OPR-R300-KR-16Etolin StraitBering SeaTerraSond LimitedH129496Registry Instructions4 NM East of Cape CorwinAlaskaUnited States400002016Andrew OrthmannNavigable Area2016-07-202016-07-172016-08-05Multibeam Echo SounderSide Scan SonarmetersWGS84UTCPacific Hydrographic BranchContractorA navigable area survey (H12949) was conducted in the area 4 NM East of Cape Corwin, Alaska, in accordance with the NOAA, National Ocean Service, Statement of Work (SOW), OPR-R300-KR-16, dated July 15th, 2016 and Hydrographic Survey Project Instructions dated July 20th, 2016. Hydrographic survey data was acquired from July 17th through August 5th, 2016. Tidal data was collected from mid-June through late September, 2016. Note that this survey area was part of a modification to the original task order (work instructions dated May 12th) and added four additional survey sheets to the four previously assigned. An additional contract modification, "Mod2", issued February 17th, 2017, extended the deliverables submission deadline to March 13th, 2017, due to delays associated with issuance of the final TCARI tide grid. The survey area is located at the south approach to Etolin Strait, a navigable passage off of the southwest Alaska coast. Nunivak Island lies to the west, with Nelson Island and mainland Alaska to the east. This relatively remote region of the Arctic is covered or heavily influenced by sea ice for a large portion of the year, presenting a limited ice-free season with open navigable water from approximately June through October. Vessel traffic in the region primarily consists of barges serving nearby communities or transiting through the area to other points along Alaska's west and north coasts, bringing fuel and supplies, as well as some freighter traffic. Nunivak Island provides some of the only protection available for vessels transiting Alaska's southwest coast, a region that frequently experiences inclement weather and poor sea conditions. Traffic is relatively sparse, but has been increasing in recent years along with economic and scientific interest in the Arctic. Nearby communities are small and primarily subsistence-based. The region is not connected to the road system and communities depend on air services for connections to Bethel and on to Anchorage. No facilities exist nearby for supporting, or servicing larger vessels, with Bethel (approximately 200 NM transit) and Nome (approximately 250 NM transit) the closest port options for fueling, or limited services. During this survey--which utilized a 105' research vessel--Bethel was used for resupply, largely due to a more protected transit route. However, larger or deeper drafted vessels may favor Nome. TerraSond conducted multibeam echosounder (MBES) and side scan sonar (SSS) operations in the area in accordance with the project instructions, which specified areas requiring complete coverage (100% SSS with concurrent complete coverage MBES), and areas requiring set-spaced MBES-only. Other requirements included tidal data collection and bottom sampling. 60.087031165.68670859.816436165.299453Survey extents and overview.SupportFiles\1_H12949_SurveyExtents.jpgSurvey Limits were acquired in accordance with the requirements in the Project Instructions and the HSSD, with any exceptions noted below. 1. Survey extents were modified on the north side from the extents provided in the Project Reference File (PRF) with the Project Instructions: In the set-spaced area only, H12949 was extended north into the area originally assigned under H12948 by approximately 2.7 km. This was done to optimize line planning to facilitate operations prior to commencement of survey operations. This made H12949 slightly larger in area (and H12948 slightly smaller). Regardless, the affected area received survey to identical specifications. Survey limits for both the 2 km wide corridor (requiring full coverage) and the set-spaced areas were achieved. Note the far western "corner" of the survey area, approximately 60-02-40.5 N, 165-37-09.9 W received coverage under a concurrent adjacent survey, H12868. The specified inshore limit of hydrography (farthest offshore of either the 4 m depth contour, or the line defined by the distance seaward from the MHW line, which is equivalent to 0.8 mm at the scale of the largest scale nautical chart), was not encountered in this survey area.The purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. The project (of which this survey sheet is one of eight separate, adjacent sheets) covered approximately 570 SNM of seafloor, all Priority 2 area as identified in the 2012 NOAA Hydrographic Survey Priorities document. There is an emerging need to provide modern hydrography in the Arctic to update nautical chart products. In this project area, east of Nunivak Island, deep-draft traffic is operating in relatively shoal areas that have not been surveyed in over 100 years. A 600' chemical tanker (Champion Ebony) grounded on an uncharted shoal in this survey area on June 24th, 2016, just days before survey operations were scheduled to commence. Fortunately, no discharge occurred, but the incident emphasized the need for chart updates in the area. Refer to the concurrent survey H12950 for more information on the grounding incident. Survey data from this project is intended to supersede all prior survey data in the common area and support larger scale nautical chart products.The entire survey is adequate to supersede previous data.All waters in defined survey corridorFull coverage: 100% Side Scan Sonar with concurrent Multibeam and BackscatterAll survey areas outside of defined survey corridorSet-spaced MBES: 500 m set line spacing Multibeam and BackscatterCoverage requirements were met for all areas. Lead Hydrographer's notes applicable to coverage review are as follows. Full coverage (corridor) area: Full coverage was achieved in the defined survey corridor. Coverage in the corridor area conforms with HSSD requirements described in Section 5.2.2.3, Option B: 100% SSS coverage with concurrent MBES. * In a few cases, SSS data shows small along-track gaps. These were examined and filled with MBES data to ensure full coverage, sometimes re-accepting high quality soundings that were auto-rejected during the MBES filtering process. * A large gap in SSS coverage at the south end of the corridor area caused by early termination of SSS data logging, approximately centered at 59-49-52 N, 165-27-55 W received SSS coverage primarily under the neighboring survey to the south, H12950. A small portion of a gap remained, which was successfully filled with MBES data. Set-spacing area: MBES-only data was acquired at 500 m spacing in all assigned areas outside the corridor to set-spacing standards. SSS was not collected in the set-spaced areas. Splits: Bathymetric line splits were not acquired to investigate charted depths because charted depths shoaler than survey depths did not fall between two survey lines given the scale of the affected chart. Two dedicated splits were acquired in the south portion of the corridor area to develop seafloor mounds that were visible between lines in SSS data. In other areas rejected data was re-accepted when it was of high quality to better develop shoaler areas between lines. However, in other areas, shoals, contours, and significant deeps were adequately defined by the mainscheme lines and no further splits were necessary. Survey overview showing coverage.SupportFiles\2_H12949_Coverage.jpgQualifier 1050116000970190ASV-CW5088000590130020400015703208.95000662016-07-172016-07-182016-07-192016-07-212016-07-262016-07-292016-08-05Refer to the Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessels, quality control procedures, and data processing methods. Additional information to supplement sounding and survey data and any deviations from the DAPR are discussed in the following sections.Qualifier 105321.8ASV-CW55.50.5The Qualifier 105 (Q105) is a 32 m aluminum hull vessel owned and operated by Support Vessels of Alaska. The Q105 acquired all multibeam data and provided housing and facilities for on-site data processing. The vessel also collected bottom samples, deployed BMPG tide gauges, and deployed/recovered the ASV-CW5 vessel. The ASV-CW5 (C-Worker 5) is a 5.5 m aluminum hull Autonomous Surface Vessel (ASV) owned and operated by ASV Global. The ASV was operated in an unmanned, but monitored mode, collecting SSS and MBES data in close proximity to the Q105. Refer to the DAPR for vessel photos, offset diagrams, and more information on vessel operations.Teledyne ResonSeabat 7101MBESApplanixPOSMV 320 V5Positioning and AttitudeApplanixPOSMV 320 V4Positioning and AttitudeValeportRapid SVT 200BarSound Speed ProfilerTeledyne OceanscienceRapidCASTSound Speed Profiler Deployment SystemTrimble5700Base StationSea-Bird ElectronicsSBE 26+Submerged Tide GaugeDAA (YSI - Xylem)WaterLOG H-350XLVented Tide GaugeAML OceanographicMinosX with Xchange SensorsConductivity and Temperature GaugesEdgeTech4200-MPSSSDetails on equipment specifications, configurations, quality control methodology, and methods of operation are described in the DAPR.SAR: Edgetech 4200 Side Scan Sonar was also used for data acquisition as part of H12949.Crosslines were acquired in accordance with the requirements described in Section 5.2.4.3 of the 2016 HSSD. Effort was made to ensure crosslines had good temporal and geographic distribution, were run so as to enable maximal nadir-to-nadir comparisons, and percent of mainscheme LNM requirements were achieved (4% for complete coverage areas, and 8% for set-spacing coverage areas). Since the complete coverage areas utilized SSS, and therefore, had minimal MBES swath overlap in many locations, the higher standard of 8% was assumed (and achieved) sheet-wide. Crosslines were conducted with both vessels to ensure there was ample overlap for inter-vessel comparisons, with each vessel crossing the other's mainscheme lines. Since the two vessels worked in close proximity and ran parallel lines, crosslines were usually collected in sets, with one vessel on each adjacent line. In this area, crosslines were conducted concurrently with bottom sampling, usually during the transit between sample locations. Therefore, crosslines do not always intersect mainscheme lines at right angles. However, in all cases, crosslines have ample data for nadir-to-nadir and nadir-to-outer beam comparisons. The crossline analysis was conducted using CARIS HIPS “QC Report” routine. Every crossline was selected and run through the process, which calculated the depth difference between each accepted crossline sounding and a QC BASE (CUBE-type, 1 m resolution) surface’s depth layer created from the mainscheme data. QC BASE surfaces were created with the same parameters used for 1 m surfaces as the final surfaces, with the important distinction that the QC BASE surfaces did not include crosslines so as to not bias the QC report results. Differences in depth were grouped by beam number and statistics computed, which included the percentage of soundings with differences from the BASE surface falling within IHO Order 1. When at least 95% of the sounding differences exceed IHO Order 1, the crossline was considered to “pass,” but when less than 95% of the soundings compare within IHO Order 1, the crossline was considered to “fail.” A 5% (or less) failure rate was considered acceptable since this approach compares soundings to a surface, instead of a surface to a surface. Results: Agreement between the BASE surfaces and crossline soundings is excellent. All crossline comparisons pass with 95% (or more) of soundings comparing to within IHO Order 1. Refer to Separate II: Digital Data for the detailed Crossline QC Reports.0.0380.148TCARIQualifier 10500.4010.025ASV-CW500.4010.025All soundings were assigned a horizontal and vertical value for estimated total propagated uncertainty (TPU). Refer to the DAPR for more detail concerning the parameters and methods used for computation of sounding uncertainty. Note that fixed tide error values (0.038 m measured, 0.148 m zoning) entered during TPU computation were project-wide error averages for tide zones that were ignored by CARIS during TPU computation in favor of real-time tide error estimates loaded coincident with the TCARI model. Therefore, these static error estimates for tide zoning error did not affect final TPU computations. Real-time error estimates for attitude, positioning, and tide were used over fixed error estimates defined in the HVF. Exceptions, if they exist, are listed in Section B.3 of this report. The BASE surfaces were finalized in CARIS HIPS, so that the final uncertainty value for each grid cell is the greater of either standard deviation or uncertainty. The uncertainty layer of each final surface was then examined for areas of uncertainty that exceeded IHO Order 1. Uncertainty for the surfaces ranged from 0.21 m to 0.54 m for the 2 m surface and 0.13 m to 0.59 m for the 4 m surface. The vast majority of grid cells have uncertainty values within IHO Order 1. Few exceeded IHO Order 1. Highest uncertainties were found in areas of varying bottom topography such as slopes and near bottom features and sandwaves where high standard deviations are caused by the wide depth ranges of soundings contributing to each grid cell, outer edges of multibeam swathes without adjacent line overlap, and areas exhibiting sound speed or motion artifact error. Despite elevated TPU values for these grid cells, the data is within specifications. This survey junctions with three contemporary surveys -- H12868, H12948, and H12950 -- which were conducted concurrently with this survey as part of the overall project, OPR-R300-KR-16. Difference surface methodology was used for the junction comparison. The depth layer from 2 m resolution CUBE surfaces from each survey were differenced from each other in CARIS HIPS, resulting in a difference surface. Values were extracted and statistics generated to quantify agreement. Any areas of significant disagreement, generally those exceeding IHO Order 1, were investigated to determine the cause. Survey junctions with this sheet.SupportFiles\4_H12949_Junctions.jpgH12868400002016TerraSondNWAgreement is excellent, averaging 0.028 m, with a standard deviation of 0.104 m, with differences falling in a range of -0.362 to 0.415 m. None exceed IHO Order 1.H12948400002016TerraSondNEAgreement is excellent, averaging 0.044 m, with a standard deviation of 0.091 m, with differences falling in a range of -0.351 to 0.351 m. None exceed IHO Order 1.H12950400002016TerraSondSAgreement is excellent, averaging 0.004 m, with a standard deviation of 0.165 m, with differences falling in a range of -0.678 to 0.488 m. Few exceed IHO Order 1. The few exceeding IHO Order 1 were investigated and the cause determined to be a tidal bust. Only isolated or small groupings of grid cells in the difference surface failed to meet specifications, rather than the entire line.Echosounder confidence checks consisting of bar checks, lead lines, and inter-vessel acoustic comparisons were undertaken on this project. Results were good, with agreement averaging 0.009 m for bar checks, 0.190 m for lead lines, and 0.059 m for inter-vessel acoustic comparisons . Refer to the bar check, lead line, and echosounder depth comparison logs available in Separate I: Acquisition and Processing Logs for specific results. Refer to the project DAPR for more information regarding QC checks methodology.7101 Beam PatternA distinct beam pattern was obvious in the data set in certain areas, with a fuzziness or “horn” like features on both sides of nadir on multibeam swaths, coinciding with the bottom detection shift from phase to amplitude detection. The pattern is common with Reson 8101/7101 multibeam echosounders in certain bottom types. Power and range settings were adjusted in acquisition to minimize the issue, with little effect. However, the “horns,” which can be as great as 0.20 m in height, appear to be largely ignored by the CUBE algorithm during surface creation, with minimal effect on the final surfaces.7101 Errant PingsErrant or bad pings is evident periodically in the multibeam swath data. This occurred regularly on both 7101 systems. The issue manifests itself as a single ping, or swath, that is skewed (or rolled) from the seafloor at an angle. The cause is unknown, but does not correlate to any spikes in attitude data. These were normally removed manually during swath edit review, resulting in small along-track gaps as viewed in swath editor plan view. However, since only single pings were affected and ping rates were high (generally 10 or more per second), there is no significant detrimental effect on data density. Unrejected errant pings in the dataset may remain, but do not have significant detrimental effect on final surface quality. Sound Speed ErrorA general downward or upward across-track cupping in multibeam data, indicative of sound speed error, is present sporadically in the data set. The sound speed error adversely affected outer beams by up to 0.20 m in places. To minimize the error, sound speed profiles were collected every 2 hours during multibeam operations, and filters were used in processing to remove the outermost beams. The effect of sound speed error on final surfaces is relatively minor, normally not exceeding 0.10 m, and is within specifications.Motion ArtifactMotion artifact is occasionally visible in the final multibeam surfaces. This is the result of uncompensated effects of motion, particularly due to roll. The primary contributer was motion induced on the survey vessels by poor sea states (often 1.5 m or greater), a common and unavoidable condition in this highly exposed area. A survey-grade Applanix POSMV 320 was used for motion compensation, but residual error within the manufacturer specifications for the system remains nonetheless. The problem was addressed in processing by identifying lines with the greatest error and iteratively applying more aggressive outer beam filters, in some instances rejecting beams greater than 55 degrees either side of nadir. No adjustments to line spacing were made in acquisition to compensate for the rejected outer beam data because complete MBES coverage was not required. Following the additional filtering, the effect on the final surface is normally 0.25 m or less, which is within specifications. Note that the ASV-CW5, at 3.5 m in length was a much smaller survey platform than the Q105 at 32 m in length, and therefore, experienced greater induced motion at the same sea states, resulting in more motion artifact for lines run simultaneously.Tide ErrorPeriodic vertical offsets or “busts,” indicative of tide error, is present sporadically in the data set. The majority of lines show good matchup with crosslines or adjacent lines, but busts of up to 0.4 m are occasionally present and attributable primarily to tide error.Example tide error. Crossline 0546-Q105-218-F34XL2 (cyan) is offset vertically from intersecting mainscheme lines by up to 0.40 m. Final 2 m surface is shown as light blue.SupportFiles\5_TideBustExample.jpg2 hoursSound speed profiles, or casts, were acquired aboard the Q105 while underway with an Oceanscience RapidCAST system, which utilized a Valeport sound speed profiler. The interval between subsequent casts was normally 2 hours. The sound speed sensor was lowered as close as possible to the seafloor, and then retracted to the vessel and downloaded. When surveying lines covering widely varying water depths, casts were favored in the deeper portions to ensure the entire water column was captured. The ASV-CW5 vessel was not equipped to collect sound speed profiles. Instead, the profile data collected aboard the Q105 was used to correct all ASV-CW5 data. This was possible because the ASV-CW5 worked simultaneously and in close proximity (usually within 200 - 800 m) of the Q105 at all times. Up and down portions of the profiles were averaged and a combined profile at a standardized 0.10 m depth increment was output to CARIS SVP format with time and position. Sound speed profiles were applied with the “nearest in distance within time” method in CARIS HIPS, with time set to 2 hours. Exceptions, if they occurred, are listed in section B.3 of this report. Refer to the DAPR, section B.2.4 "Data Coverage and Density," for details on the equipment, software, and methodology used to meet object detection, coverage, and data density requirements. Corrections applied to echo soundings are detailed in the project DAPR. No deviations occurred, except as described below. Note that despite exceptions, affected data is within specifications. Sound speed exception: The following lines required correction for sound speed that was different than the project standard of nearest in distance within 2 hours. Nearest in distance within 3 hours 0383-Q105-203-F4FS06_-_0002 SMRMSG real-time error exception: SMRMSG files could not be loaded to the following lines. Therefore, real-time error estimates were not available for post-processed attitude data during TPU computation. Static error estimates from the HVF were used instead. 0316-ASV-208-F4FS04_-_0001 0316-ASV-208-F4FS04_-_0002 0317-ASV-208-F3FS17_-_0001 0317-ASV-208-F3FS17_-_0002 Calibrations were undertaken as described in the DAPR. No deviations occurred.Multibeam backscatter was logged at all times during this survey, but not processed. Raw DB and XTF files, submitted with the survey deliverables, contain the backscatter records.V5.4 There were no software configuration changes after the DAPR was submitted.H12949_MB_4m_MLLW_FinalCUBE4080NOAA_4mSet-spaced MBESH12949_MB_2m_MLLW_FinalCUBE21840NOAA_2mComplete MBESH12949_SSS_1m_100-F1SSS Mosaic1040N/A100% SSS, block F1H12949_SSS_1m_100-F2SSS Mosaic1040N/A100% SSS, block F2The final depth information for this survey was submitted as two CARIS BASE surfaces (CSAR format) and two georeferenced SSS mosaic images which best represented the seafloor at the time of the 2016 survey. The surfaces and images were created from fully processed data with all final corrections applied. MBES Data: The MBES surfaces were created using NOAA CUBE parameters and resolutions in conformance with the 2016 HSSD. Corridor (full coverage) area surfaces were generated in accordance with section 5.2.2.3 (Complete Coverage) while the set-spacing area surface was generated in accordance with section 5.2.2.4 (Set Line Spacing). Surfaces were finalized, and designated soundings were applied where applicable. Horizontal projection was selected as UTM Zone 3 North, WGS84. Non-finalized versions of the CSAR surfaces are also included. These do not have the _Final designation in the filename. File names for final surfaces was done in accordance with section 8.3.2 (Bathymetric Data) of the 2016 HSSD for MBES data. SSS Data: SSS mosaics were exported from SonarWiz as georeferenced TIFF images at 1 m resolution. These are projected as WGS84 UTM Zone 3N. A world file (.TFW) accompanies each TIFF image to provide the georeferencing. SSS filenames are as specified in section 8.2.1, with the addition of an area or block designation at the end of filenames. Singular SSS images for this survey was not practical due to extremely large GeoTIFF file sizes that would result from combined images. Therefore, images were created by survey block, and the block name added as a suffix to the filenames. For this survey, block "F1" denoted the north half of the corridor area, while "F2" the south half of the corridor area. Supplementary Data: A CARIS HOB file was submitted (H12949_FFF.HOB) with the survey deliverables as well. The final feature file (FFF) contains meta-data and other data not readily represented by the final surfaces, including DTONs that were submitted previously during the course of the survey, if applicable, and bottom samples. A CARIS HOB file containing SSS contacts was NOT submitted because no significant contacts (not already adequately captured in the MBES surfaces) were found. Many small contacts were observed in deeper portions of this survey area, but did not meet criteria for significance. Significant contacts were those identified in the SSS record as having height above the seafloor of 1 m, or greater, in depths less than 20 m, and heights of 10%, or greater, of water depth in depths 20 m and deeper. The 10% allowance is an exception granted for this project by NOAA (see correspondence) to the 5% requirement described in the 2016 HSSD. In this area, contacts were more common in deep water than in shallow water, and this exception was made to limit the number of contacts requiring multibeam development in deeper water, and therefore, facilitate the survey of additional areas over performing multibeam developments. This was considered acceptable given that vessels of 20 m draft are extremely unlikely to attempt transiting this area given its shoal approaches. Each object is encoded with mandatory S-57 attributes, additional attributes, and NOAA Extended Attributes (V#5.4).Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Mean Lower Low WaterNelson Island9466298Eastern Nunivak Island9466012Kipnuk9465953Offshore South Nunivak9465683TCARIr300kr2016_rev.tcFinal2016-11-172017-01-26In addition to the subordinate tide station installed to support the project, submerged BMPG (bottom mounted pressure gauges) were also deployed throughout the survey area to capture zoning characteristics. These zoning gauges were used for QC purposes only. All data has been submitted to CO-OPS. A final TCARI grid covering the survey area was issued on January 13th, 2017. However, the grid file was revised and reissued (filename "r300kr2016_rev.tc") on January 26th, 2017. This revised grid "r300kr2016_rev.tc" demonstrated better results in general, and was applied to all data.WGS84UTM Zone 3NSingle Base0056Toksook BayThe project base continuously logged GPS data at 1 Hz and was utilized to post-process position data in Applanix POSPac MMS software. The Continually Operating Reference Station (CORS) site at Mekoryuk, station ID "AB08," was used for preliminary post-processing in the field, quality control checks for the project base station, and for final positions in rare instances where the project base station experienced outages. All real-time positions for both vessels were replaced in processing with post-processed kinematic (PPK) solutions, with few exceptions (noted if applicable earlier in this report). Quality control confidence checks were performed at least weekly on the survey vessels as well as the base station position. RMS error estimates for positioning results were very good, with RMS error estimated at 0.10 m (or better). Refer to the project DAPR for additional details on quality control checks and results. WAAS was used for real-time corrections in the field, but was replaced in post-processing with the PPK solution, as described in the DAPR. Note: Final positions are WGS84 (instead of NAD83) per Section 2.1 of the 2016 HSSD, which was the governing guidance during the time of field operations.The chart comparison was performed by examining all Raster Navigational Charts (RNCs) and Electronic Navigational Charts (ENCs) that intersect the survey area. The latest editions available at the time of the review (February 10th, 2017) were used. The chart comparison was accomplished by overlaying the finalized BASE surfaces with shoal-biased soundings, and a final feature file on the charts in CARIS HIPS. The general agreement between charted soundings and survey soundings was then examined and a more detailed comparison was undertaken for any shoals, or other dangerous features. In areas where a large scale chart overlapped with a small scale chart, only the larger scale chart was examined. Results are shown in the following sections. It is recommended that in all cases of disagreement this survey supersedes charted data. USCG Notice to Mariners (NM) and USCG Local Notice to Mariners (LNM) were checked for updates affecting the area. None were found that were issued subsequent to issuance date of the project instructions, nor prior to the completion of operations that affect the survey area.1600624111534076372015-122017-01-172017-01-21This survey fully intersects only a small number of charted soundings. Overall sounding agreement is good, within 1 fathom, with exceptions noted below: 1. Depth in the vicinity of charted 8 fathom sounding at 59-58-53 N, 165-29-53 W was found to be approximately 10.5 to 11 fathoms. However, the charted sounding is on the edge of survey coverage. Therefore, it is recommended the 8 fathom sounding remain as charted. Agreement was also examined for significant trends. None was noted except as follows: 1. The 10 fathom contour is charted significantly further east (up to 6.8 km) than its actual location. See included figure that shows soundings from this survey overlaid on chart 16006. Soundings from this survey overlaid on chart 16006. Survey soundings (orange) are shown in fathoms and feet. Charted soundings (black) are shown in fathoms and fractional fathoms.SupportFiles\6_H12949_ChartCompare.jpgUS2AK95M153407642016-08-292016-08-29falseThe same differences observed for the RNC apply to the ENC.No maritime boundary points were assigned for this survey.There are no charted features labeled PA, ED, PD, or Rep. within the survey extents.No uncharted features were found during this survey.No DTONs were found during this survey.No shoals or hazardous features exist in the survey area.No channels exist in the survey area.Bottom samples were collected for this survey. 8 sample locations were assigned in the Project Reference File (PRF) supplied with the Work Instructions. Samples were obtained at 5 of the 8 assigned locations. At 3 locations samples could not be obtained despite a minimum of 3 attempts at the location, with each attempt returning a closed sampler indicating seafloor contact, but no sample. Unsuccessful samples were at the following locations: 60-01-59.035 N, 165-33-37.396 W 60-00-10.260 N, 165-27-51.488 W 59-52-41.806 N, 165-29-51.081 W Successful samples returned a variety of seabed types, ranging from fine sand to pebbles, shells, and cobbles. Samples were not retained. However, photos were taken of most samples prior to discarding. Bottom characteristics were encoded as SBDARE objects in the FFF, with any applicable photos in the accompanying "multimedia" directory, with the survey deliverables. Unsuccessful samples are encoded as SBDARE objects with NATSUR = "Unknown" per the HSSD.This survey did not intersect shoreline, and shoreline investigation was not assigned.Comparison with prior surveys was not required. However, Junction analysis, described previously in this report, was undertaken for overlapping contemporary surveys.No ATONs were observed in the survey area, and none were assigned for investigation.No overhead features existed within the survey area.There are no submarine features of special note.Ferry routes and terminals do not exist within the survey area.Platforms do not exist within the survey area.Any significant features and conditions encountered have been described previously.No construction or dredging was occurring within the survey extents, nor are there any known future plans for construction or dredging in the survey area.No new surveys are recommended in this area.No new chart insets are recommended in this area.Field operations contributing to the completion of survey H12949 were conducted under my direct supervision with frequent personal checks of progress, integrity, and adequacy.This report, digital data, and all other accompanying records are approved. All records are respectfully submitted and forwarded for final review.The survey data was collected in accordance with the project Work Instructions and Statement of Work, and meets or exceeds the requirements set in the 2016 NOS Hydrographic Surveys and Specifications Deliverables (HSSD) document. This data is adequate to supersede charted data in common areas. This survey is complete and no additional work is required with the exception of any deficiencies, if any, noted in this Descriptive Report. The Data Acquisition and Processing Report (DAPR) and Horizontal and Vertical Control Report (HVCR) were submitted concurrently with this report and the survey deliverables. Other significant required reports or data packages submitted separately but not already described are listed below.Andrew Orthmann, C.H.TerraSond Charting Program Manager2017-03-05Coast Pilot Review (OPR-R300-KR-16_Coast Pilot Review Report)2017-02-13NCEI Sound Speed Data2016-12-20Trained Marine Mammal Observers Logsheet2016-11-21Marine Mammal Observation Logs2016-11-17Tides and Water Levels Package and Reports (one for each project tide station)2016-10-21