existing airborne LiDAR data. In revetment was installed between Dry Creek and Ediz order to make comparisons of the bluffs between the Hook to protect an industrial waterline that supplied two data types, two-dimensional cross-shore transects water from the Elwha River to paper mills on Ediz were established in each drift cell at 30-m intervals, Hook. Within 6 years of the placement of coastal except where interrupted by coastal streams or defense works, Ediz Hook began to erode as a result of ravines (Figure 4). Transects extend across the beach the reduction in sediment supply from bluffs (Galster, and up the bluff face, to at least the bluff crest, along 1989). Galster (1989) estimated that in the Elwha drift which retreat distances could be calculated. Bluff cell, 15 percent of the sediment supplying Ediz Hook retreat was measured between consecutive surveys at originated from the Elwha River, and 85 percent was the bluff crest for aerial photos and at selected supplied from coastal bluff erosion prior to construc- elevations across the bluff face for LiDAR data. tion of Elwha River Dams and coastal revetments. Galster (1989) estimated that coastal armoring in the Long-Term Bluff Change Elwha drift cell resulted in an 89 percent reduction of sediment volume supplied to Ediz Hook. In 1975, the Bluff recession rates for 1939–2001 were deter- USACE and the City of Port Angeles armored the mined by calculating the distance between bluff crest shoreline of Ediz Hook and began a program of beach positions on geo-referenced historical aerial photo- nourishment that continues to the current time. In graphs. Prior to analysis, aerial photographs were 2005, the City of Port Angeles constructed a 122 m– scanned, geo-referenced, and imported into ArcGIS long concrete, steel, and rock seawall at the Port v. 10.1 (ESRI, Redlands, CA), and bluff crest Angeles Landfill. Currently, 68 percent of the Elwha positions were digitized for study segment areas bluffs are armored with rip-rap or constructed unobstructed by vegetation. Distances between the seawalls. In contrast, less than 1 percent of the length 1939 and 2001 bluff crest positions were measured at of the Dungeness bluffs is armored. each transect location. In 2012, the Elwha Dam on the Elwha River was Recession rates for 2001–2012 were determined completely removed, and, as of 2014, the Glines from the differences in horizontal position of selected Canyon Dam has also been completely removed, elevations on bluff-face profiles extracted from digital resulting in the delivery of 6.4 3 106 m3 of elevation models (DEMs) available from recent predominantly fine sediment to the nearshore of the airborne LiDAR data sets using methods outlined Elwha littoral cell within the first 2 years since dam in Hapke (2004), Young and Ashford (2009) and removal began in September 2011 (East et al., 2014; Young et al. (2009, 2010, 2011). For this analysis, we Gelfenbaum et al., in review; and Warrick et al., in used a 2001 bare earth DEM (2-m grid) from the review). This sediment volume represents approxi- Puget Sound LiDAR Consortium (PSLC, 2001) that mately 30 percent of the total sediment stored in both covered the entire survey area, 2012 Clallam County reservoirs. It is estimated that within 7–10 years LiDAR (1-m grid; Yotter-Brown and Faux, 2012) for following the complete removal of both Elwha River the Dungeness drift cell, and 2012 LiDAR data (0.5- Dams, the long-term annual sediment contribution m grid) from the U.S. Geological Survey (Woolpert, from the Elwha River to the nearshore will be 2013) for the Elwha drift cell. DEMs were imported approximately 2.5 3 105 m3/yr (Gilbert and Link, into ArcGIS and evaluated using the 3D Analyst 1995; Bountry et al., 2010). toolset. At each transect location a two-dimensional Understanding the relative contribution of bluff topographic profile from the mid-beach to the bluff erosion to the overall sediment budget of the Elwha crest was extracted from each DEM. The net drift cell will help with efforts to manage the long- horizontal distance between the two profiles was term coastal environment once the reservoir sedi- measured at 6-m vertical intervals between the ments released by dam removal have been transport- bottom and top of the bluff face. The difference in ed out of the fluvial network and into the Strait of total cross-sectional area between the 2001 and 2012 Juan de Fuca. topographic profiles was measured and multiplied by a unit width to estimate a volume of sediment lost between the two DEMs. METHODS Statistical evaluation of the data for bluff recession Bluff-Face Change Mapping and sediment volume contributions from the airborne LiDAR DEMs was performed using exploratory data Short- and long-term coastal bluff recession rates analysis methods (Schuenemeyer and Drew, 2011). for the Elwha and Dungeness drift cells were Bluff recession distance values were tested for spatial

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Figure 4. Map showing bluff and beach transect locations for the Elwha bluffs (A) and Dungeness bluffs (B5west, C5east).

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Figure 5. Maximum observed bluff recession rates (m/yr) in the Dungeness drift cell for the time periods 1939–2001 (derived from aerial photography) and 2001–2012 (derived from airborne LiDAR). trend and normalized using a lognormal transforma- 1.5-m data point spacing. The difference values along tion. Summary statistics were then computed using the entire transect were averaged to yield a single the de-trended values. Sources of error include value of average elevation change per transect. The internal error in the LiDAR data acquisition and average elevation change was multiplied by the 20-m processing technique as well as differences in grid size length of the profile and an alongshore unit width of of the LiDAR-derived DEMs. 1 m to yield a volume change per alongshore meter (m3/m) for the 20 m of upland beach. Beach Profile Change Monitoring To assess general trends in beach elevation change RESULTS (m/yr) and to estimate rates of sediment flux on the Bluff-Face Change beaches (m3/m/yr), two-dimensional, cross-shore to- pographic beach profiles at 12 locations, eight along Long-Term Bluff Change the Dungeness bluffs and four along the Elwha bluffs, were surveyed between 2010 and 2013 with a Pro- Observed rates of coastal bluff recession are highly Mark 800 and 200 Real-Time Kinematic Global variable across both drift cells (Figures 5–7). Table 1 Positioning System (RTK-GPS). Elwha and Dunge- provides data results from sections of each drift cell ness drift cell beach profiles were collected in all with unobstructed views of the bluff edge in aerial seasons. Profiles were oriented normal to the slope of photography from 1939 and 2001 and includes the beach, extending from the base of coastal bluffs to identical shoreline reaches used for a comparison of the low water limit. Elevation measurements were rates derived from airborne LiDAR from 2001 and recorded along each transect at horizontal intervals of 2012. The data show a recent decrease in mean approximately 1.5 m. RTK-GPS measurement accu- recession rates in the Elwha drift cell (20.22 m/yr) racy ranged from 1 to 5 cm based on repeat and a slight increase in mean recession rates in recent measurements of fixed control points across the study years in the Dungeness drift cell (+0.1 m/yr). area. Table 2 provides data results that extend along Sediment volume changes were calculated using the the full length of the bluffs in each drift cell. The upper 20 m of each profile, which was the extent of maximum observed rate of recession between 2001 overlap between all surveys. The elevation difference and 2012 in both drift cells was 1.88 m/yr, associated between each pair of profiles was calculated every with housing development in the Dungeness drift cell 0.5 m, with a linear interpolation between the original (Figure 1A) and erosional hotspots along the Port

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Figure 6. Maximum observed bluff recession rates (m/yr) in the Elwha drift cell for the time periods of 1939–2001 (derived from aerial photography) and 2001–2012 (derived from airborne LiDAR).

Figure 7. Box plot of recession rates (m/yr) by drift cell and shoreline type (created in ABOXPLOT; Bikfalvi, 2012). The central line within the box represents the sample median, while the circle represents the sample mean. The upper and lower limits of the box represent the 50th percentile of the population and the whiskers the 75th percentile. Dots beyond the upper and lower whiskers represent outliers of the population.

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Table 1. Recession rates (m/yr) from aerial photography (1939–2001) and airborne LiDAR (2001–2012) for unobstructed bluff-edge reaches of each drift cell.

Minimum Mean Maximum Standard Deviation No. of Drift Cell Period (m/yr) (m/yr) (m/yr) (m/yr) Transects Length (m) Dungeness 1939–2001 0.0 0.40 1.00 0.20 181 5,639 2001–2012 0.1 0.50 0.90 0.17 181 5,639 Elwha 1939–2001 0.2 0.42 0.60 0.10 75 2,469 2001–2012 0.0 0.20 0.55 0.10 75 2,469

Angeles landfill revetment in the Elwha drift cell sediment of the Elwha bluffs, on average (1.03 3 (Figure 1B). The mean recession rate in the Dunge- 105 m3/yr vs. 2.0 3 104 m3/yr, respectively), on an ness was 0.36 m/yr vs. 0.26 m/yr for the Elwha drift annual basis over the 2001–2012 period (Table 4). cell (Table 2) for the 2001–2012 period. When normalized for length, the Dungeness bluffs In both drift cells, armored sections of bluffs contributed approximately 55 percent more sediment showed significantly lower rates of recession than than did the Elwha bluffs to the nearshore (7.5 m3/m/ did unarmored sections: 80 percent less in the yr vs. 4.1 m3/m/yr, respectively) on an annual basis Dungeness drift cell and 50 percent less in the Elwha for the 2001–2012 period (Table 5). drift cell (Table 2 and Figure 7). Unarmored bluff sections demonstrated very similar mean rates of Beach Sediment Volume Changes recession between drift cells: 0.37 m/yr for Dungeness and 0.40 m/yr for Elwha (Table 2 and Figure 7). Annual beach sediment volume changes as well as Unarmored sections of bluffs directly down-drift and the net 3-year change at the 12 transect locations adjacent to armored sections experienced the highest (eight along the Dungeness bluffs; four along the rates of bluff recession in the Elwha drift cell (1.88 m/ Elwha bluffs) are shown in Figure 11 and Tables 6 yr) and higher than mean rates (1.0 m/yr) in the and 7. With the exception of transect EB-1 (where the Dungeness drift cell (Figure 7). effects of sediment supply from the Elwha River are Sediment volumes eroded from bluffs in the Dunge- evident), the general trend in beach sediment volume ness drift cell were almost double those observed in the has been one of net loss over the 3-year period Elwha drift cell per transect (Table 3 and Figures 8– occurring between 2010 and 2013. 10). The mean sediment production rate in the In the Elwha drift cell, annual beach transect 3 Dungeness drift cell was 25.4 m per transect vs. elevation changes ranged from 20.72 (net loss) to 3 13.8 m per transect in the Elwha drift cell. Rates of +1.19 m/yr (net gain) (mean 5 20.13 6 0.52 m/yr). The sediment production from unarmored sections of greatest loss at all Elwha transects occurred during the bluffs were similar between drift cells. Mean values 2010–2011 period. In the Dungeness drift cell, annual for sediment production from unarmored sections of beach transect elevation changes ranged from 21.05 m/ 3 bluffs in the Dungeness drift cell were 25.8 m per yr to +0.22 m/yr (mean 5 20.19 6 0.29 m/yr). transect vs. 22.0 m3 per transect for the Elwha drift cell (Table 3). Sediment production rates for armored sections of bluffs were twice as high in the Elwha drift DISCUSSION 3 cell (11.9 m per transect) compared to the Dungeness Bluff Recession Rates drift cell (5.8 m3 per transect) (Table 3 and Figure 10). At the drift cell scale, the Dungeness bluffs Rates of bluff recession observed in this study in produced approximately five times the volume of the Elwha drift cell generally agree with rates

Table 2. Recession rates (m/yr) by drift cell and shoreline type, 2001–2012.

Minimum Mean Maximum Standard Deviation No. of Drift Cell Shoreline Type (m/yr) (m/yr) (m/yr) (m/yr) Transects Length (m) Dungeness Unarmored 0.0 0.37 1.88 0.79 423 13,320 Armored 0.0 0.08 0.46 0.40 10 305 All 0.0 0.36 1.88 0.24 433 13,625 Elwha Unarmored 0.0 0.40 1.88 1.30 60 1,829 Armored 0.0 0.21 0.58 0.40 92 3,048 All 0.0 0.26 1.88 0.23 152 4,877

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Table 3. Sediment volume contribution per transect (m3) by drift cell and shoreline type, 2001–2012.

Standard Drift Cell Shoreline Type Minimum (m3) Mean (m3) Maximum (m3) Deviation (m3) No. of Transects Length (m) Dungeness Unarmored 0.0 25.8 163.3 24.3 423 13,320 Armored 0.0 5.8 9.6 3.8 10 305 All 0.0 25.4 124.8 31.7 433 13,625 Elwha Unarmored 0.0 22.0 143.6 30.1 60 1,829 Armored 0.0 11.9 41.2 7.9 92 3,048 All 0.0 13.8 159.9 35.9 152 4,877 measured by the USACE (USACE, 1971) in the commercial construction activities adjacent to the Elwha drift cell in the decade between 1960 and1971, coastal bluffs. Given a typical design life of a single but they are elevated over those observed by Keuler family home of 100 years, applying the observed (1988) in the Dungeness drift cell and are substan- mean bluff recession rates (Table 1) provides a tially higher than the long-term rates observed by minimum setback distance between a structure and Rogers et al. (2012) for Eastern Strait of Juan de Fuca the edge of the bluff of 42 m in the Elwha drift cell shorelines. Rates of bluff erosion documented in this and of 40 m in the Dungeness drift cell, based on study are also consistent with rates observed along the mean long-term (1939–2001) recession rates. It should west coast of the United States exposed to open-ocean be noted that these rates of observed bluff recession wave climates (Collins and Sitar, 2008; Pettit et al., fall closely in line with estimates of 0.47 m/yr 2014). Rates of bluff recession observed between 2001 published for the Elwha drift cell by Polenz et al. and 2012 may represent higher-than-average erosion (2004) and likely represent the long-term post-glacial rates due to high storm frequency and intensity average bluff recession rate for glacial deposits on the occurring during this period: two time intervals, the south shore of the Central Strait of Juan de Fuca. winters of 2007 and 2009, represent two of the wettest Extending past observed bluff recession rates into and windiest periods on record for this location the future is likely a simplistic and inaccurate method (NCDC, 2014). Additionally, the 2001–2011 period to determine future bluff recession (Hapke and Plant, experienced four high-tide events that exceeded the 2010). Probabilistic methods of predicting bluff 50-year recurrence interval for extreme high water erosion (Lee et al., 2001; Walkden and Hall, 2005; levels in the Central Strait of Juan de Fuca (NOAA, and Hapke and Plant, 2010) that accommodate 2013). spatial and temporal variability could be applied to Bluff recession rates observed in the Dungeness and the Dungeness and Elwha drift cells and would likely Elwha drift cells in this study have immediate be more accurate than using hindcast observations application to land-use planning for residential and of bluff recession to predict future erosion rates.

Figure 8. Sediment volume (m3) per transect in the Dungeness drift cell (2001–2012).

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Figure 9. Sediment volume (m3) per transect in the Elwha drift cell (2001–2012).

Figure 10. Box plot of sediment volume contributions (m3/transect) by drift cell and shoreline type (created in ABOXPLOT; Bikfalvi, 2012). The central line within the box represents the sample median, while the circle represents the sample mean. The upper and lower limits of the box represent the 50th percentile of the population and the whiskers the 75th percentile. Dots beyond the upper and lower whiskers represent outliers of the population.

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Table 4. Annual sediment volume contribution (m3/yr) by drift Comparing the sediment production rates between cell, 2001–2012. the Dungeness and Elwha bluffs demonstrates the level of impairment within the Elwha drift cell. When Mean Mean + 1 Standard No. of Drift Cell (m3/yr) Deviation (m3/yr) Transects Length (m) normalized for drift cell length, the Elwha bluffs produce 56 percent less sediment volume than do the Dungeness 103,000 232,000 433 13,625 Dungeness bluffs on an annual basis. Comparing the Elwha 20,000 49,000 152 4,877 measured rates of sediment production from bluffs (Table 5) versus sediment volume change in beach However, the data necessary to employ these proce- transects (Tables 6 and 7 and Figure 11) demon- dures (e.g., wave and tidal height distributions along strates the imbalance in the sediment supply relative the bluffs) are not currently available. to available sediment transport. In most years, the amount of available sediment volume contributed from bluffs to the beach is substantially less than the Sediment Volume Change average rate of sediment loss, leading to beach Annual sediment volume contributions within the lowering and resulting in accelerated bluff erosion. Elwha drift cell from this study (2.0 3 104 m3/yr; 4 3 Table 4) are consistent with the flux of 3.1 3 10 m / Management Implications yr determined by USACE (1971). The calculated length-normalized rate of 4.1 m3/m/yr for the Elwha Bluff recession rates were shown to vary depending drift cell is substantially less (255 percent) than the on the time of measurement and length of time rate observed (7.5 m3/m/yr) for the Dungeness drift observed. It is not appropriate to extrapolate short- cell, which is consistent with a previous study by term measurements into long-term rates, especially if Keuler (1988) that measured sediment contribution the length of measurement is less than the time span rates for the exposed areas of the Strait of Juan de of the rate being reported (e.g., producing an annual Fuca ranging between 6.0 and 12.0 m3/m/yr. rate from ,1 year of observation). For instance, a Bluff-supplied sediment volume estimates for the measurement taken over a month when there was a Elwha drift cell from this study can help refine the large bluff failure could result in large overestimates coastal sediment budget post–dam removal. Since of bluff recession on an annual basis if there was no shore-protection works in the Elwha drift cell will further change for the remainder of the year. remain after the Elwha Dams have been removed, a Moreover, using the maximum measured recession significant component of the Elwha drift cell sediment distance to calculate an annual recession rate will budget will remain impaired after the sediment supply result in an even-greater overestimate and could give from the Elwha River has been restored. a false impression of how much the bluff is actually Randle et al. (1996) estimates that the pre-dam retreating. The maximum recession distance is mea- fluvial sediment contribution to the Strait of Juan de sured for a specific point along the bluff and may not Fuca was about 1.9 3 105 m3/yr. In the Elwha drift represent the trends observed over the larger area. It cell, the current upper estimate of annual sediment would be more correct to calculate a mean bluff volume contribution to the nearshore from bluff recession distance for a given area measured over a erosion is approximately 2.0 3 104 m3/yr–4.9 3 long period of time (i.e., years to decades). The long- 104 m3/yr (Table 4), or about 11–26 percent of the term rates should then be qualified with the amount pre-dam annual sediment contribution from the of recession that may occur during a given event (e.g., Elwha River. The current annual sediment volume the average maximum recession distance). As an contribution from bluff erosion in the Elwha drift cell example, for land-use management, it would be more represents a 90 percent reduction from the 1911 pre- appropriate to use a long-term mean recession rate armoring estimate (2.2 3 105 m3/yr; USACE, 1971) over the horizon of interest to obtain a setback but is roughly approximate to the 1960 post-armoring distance, with an added buffer based on event-scale estimate (3.1 3 104 m3/yr; Galster, 1989). recession.

Table 5. Annual length-normalized sediment contribution (m3/m/yr) by drift cell, 2001–2012.

Mean + 1 Standard Drift Cell Mean (m3/m/yr) Deviation (m3/m/yr) Maximum (m3/m/yr) No. of Transects Length (m) Dungeness 7.5 17.0 11.3 433 13,625 Elwha 4.1 10.0 14.5 152 4,877

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Figure 11. Length-normalized sediment volume change (m3/m) in the highest 20 m of each beach topographic profile during four winter-to- winter time intervals. EB-1 through BL-1 were winter surveys; BL-2 through DB-4 were summer surveys. Note that intervals 1–3 are annual, whereas interval 4 spans 3 years.

It should be emphasized that the bluff recession are more conducive to land-use zoning, buffers, and distances reported in this study are derived from development setbacks. The bluff-face profile method selected elevations across the bluff-face profile, has the potential to accentuate the localized erosion which may not be seen by the homeowner at the signals due to a lack of continuity along the bluff to bluff top. While the trends are not likely to enable alongshore averaging commensurate with the significantly change, results will differ according to observed signals of change obtained at finer scale the methods used to analyze bluff-face change. along the bluff face. Other methods of calculating bluff recession dis- While land-use planners and coastal managers are tances (e.g., contour change analysis, volume change in need of long-term erosion rates for prudent analysis) are expected to provide different results resource management, property owners experience than the profile-based methods used herein, and the localized erosion and tend to be most interested in potential to produce alongshore averaging of bluff and concerned about the magnitude of bluff recession recession rates over appropriate alongshore length occurring along relatively small increments of space scales may result in less spatially variable rates that along their bluff-top property boundary.

Table 6. Beach topographic profile sediment volume changes for the Elwha drift cell. Note that the right-most column is net change between 2010 and 2013, while all others are annual intervals.

2010–2011 2011–2012 2012–2013 2010–2013 Volume Change Change Rate Volume Change Change Rate Volume Change Change Rate Volume Change Change Rate Profile (m3/m) (m/yr) (m3/m) (m/yr) (m3/m) (m/yr) (m3/m) (m/yr) EB-1 213.54 20.69 2.42 0.12 24.89 1.19 13.77 0.23 EB-2 27.77 20.40 20.17 20.01 5.82 20.28 213.77 20.23 EB-3 212.33 20.66 1.87 0.09 22.06 20.11 212.66 20.22 EB-4 211.88 20.72 0.41 0.02 21.52 20.08 212.98 20.23 Average 211.38 20.62 1.13 0.06 3.87 0.18 26.41 20.11

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Table 7. Beach topographic profile sediment volume changes for the Dungeness drift cell. Note that the right-most column is net change between 2010 and 2013, whereas all others are annual intervals.

2010–2011 2011–2012 2012–2013 2010–2013 Volume Change Change Rate Volume Change Change Rate Volume Change Change Rate Volume Change Rate Profile (m3/m) (m/yr) (m3/m) (m/yr) (m3/m) (m/yr) Change (m3/m) (m/yr) BC-1 23.87 20.20 25.37 20.24 22.63 20.16 211.86 20.20 BC-2 2.83 0.15 27.85 20.34 1.02 0.06 24.01 20.07 BL-1 210.47 20.43 28.57 20.38 23.67 20.23 222.72 20.36 BL-2 24.38 20.22 25.22 20.29 4.73 0.20 24.88 20.08 DB-1 28.56 20.43 22.07 20.12 21.22 20.05 211.84 20.20 DB-2 1.11 0.06 24.30 20.24 0.76 0.03 22.42 20.04 DB-3 212.23 20.79 0.48 0.03 2.02 0.08 29.73 20.17 DB-4 219.44 21.05 21.67 20.09 3.10 0.14 218.01 20.31 Average 26.88 20.36 24.32 20.21 0.51 0.01 210.68 20.18

Chronic sediment supply deficits in the Elwha drift were the result of individual medium-scale landslides. cell due to shoreline armoring have resulted in The presence of shoreline armoring is a controlling significant habitat impairment on intertidal beaches factor on the rate of bluff recession, with armored for forage fish and juvenile salmonids (Shaffer et al., bluffs showing a reduced recession rate compared 2012; Parks et al., 2013). The removal of the two with unarmored bluffs. The volume of sediment Elwha River Dams will restore a significant compo- produced by a unit length of unarmored bluff nent of the Elwha littoral cell sediment supply. It is shoreline is greater than that of armored bluffs by currently unknown to what degree and over what factors of two (Elwha) and five (Dungeness), respec- timescale Elwha River sediments will be stored on tively. intertidal beaches within the Elwha drift cell. Local Sediment volumes contributed by bluffs in the shoreline managers have an unprecedented opportu- Elwha drift cell between 2001 and 2012 represent 11– nity to optimize storage of Elwha River sediments on 29 percent of the estimated fluvial sediment contri- intertidal beaches through implementation of selected bution to the nearshore from the Elwha River prior to shoreline armoring removal and large-woody debris dam construction in 1911. Annual sediment volumes placement strategies prior to the complete delivery of contributed by bluffs in the Elwha drift cell between Elwha River reservoir sediments into the intertidal 2001 and 2012 represent approximately 8–20 percent environment over the next 5–7 years. of the current estimate (Gilbert and Link, 1995; In contrast to the impaired habitat function of Bountry et al., 2010) of the long-term, post-dam Elwha drift cell due to sediment starvation from removal annual fluvial sediment contribution to the shoreline armoring and Elwha River Dams, the nearshore from the Elwha River of about 2.5 3 Dungeness drift cell exhibits less than 1 percent by 105 m3/yr. length armored shoreline and highly functioning This study confirms that alteration to bluffs, in this forage fish spawning habitat (Shaffer et al., 2012; case armoring, drastically affects bluff recession rates Parks et al., 2013). The intact littoral sediment and sediment volume contributions to the nearshore. supply processes from coastal bluff erosion within Armored sections of bluffs showed significantly lower the Dungeness drift cell are maintaining suitable rates (280 percent, Dungeness; 253 percent, Elwha) forage fish habitat (Parks et al., 2013) and expanding of recession than did unarmored sections. Unarmored the Dungeness Spit through sediment deposition sections of bluffs directly down-drift and adjacent to (Schwartz et al., 1987). armored sections experienced the highest rates of bluff recession in the Elwha drift cell (1.88 m/yr) and CONCLUSIONS higher than mean rates (1.0 m/yr) in the Dungeness drift cell. Rates of coastal bluff recession in the Dungeness It was beyond the scope of this study to determine and Elwha drift cells over the 1939–2012 period were why there was a difference in sediment production highly variable in space and time and ranged between rates between the Elwha and Dungeness drift cells. 0.31 m/yr and 1.88 m/yr. Differences between Geology, groundwater effects, wave-approach angle, maximum near-term bluff erosion rates observed wave energy, and land use are all possible factors from 2001–2012 LiDAR and long-term (1939–2001) explaining the observed differences, and these should observations from digitized historical photography be further investigated in future studies.

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While wave run-up and erosion at the base of dynamics, and measurement of these parameters coastal bluffs is a dominant driving factor of erosion combined with high-resolution bluff-face topography throughout both drift cells, portions of each drift cell and differences over time will enable the development also exhibited erosion in the upper one-third of the of improved process-based bluff erosion models (Lee bluff profile driven by a combination of precipitation, et al., 2001; Castedo et al., 2012). local groundwater discharge, and relatively permeable glacial strata overlying impermeable glacial strata. ACKNOWLEDGMENTS The observed upper-bluff erosion driven by ground- water and precipitation appears to be spatially and This study benefited from discussions with Anne temporally isolated from wave erosion, especially Shaffer (Coastal Watershed Institute), Jon Warrick where shore protection works are in place, and this (USGS), and Hugh Shipman (WDOE) on coastal trend will continue whether the shoreline is armored processes and sediment budgets along the Central or not. Strait of Juan de Fuca. Jesse Wagner and Wade At present, it remains challenging to make reliable Raynes (Western Washington University) and Clinton projections of bluff recession that may guide devel- Stipek (University of Washington) provided field and opment setback distances for the future, given the technical support. Western Washington University coarse resolution of a multi-decadal interval (aerial and Peninsula College provided field equipment and photos for 1939–2001) and only one higher-resolution student interns. Anne Shaffer (Coastal Watershed decadal interval (airborne LiDAR data for 2001– Institute) provided vital overall support, coordination, 2012). The combination of chronic recession rates and and integration with other project components. event-based erosion magnitudes is important for Diana McCandless, Washington Department of decision makers, and the most reliable rates will Ecology Coastal Mapping Program, provided analy- come from a longer-term high-resolution data set that sis of beach erosion data. Heather Baron, Matt must be developed over time. Brunengo, Kerry Cato, Wendy Gerstel, Amanda The results of this study provide estimates for Hacking, Michael W. Hart, George Kaminsky, and minimum setback distances between structures and Keith Loague provided helpful reviews. bluff edges based on long-term mean recession rates We want to sincerely thank Ruth Jenkins, John measured over the scale of an entire drift cell. This Warrick, Chris Saari, Paul Opionuk, Pam Lowry, type of information provides the scientific basis that Connie and Pat Schoen, Hearst Cohen, Malcolm land-use planners and government regulators need Dudley, Nippon Paper, and the Lower Elwha in order to develop sound long-term management S’Klallam Tribe for access across private property. policies for bluff development. Dungeness National Wildlife Refuge personnel and Recession distances measured for a specific point volunteers provided access and transportation. along the bluff may not represent the trends observed Student interns were funded by the U.S. Environ- over the larger drift-cell area and over a longer period mental Protection Agency under grant number PC- of time. It would be more correct to calculate a mean 00J29801-0 awarded to the Washington Department bluff recession distance for a given area measured of Fish and Wildlife (contract number 10-1744) and over a long period of time (i.e., years to decades). The managed by the Coastal Watershed Institute. Fund- long-term rates should then be qualified with the ing for student interns and GPS equipment used to amount of recession that may occur during a given collect beach profiles were provided by the Clallam event (e.g., the average maximum recession distance). County Marine Resources Committee and by the As an example, for land-use management, it would be Environmental Protection Agency grant listed above. more appropriate to use a long-term mean recession Any opinions, findings and conclusions, or recom- rate over the horizon of interest to obtain a setback mendations expressed in this material are those of the distance with an added buffer based on event-scale author and do not necessarily reflect the views of the recession. Environmental Protection Agency or the Washington Repeat surveys performed at relatively short Department of Natural Resources. intervals would enable a better determination of the relative importance of a variety of mechanisms REFERENCES contributing to bluff erosion, such as surface runoff (and associated land-clearing and development prac- BIKFALVI, 2012, ABOXPLOT, Advanced Boxplot Routine for tices), wind, precipitation, groundwater discharge, MATLAB: Electronic document, available at http://alex. bikfalvi.com/research/advanced_matlab_boxplot/ soil saturation, wave height and direction, total water BOOTH, D. B.; TROOST, K. G.; CLAGUE, J. J.; AND WAITT, R. B., level, beach width and elevation, and littoral sediment 2003, The Cordilleran ice sheet: Development Quaternary supply. All of these factors play a role in bluff retreat Science, Vol. 1, pp. 17–43.

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BOUNTRY, J. A.; FERRARI, R.; WILLE, K.; AND RANDLE, T. J., 2010, Cliffs—Status and Trends: U.S. Geological Survey Profes- 2010 Survey Report and Area-Capacity Tables for Lake Mills sional Paper 1693, pp. 39–50. and Lake Aldwell on the Elwha River, Washington: U.S. HAPKE,C.J.AND PLANT, N., 2010, Predicting coastal cliff erosion Department of Interior, Bureau of Reclamation, Technical using a Bayesian probabilistic model: Marine Geology, Service Center, Report No. SRH-2010-23, 66 p. Vol. 278, pp. 140–149. BRADLEY, W. C., 1963, Large-scale exfoliation in massive JOHANNESSEN,J.AND MACLENNAN, A., 2007, Beaches and Bluffs of sandstones of the Colorado Plateau: Geological Society Puget Sound: Puget Sound Nearshore Partnership Report America Bulletin, Vol. 74, pp. 519–528. No. 2007-04, Seattle District, U.S. Army Corps of Engineers, CARSON,M.A.AND KIRKBY, M. J., 1972, Hillslope Form and Seattle, WA, 34 p. Processes: Cambridge University Press, Cambridge, MA, JONES, M. A., 1996, Delineation of Hydrogeologic Units in the 475 p. Lower Dungeness River Basin, Clallam County, Washington: CASTEDO, R.; MURPHY, W.; LAWRENCE, J.; AND PAREDES, C., 2012, U.S. Geological Survey, Water Resources Investigation A new process-response coastal recession model of soft rock Report 95-4008, 11 p. cliffs: Geomorphology, Vol. 177–178, pp. 128–143. KEULER, R. F., 1988, Map Showing Coastal Erosion, Sediment COLLINS,B.D.AND SITAR, N., 2008, Processes of coastal bluff Supply, and Longshore Transport in the Port Townsend 30-by- erosion in weakly lithified sands, Pacifica, California, USA: 60-Minute Quadrangle, Puget Sound Region, Washington: Geomorphology, Vol. 97, No. 3–4, pp. 483–501. U.S. Geologic Survey Miscellaneous Investigation Map I- DETHIER, D. P.; PESSL, F., JR.; KEULER, R. F.; BALZARINI, M. A.; 1198-E, scale 1:100,000. AND PEVEAR, D. R., 1995, Late Wisconsinan glaciomarine LEE, E. M.; HALL, J. W.; AND MEADOWCROFT, I. C., 2001, Coastal deposition and isostatic rebound, northern Puget Lowland, cliff recession: The use of probabilistic prediction methods: Washington: Geological Society America Bulletin, Vol. 107, Geomorphology, Vol. 40, pp. 253–269. No. 11, pp. 1288–1303. MILLER, I. M.; WARRICK, J. A.; AND MORGAN, C., 2011, DOWNING, J., 1983, The Coast of Puget Sound: Its Processes and Observations of coarse sediment movements on the mixed Development: University of Washington Press, Seattle, WA, beach of the Elwha Delta, Washington: Marine Geology, 126 p. Vol. 282, No. 3–4, pp. 201–214. DROST, B. W., 1986, Water Resources of Clallam County, MOSHER,D.C.AND HEWITT, A. T., 2004, Late Quaternary Washington: U.S. Geological Survey Water Resources deglaciation and sea-level history of eastern Juan de Fuca Investigations Report 83-4227, 263 p. Strait, Cascadia: Quaternary International, Vol. 121, pp. 23– EAST, A. E.; PESS, G. R.; BOUNTRY, J. A.; MAGIRL, C. S.; RITCHIE, 39. A. C.; LOGAN, J. B.; RANDLE, T. J.; MASTIN, M. C.; MINEAR, NATIONAL CLIMATE DATA CENTER (NCDC), 2014, Climate J. T.; DUDA, J. J.; LIERMANN, M. C.; MCHENRY, M. L.; Summaries for Port Angeles and Sequim, Washington: BEECHIE, T. J.; AND SHAFROTH, P. B., 2014, Large-scale dam Electronic document available at http://www.ncdc.noaa.gov/ removal on the Elwha River, Washington, USA: River NATIONAL OCEANIC and ATMOSPHERIC ADMINISTRATION (NOAA), channel and floodplain geomorphic change: Geomorphology: 2013, Tidal Data for Port Angeles, Washington, Station 9444090; In Press, doi:0.1016/j.geomorph.2014.08.028 Electronic document available at http://tidesandcurrents.noaa. FINLAYSON, D., 2006, The Geomorphology of Puget Sound Beaches: gov/stationhome.html?id59444090 Puget Sound Nearshore Partnership Report No. 2006-02, Washington Sea Grant Program, University of Washington, PARKS, D.; SHAFFER, A.; AND BARRY, D., 2013, Nearshore drift-cell Seattle, WA, 45 p. sediment processes and ecological function for forage fish: Implications for ecological restoration of impaired Pacific GALSTER, R. W., 1989, Ediz Hook—A Case History of Coastal Erosion and Mitigation. Engineering Geology in Washington, Northwest marine ecosystems: Journal Coastal Research, Vol. 2: Washington Division of Geology and Earth Vol. 29, No. 4, pp. 984–997. Resources Bulletin 78, Washington Department of Natural PETTIT, M. M.; THOMAS, M. A.; AND LOAGUE, K., 2014, Retreat of Resources, Olympia, WA, pp. 1177–1186. a coastal bluff in Pacifica, California: Environmental Engi- neering Geoscience, Vol. 20, No. 2, pp. 153–162. GALSTER,R.W.AND SCHWARTZ, M. L., 1989, Ediz Hook—A case history of coastal erosion and rehabilitation. In Schwartz, POLENZ, M.; WEGMANN, K. W.; AND SCHASSE, H. W., 2004, M. L. and Bird, E. C. F. (Editors), Artificial beaches: Journal Geologic Map of the Elwha and Angeles Point 7.5-Minute Coastal Research, Special Issue 6, pp. 103–113. Quadrangles, Clallam County, Washington: Washington GELFENBAUM, G.; STEVENS, A.; ELIAS, E.; AND WARRICK, J., 2009, Division of Geology and Earth Resources, Open File Report Modeling sediment transport and delta morphology on the 2004-14. dammed Elwha River, Washington State, USA: Coastal PUGET SOUND LIDAR CONSORTIUM (PSLC), 2001, Topographic Dynamics: Paper No. 109, 15 p. LiDAR: PSLC, Clallam County, WA. GELFENBAUM, G. R.; STEVENS, A.; MILLER, I.; AND WARRICK, J. A., RANDLE, T. J.; YOUNG, C. A.; MELENA, J. T.; AND OUELLETTE, 2014, Large-scale dam removal on the Elwha River, E. M., 1996, Sediment Analysis and Modeling of the River Washington, USA: Coastal geomorphic change: Geomor- Erosion Alternative: U.S. Bureau of Reclamation, Pacific phology: in review. Northwest Region, Elwha Technical Series PN-95-9, 138 p. GILBERT,J.AND LINK, R. A., 1995, Alluvium Distribution in Lake RICE, C. A., 2006, Effects of shoreline modification on a northern Mills, Glines Canyon Project and Lake Aldwell, Elwha Project, Puget Sound beach: Microclimate and embryo mortality in Washington: U.S. Department of Interior, Elwha Technical surf smelt (Hypomesus pretiosus): Estuaries Coasts, Vol. 29, Series PN-95-4, 60 p. No. 1, pp. 63–71. HAMPTON, M. A., 2002, Gravitational failure of sea cliffs in weakly ROGERS, H. E.; SWANSON, T. W.; AND STONE, J. O., 2012, Long- lithified sediment: Environmental Engineering Geoscience, term shoreline retreat rates on Whidbey Island, Washington, Vol. 8, No. 3, pp. 175–191. USA: Quarternary Research: doi:10.1016/j.yqres.2012.06.001 HAPKE, C., 2004, The measurement and interpretation of coastal SCHASSE, H. W., 2003, Geologic Map of the Washington Portion of cliff and bluff retreat. In Hampton, M. and Griggs, G. the Port Angeles 1:100,000 Quadrangle: Washington Division (Editors), Formation, Evolution, and Stability of Coastal of Geology and Earth Resources, Open File Report 2003-6,

Environmental & Engineering Geoscience, Vol. XXI, No. 2, May 2015, pp. 129–146 145 Parks

Washington Department of Natural Resources, Olympia, Report 176, Transportation Research Board, National WA. Academy of Sciences, National Research Council, Washing- SCHASSE,H.W.AND POLENZ, M., 2002, Geologic Map of the Morse ton, DC, pp. 11–33. Creek 7.5-Minute Quadrangle, Clallam County, Washington: WALKDEN,M.J.A.AND HALL, J. W., 2005, A predictive Mesoscale Washington Division of Geology and Earth Resources, Open model of the erosion and profile development of soft rock File Report 2002-8, Washington Department of Natural shores: Coastal Engineering, Vol. 52, pp. 535–563. Resources, Olympia, WA. WARRICK, J. A.; BOUNTRY, J. A.; EAST, A. E.; MAGIRL, C. S.; SCHASSE, H. W.; POLENZ, M.; AND WEGMANN, K. W., 2000, RANDLE, T. J.; GELFENBAUM, G. R.; RITCHIE, A. C.; PESS, Geologic Map of the Carlsborg 7.5-Minute Quadrangle, G. R.; LEUNG, V.; AND DUDA, J. J., 2014, Large-scale dam Clallam County, Washington: Washington Division of Geol- removal on the Elwha River, Washington, USA: Source to ogy and Earth Resources, Open File Report 2000-7, sink sediment budget and synthesis. Geomorphology:in Washington Department of Natural Resources, Olympia, review. WA. WARRICK, J. A.; GEORGE, D. A.; GELFENBAUM, G.; RUGGIERO, P.; SCHUENEMEYER,J.H.AND DREW, L. J., 2011, Statistics for Earth KAMINSKY, G. M.; AND BEIRNE, M., 2009, Beach morphology and Environmental Scientists: John Wiley & Sons, Inc., and change along the mixed grain-size delta of the dammed Hoboken, NJ, 407 p. Elwha River, Washington: Geomorphology, Vol. 111, pp. 136– SCHWARTZ, M. L.; FABBRI, P.; AND WALLACE, R. S., 1987, 148. Geomorphology of Dungeness Spit, Washington, USA: WOOLPERT,INC., 2013, Elwha River, WA LiDAR, United States Journal Coastal Research, Vol. 3, No. 4, pp. 451–455. Geological Survey (USGS). Contract No.: G10PC00057. SCHWARTZ, M. L.; WALLACE, R. S.; AND JACOBSEN, E. E., 1989, Net Woolpert, Inc.)Englewood, CO, 11 p. shore-drift in Puget Sound, Engineering Geology in Wash- YOTTER-BROWN,C.W.AND FAUX, R., 2012, LiDAR Remote ington, Vol. 2, Olympia, WA: Washington Division Geology Sensing, Jefferson and Clallam Counties, Washington: Puget Earth Resources Bulletin 78: Washington Department of Sound LiDAR Consortium, Seattle, WA, 29 p. Natural Resources, pp. 1137–1146. YOUNG,A.P.AND ASHFORD, S. A., 2007, Quantifying sub-regional SHAFFER, J. A.; CRAIN, P.; KASSLER, T.; PENTTILA, D.; AND BARRY, seacliff erosion using mobile terrestrial LiDAR: Shore Beach, D., 2012, Geomorphic habitat type, drift cell, forage fish and Vol. 75, No. 3, pp. 38–43. juvenile salmon; are they linked? Journal Environmental YOUNG, A. P.; GUZA, R. T.; O’REILLY, W. C.; FLICK, R. E.; AND Science Engineering, Vol. 1, No. 5a, pp. 688–703. GUTIERREZ, R., 2011, Short-term retreat statistics of a slowly SHIPMAN, H., 2004, Coastal bluffs and sea cliffs on Puget Sound, eroding coastal cliff: Natural Hazards Earth System Sciences, Washington. In Hampton, M. A. and Griggs, G. B. (Editors), Vol. 11, pp. 205–217. Formation, Evolution and Stability of Coastal Cliffs—Status YOUNG, A. P.; OLSEN, M. J.; DRISCOLL, N.; GUTIERREZ, R.; GUZA, and Trends: U.S. Geological Survey Professional Paper 1693, R. T.; FLICK, R. E.; JOHNSTONE, E.; AND KUESTER, F., 2009, 123 p. Comparison of airborne and terrestrial LiDAR estimates of SHIPMAN, H.; DETHIER, M. N.; GELFENBAUM, G.; FRESH, K. L.; AND seacliff erosion in Southern California: Photogrammetric DINICOLA, R. S. (Editors), 2010, Puget Sound shorelines and Engineering Remote Sensing, Vol. 76, No. 4, pp. 421–426. the impacts of armoring: Proceedings of the State of the YOUNG, A. P.; RAYMOND, J. H.; SORENSON, J.; JOHNSTONE, E. A.; Science Workshop, May 2009, Menlo Park, CA: U.S. DRISCOLL, N. W.; FLICK, R. E.; AND GUZA, R. T., 2010, Geological Survey Scientific Investigations Report 2010- Coarse sediment yields from seacliff erosion in the Oceanside 5254, 262 p. Littoral Cell: Journal Coastal Research, Vol. 26, No. 3, U.S. ARMY CORPS OF ENGINEERS (USACE), 1971, Report on Survey pp. 580–585. of Ediz Hook for Beach Erosion and Related Purposes. Port ZILKOSKI, D. B.; RICHARDS, J. H.; AND YOUNG, G. M., 1992, Angeles, Washington: Department of the Army, Seattle Results of the general adjustment of the North American District, Corps of Engineers, 96 p. vertical datum of 1988, (NAVD 88): American Congress VARNES, D. J., 1978, Slope movement types and processes. In Surveying Mapping, Surveying Land Information Systems, Clark, M. (Editor), Landslide Analysis and Control: Special Vol. 52, No. 3, pp. 133–149.

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