OPR-R340-KR-21 Approaches to Egegik Bay, AK Bristol Bay Terrasond H13442 5 na 17NM WNW of Egegik Extension Alaska United States 40000 2021 Andrew Orthmann Navigable Area 2021-08-16 2021-08-20 2021-09-18 Multibeam Echo Sounder Multibeam Echo Sounder Backscatter meters UTC Pacific Hydrographic Branch Any revisions to the Descriptive Report (DR) applied during office processing are shown in red italic text. The DR is maintained as a field unit product, therefore all information and recommendations within this report are considered preliminary unless otherwise noted. The final disposition of survey data is represented in the NOAA nautical chart products. All pertinent records for this survey are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via https://www.ncei.noaa.gov/. CC0-1.0 (NOAA Contractors) CC0-1.0 https://creativecommons.org/publicdomain/zero/1.0/ https://creativecommons.org/publicdomain/zero/1.0/legalcode These data were produced under contract with NOAA and any potential copyright was assigned to NOAA. NOAA waives any potential copyright and related rights in these data worldwide through the Creative Commons Zero 1.0 Universal Public Domain Dedication (CC0). Contractor The survey area is located in Bristol Bay, Alaska. A number of rivers flow into the bay and host the world's largest salmon runs. Seasonal fishing activity, including in the nearby Egegik fishing district, is the major driver of the economic activity in the area. The region is relatively remote. None of the area communities are accessible by road. Travel and resupply is done by air or water. The closest communities to the survey area are Pilot Point (pop. 101, 2019) and Egegik (pop. 58, 2019). Dillingham (pop. 2,215, 2019), about 70 NM to the north, is the hub of the region with direct daily flights to and from Anchorage. Vessel traffic consists mostly of barges that service the local communities and fishing vessel activities, especially during the busy summer fishing season. Fishing activity usually begins in June, peaks in July, and is largely over by August. The Egegik fishing district can have as many as 800 fishing boats laying nets and working in close proximity to each other at the height of the season. This project was timed to take place late in the summer season when fishing activities had diminished. Tides have a large range here, usually four to five meters between high and low each day. As a result tidal currents are also strong, frequently in the range of 2-3 knots. The area is relatively shallow (approximately 31.7 m at the offshore extent) with a gradual slope towards shore. The seafloor is primarily composed of shifting sand, evidenced by bottom sample results and many sandwave features spread throughout the survey area. Bathymetric data collection was carried out in August and September of 2021 under project OPR-R340-KR-21, with final processing and reporting carried out from October through December, 2021. Work was completed concurrently with five other nearby sheets, and done in accordance with the Hydrographic Survey Project Instructions (original dated 2/22/21, updated 8/16/21), Statement of Work (2/24/21), and the Hydrographic Surveys Specifications and Deliverables (HSSD, May 2020 edition). 58.01697222222222 158.06951666666666 57.79639722222222 157.62170277777778 Image showing overview of survey extents. file:///M:/OPRR340KR21/Surveys/H13442/01_HDR/Working/Report/Original/H13442_DR/SupportFiles/H13442_Survey_Extent.jpg Survey limits were acquired in accordance with the requirements in the Project Instructions and the HSSD. The purpose of this survey is described as follows in the Project Instructions document: The Approaches to Egegik Bay project located in Bristol Bay, Southwest Alaska, will provide contemporary surveys to update National Ocean Service (NOS) nautical charting products and services. The survey will provide modern bathymetry to update historic charted data, survey uncharted waters, and address concerns of navigational risk due to shoal formation. Direct user feedback from the Western Alaska Tanker Lightering Best Practices Committee via the Alaska Maritime Prevention & Response Network, identified areas that support Ship-to- Ship transfers of oil products, commonly referred to as “lightering.” Together with the Automatic Identification Systems (AIS) traffic patterns feeding the Hydrographic Health model, the lightering areas helped to define the 749 square nautical mile survey extents. Areas to be surveyed include uncharted waters and historic data from 1914 to the 1940s. This work will directly support the maritime services available to the remote native coastal community of Egegik (Igyagiiq) located within the mouth of the Egegik River. Additionally, this project will provide support for other NOAA Hydrographic surveys and regional tidal products by installing two temporary water level measuring stations in the vicinities of Egegik and Pilot Point. Modern charting products reduce the risk to navigation, increasing maritime safety and supporting the regions maritime infrastructure and commerce. Remote harbors and lightering sites are are essential to the maritime infrastructure of Alaska's communities. This project will provide that critical data for the updating of National Ocean Service (NOS) nautical charting products. The entire survey is adequate to supersede previous data. All waters in survey area in Sheets 4, 5, and 6 Set Line Spacing MBES with concurrent backscatter at 400 m perpendicular to contours (Refer to HSSD Section 5.2.2.4, Option A) Coverage requirements were met. The following notes provide additional clarification. The project required 5,726 LNM of survey data to be acquired project-wide. This consisted of the originally assigned 5,429 and an additional 297 authorized by the Government on 9/8/21 (see correspondence included with project deliverables). 6,007 LNM were acquired project-wide, exceeding the requirement by 281 LNM. The excess of 4.9% was collected to compensate for inefficiencies incidental to data collection such as crossline mileage that exceeded requirements, data acquired on run-ins or run-outs including on turns in shallow water in order to scout depths between lines, and excess overlap (if any). LNM quantities do not include transit or calibration data, or mileage that does not meet HSSD specifications. The inshore limit for this survey was the NALL, which was normally 3.5 m water depth. 3.5 m depth (or shoaler) was reached along the entire inshore limit. An exception is in the NE corner of the survey area, where the northern-most survey line ends before reaching 3.5 m water depth. This was done because the same line was ran under junctioning sheet H13441, wherein it does extend in to 3.5 m water depth. Image showing overview of survey coverage. file:///M:/OPRR340KR21/Surveys/H13442/01_HDR/Working/Report/Original/H13442_DR/SupportFiles/H13442_Survey_Coverage.jpg Qualifier 105 0.0 771.9 0.0 0.0 0.0 0.0 0.0 114.0 0.0 Sealegs 0.0 39.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 811.4 0.0 0.0 0.0 0.0 0.0 114.0 0.0 14.0 11 0 0 0 171.6 2021-08-20 2021-08-21 2021-08-22 2021-08-23 2021-08-24 2021-08-25 2021-08-26 2021-08-27 2021-08-28 2021-09-01 2021-09-04 2021-09-08 2021-09-13 2021-09-15 2021-09-16 2021-09-17 2021-09-18 Refer 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 105 32.0 1.8 Sealegs 5.5 0.5 RV Qualifier 105 (Q105) file:///M:/OPRR340KR21/Surveys/H13442/01_HDR/Working/Report/Original/H13442_DR/SupportFiles/Q105.jpg Sealegs skiff file:///M:/OPRR340KR21/Surveys/H13442/01_HDR/Working/Report/Original/H13442_DR/SupportFiles/Sealegs.jpg The Qualifier 105 (Q105) is a 105' aluminum-hull vessel owned and operated by Support Vessels of Alaska (SVA). The Q105 acquired multibeam data and provided housing and facilities for on-site data processing. The vessel was also used to collect bottom samples, deploy/recover tide buoys, conduct sound speed casts, conduct feature investigations, and deploy/support the Sealegs vessel. The Sealegs is a 5.5 m RHIB-style skiff owned and operated by SVA. It was deployed via deck crane from the Q105 when conditions were favorable, and used to collect multibeam data in the shoalest portions of the survey area that were not readily accessible by the larger vessel. MBES Teledyne RESON SeaBat T50-R MBES Teledyne RESON SeaBat T20-P Positioning and Attitude System Applanix POS MV 320 v5 Sound Speed System Teledyne Oceanscience rapidCAST Sound Speed System Valeport SWiFT SVP Sound Speed System AML Oceanographic MicroX SV Sound Speed System AML Oceanographic SV-Xchange The survey vessels were configured for MBES data collection with similar survey equipment and software. Both vessels utilized Reson Seabat MBES systems (T-50 on the Q105, T-20 on the Sealegs), with surface sound speed measurements provided by AML Oceanographic Micro-X sensors. Both vessels used Applanix POSMVs (Wavemaster II) with submersible IP-68 rated IMUs for attitude and position measurements. Sound speed profiles were collected using a Valeport SWiFT sensor (deployed while underway using a Teledyne Oceanscience RapidCast system) on the Q105, while the Sealegs utilized a AML Oceanographic Minos-X (with P- and SV-Xchange sensors) deployed by hand. QPS QINSy software, running on Microsoft Windows 10-based PCs, was used for multibeam data logging and vessel navigation. Crossline LNM totaled 14.0% of mainscheme. Effort was made to ensure crosslines (XLs) had good temporal and geographic distribution, were angled to enable nadir-to-nadir comparisons, and that the required minimum percent of mainscheme LNM was achieved. Crosslines were often collected while transiting across the survey area to reach a different survey priority such as bottom sample locations or infills, often leading to crosslines that were diagonal to the direction of mainscheme lines. This also resulted in total XL LNM that exceeded the minimum requirements (8% of mainscheme) since it was preferable to collect more data for QC purposes when crossing mainscheme instead of transiting without logging. The crossline analysis was conducted using CARIS HIPS “Line QC Report” process. Each crossline (with all associated file segments) was selected and run separately through the process, which calculated the depth difference between each accepted crossline sounding and a "QC" BASE (CUBE-type) surface’s depth layer created from the mainscheme data. The QC surface was created with the same parameters and resolution used for the final surface, with the important distinction that the QC surface did not include crosslines so as to not bias the results. Differences in depth were grouped by beam number and statistics were computed, including the percentage of soundings with differences from the QC surface falling within IHO Order 1a. When at least 95% of the sounding differences exceed IHO Order 1a, 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), allowing for the possibility that noisy crossline soundings that don't adversely affect the final surface could be counted as a QC failure in this process. Lines selected as crosslines and their percentage (%) of soundings passing IHO Order 1a, sorted from highest passing to lowest, are listed below. 1410-Q105-244-E1_XL2 -- 100.0% pass 1416-Q105-244-E1_XL4 -- 100.0% pass 1417-Q105-244-E1_XL5 -- 100.0% pass 1939-Q105-258-E01XL -- 100.0% pass 1941-Q105-258-E02XL -- 100.0% pass 1943-Q105-259-E03XL -- 100.0% pass 1944-Q105-259-E04XL -- 100.0% pass 1980-Q105-259-E_XL -- 100.0% pass 1414-Q105-244-E1_XL3 -- 99.9% pass 2073-Q105-261-E_XL12 -- 99.9% pass 1916-Q105-256-E1XL00005 -- 99.5% pass 2069-Q105-260-E_XL10 -- 99.5% pass 1412-Q105-244-E1_XL3 -- 99.3% pass 1945-Q105-259-E05XL -- 99.3% pass 1011-Q105-239-E1XL00001 -- 98.8% pass 1413-Q105-244-E1_XL3 -- 98.4% pass 1415-Q105-244-E1_XL3 -- 97.7% pass 1411-Q105-244-E1_XL2 -- 97.1% pass Results: Agreement between them mainscheme surface and crossline soundings is excellent. At least 95% of crossline soundings compare to the mainscheme surface within IHO Order 1a for all crosslines. Refer to Separate II: Digital Data for the detailed Crossline QC reports. ERS via ERTDM 0.15 0.0 Qualifier 105 0 1.0 0 0.025 Sealegs 0 1.0 0 0.025 The uncertainty layer of the final surface(s) was examined in CARIS HIPS, and also analyzed in Pydro QC Tools V3.5.14 Grid QA v6. Uncertainty of the final grid cells range from 0.279 to 0.701 m. Greater than 99.5% of grid cells have TVU falling within the allowable range by depth. The larger values were observed to be in areas of variable seafloor, usually around sandwave features, where many soundings of different depths contribute to the value of the relatively large ( 4 m ) grid cell, resulting in a higher standard deviation for the grid cell. All final grid cells are within specifications. During field operations, effort was made to ensure sufficient overlap was achieved between lines run in adjacent survey sheets in order to complete junction analysis. The "Gridded Surface Comparison V19.4" utility within Pydro was used to compare survey junctions. The utility differences the surfaces from the two surveys and generates statistics that include the percentage of grid cells that compare to within allowable TVU for the depth. 4 m resolution CUBE surfaces were used for all comparisons. Image showing an overview of junctions with this survey. SupportFiles\H13442_Survey_Junctions.jpg H13443 40000 2021 TerraSond S Lines on this survey were collected at an oblique angle to the lines collected on H13443. Survey lines from H13443 were extended to achieve at least one swath width of overlap with the southern-most lines on this survey, resulting in good overlap along their common boundary. Agreement between the two surveys is excellent. The mean difference is 0.01 m with a standard deviation of 0.07 m. 100% of grid cells agree within the allowable TVU for their depth. H13441 40000 2021 TerraSond N Lines on this survey were collected parallel to the lines collected on H13441. To ensure at least one swath width of overlap, an overlapping line was collected in both sheets along their common border. In addition, crosslines were extended where practical from each sheet into the other sheet to obtain additional overlap. Agreement between the two survey is excellent. The mean difference is 0.02 m with a standard deviation of 0.10 m. 100% of grid cells agree within the allowable TVU for their depth. Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR. Data Blowouts During rough weather conditions, especially with following seas, air bubbles would occasionally be forced under the multibeam sonar head and result in temporary loss of bottom tracking or "blowouts", sometimes causing small along-track gaps. These were examined and only reran when the gap at nadir exceeded three nodes alongtrack (generally 12 m) for mainscheme lines. In rare instances, crosslines may have alongtrack gaps that exceed 12 m due to blowouts -- these were normally not reran since crosslines were collected for QC purposes only, and more than the minimum required were acquired. Final data is within specifications. Image of the final surface showing the effect of data blowouts on a line from rough weather. file:///M:/OPRR340KR21/Surveys/H13442/01_HDR/Working/Report/Original/H13442_DR/SupportFiles/Blowout_Example.jpg Bottom Change Bottom change was observed over the course of the survey, especially between lines that were run days to weeks apart. There is evidence of sediment transport throughout the survey area, with sandwaves prevalent almost everywhere. When bottom change was observed between lines, no attempts were made to edit or otherwise "choose" a seafloor. An example of bottom change is shown below. Example of about 0.30 m of bottom change on lines run up to 24 days apart, shown in CARIS subset mode. The dark green line is a mainscheme line run on JD235, while the red and green lines are crosslines run on JD256 and JD259, respectively (57-55-13.8 N, 157-59-36.3 W) file:///M:/OPRR340KR21/Surveys/H13442/01_HDR/Working/Report/Original/H13442_DR/SupportFiles/Bottom_Change_Example.jpg Sound Speed Error Most sound speed profiles exhibited a well mixed water column due to the strong currents of the area, and as a result sound speed error in the dataset is relatively small. This error, which is characterized by a general upward or downward across-track cupping of sounding data that increases in magnitude towards the outer beams, is evident in some areas, but where it was observed the effect on final surfaces is less than 0.20 m. 2 hours Sound speed profiles or "casts" were acquired aboard the Q105 while underway with a Teledyne Oceanscience RapidCAST system, which utilized a Valeport SWiFT sound speed profiler. The Sealegs used a manually-deployed AML Oceanographic Minos-X (with P- and SV- Xchange sensors). Surface sound speed at the sonar head was monitored continuously and a new cast was collected when the surface speed varied from the previous profile's speed at the same depth by greater than 2 m/s, leading to a cast interval of approximately 2 hours. Casts were taken as deep as possible. On survey lines with significant differences in depth, the deeper portion of the line was normally favored to ensure that changes across the full water column were measured. The cast data was used to correct the sounding data using the "nearest in distance within time" (set to 3 hours) within CARIS HIPS. All equipment and survey methods were used as detailed in the DAPR. GPS Vertical Busts Although vertical agreement between overlapping lines is generally very good, normally within 0.10 m or better, vertical busts attributable to GPS positioning error are apparent sporadically in the data set. On rare occasions these reach approximately 0.20 m in this area. Any that approached or exceeded IHO Order 1a for their depth were investigated and addressed in processing. All crosslines pass within IHO Order 1a, and final surfaces are within allowable TVU for the depth. Sound Speed Exception: The last part of line 0980-Q105-236-E1EW11600 (segments 0004 and 0005) was corrected with nearest in distance within 4 hours instead of the standard 3 hours. Then, segment 0006 and 0007 were corrected with nearest in distance within 5 hours. This was necessary because the profile collection interval deviated from the normal ~ 2 hours due to adverse weather which made it temporarily unsafe to collect profiles. There is no significant adverse affect on the lines and the data is within specifications. Post-Processing Exception: The following lines used Applanix Smart Base (ASB) instead of PP-RTX processing method for post-processed positions. This was done to investigate and address vertical GPS busts that were close to, or exceeding, specifications as evidenced by agreement at line crossings. After application of ASB these lines they were brought within specifications. 0960-Q105-235-E1EW10800_-_0005 0979-Q105-236-E1EW11200_-_0001 0980-Q105-236-E1EW11600_-_0006 0982-Q105-237-E1EW12400_-_0005 0983-Q105-237-E1EW12800_-_0002 0984-Q105-237-E1EW13200_-_0005 0985-Q105-237-E1EW13600_-_0001 0986-Q105-237-E1EW14000_-_0005 0988-Q105-238-E1EW14800_-_0005 0996-Q105-238-E1EW18000_-_0006 1012-Q105-240-E1EW01600_-_0005 1948-Q105-259-EINFL00002_-_0001 0980-Q105-236-E1EW11600_-_0004 1980-Q105-259-E_XL 1011-Q105-239-E1XL00001 1414-Q105-244-E1_XL3 1415-Q105-244-E1_XL3 0867-Q105-232-E1EW03200 0865-Q105-232-E1EW02400 1013-Q105-240-E1EW02000 2069-Q105-260-E_XL10 1005-Q105-239-E1EW21600 2073-Q105-261-E_XL12 1944-Q105-259-E04XL All sounding systems were calibrated as detailed in the DAPR. Backscatter data was acquired but not processed for this survey. All equipment and survey methods were used as detailed in the DAPR. NOAA Extended Attribute Files V2021 H13442_MB_4m_MLLW_Final CARIS Raster Surface (CUBE) 4 0.0 80.0 NOAA_4m MBES Set Line Spacing The final depth information for this survey was submitted as a CARIS BASE surface (CSAR format) which best represented the seafloor at the time of the 2021 survey. The surface was created from fully processed data with all final corrections applied. The surface was created using NOAA CUBE parameters and resolutions by depth range in conformance with the 2020 HSSD. The surface was finalized, and designated soundings were applied where applicable. Horizontal projection was selected as UTM Zone 4 North, NAD83(2011). A non-finalized versions of the CSAR surface is also included which does not have a depth cutoff applied. This does not have the "_Final" designation in the filename. An S-57 (.000) Final Feature File (FFF) was submitted with the survey deliverables as well. The FFF contains data not readily represented by the final surface, including bottom samples and shoreline verification results (if any). Each object is encoded with mandatory S-57 attributes and NOAA Extended Attributes (V2021). Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR. Mean Lower Low Water Port Moller 9463502 Egegik 9464874 Dago Creek Mouth 9464512 Offshore Egegik GNSS Tide Buoy 9999778 ERS via ERTDM OPR-R340-KR-21_Egegik_ERTDM21_NAD83-MLLW_.csar All soundings were reduced to MLLW using the ERTDM NAD83 to MLLW separation model grid file provided by NOAA using ERS methodology. Two tide stations, at Egegik and Dago Creek Mouth (Pilot Point) were installed as part of the overall project but were not used for reduction of soundings. A GNSS Buoy was also deployed as an ERTDM validation site. All gauge data and validation results have been separately provided to NOAA CO-OPS. Reports (with accompanying data packages) that have been submitted directly to CO-OPS are itemized in Section E of this report. Note: During analysis of the GNSS Buoy data, which was installed as a check on the ERTDM model in an offshore portion of the project area, a discrepancy was observed. The NAD83 to MLLW separation was computed to be 11.790 m from the buoy data, while the ERTDM model had a separation value of 12.472 m at the buoy location, a difference of 0.682 m. Conversely, the NAD83 to MLLW separation values computed at the two project tide stations (Egegik and Dago Creek Mouth) agreed with the ERTDM model to 0.111 m and 0.079 m, respectively, which is within the uncertainty stated for the ERTDM model in the Work Instructions (0.15 m). This suggests the possibility of error in the tide model that exceeds specifications offshore. The discrepancy was brought to the COR's attention (see tides correspondence) but was unresolved at the time of this submittal. The result of higher than actual separation values applied to the GNSS altitude data would be a deep bias to final soundings; therefore further investigation is recommended. Products created during office processing were generated in NAD83 UTM 4N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit. H13442 was conducted in 2021. At the time, the field was provided a preliminary ERTDM SEP Model for the field party to reduce their sounding elevations from ellipsoidal heights to depths referenced to MLLW. As part of their survey operations, the field party set up a series of tide buoys to help improve ellipsoidal-to MLLW datum reduction modeling in the area. In early 2023, HSTB provided updated SEP models to the hydrographic branches, based on the tide data collected by the buoys. The hydrographic branch used two vertical shifts to transform submitted data depths. The first shift used the original 2021 SEP Model to return gridded depths to the ellipsoidally referenced elevations. The second shift used the improved 2023 SEP to reduce grid depths back to MLLW. The hydrographic branch did not re-process the individual soundings that generate the grids. All HDCS data remains referenced to MLLW, based on the original SEP model. Sounding depths of original HDCS sounding data vary from the grids approved for charting anywhere between +/- 0.25m. North American Datum 1983 Projected UTM 4 Smart Base RTX Post-processing of all navigation data for final positions was done in Applanix POSPac MMS (v8.5 or v8.7) software. Trimble PP-RTX was normally used as the processing methodology within POSPac. However, in the process of troubleshooting occasional vertical GPS busts, the Applanix Smart Base (ASB) method was used in POSPac and applied to lines, which in most cases improved agreement. Lines that utilized ASB for their final positions were itemized earlier in this report. Real-time positions were primarily RTK. Hemisphere SmartLink antennas on each vessel were set to receive the subscription-based Atlas H-10 service, which output RTCM corrections to each vessel's POSMV, allowing them to operate in RTK mode. This assisted with real-time positioning, especially helping to ensure depth requirements were met. However, all real-time positions were replaced in post-processing with PPK corrections, as described previously. The Wide Area Augmentation System (WAAS) was used incidentally for real-time positions when there were issues receiving RTK corrections. However, all real-time positions were replaced in post-processing with PPK corrections, as described previously. The chart comparison was performed by examining the best-scale Electronic Navigational Charts (ENCs) that intersect the survey area. The latest edition(s) available at the time of report compilation were used. The chart comparison was accomplished by overlaying the final surface(s) with shoal-biased soundings and the final feature file (FFF) 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. When comparing to survey data, chart scale was taken into account so that 1 mm at chart scale was considered to be the valid radius for charted soundings and features. ENC metadata and non-specific geographic area objects on the ENC(s) that overlap the survey area were not investigated. Results are shown in the following sections. It is recommended that in all cases of disagreement this survey should supersede charted data. There are few charted soundings overlapping the project area. For the soundings that do exist, agreement is generally poor. Although a few soundings agree to within 1 m, most have greater disagreement, to as much as 10 m of difference for a charted 31 m sounding where this survey found depths of 20 m nearby. Although there are some exceptions, survey soundings are generally deeper than the charted soundings. The figure below shows charted soundings overlaid on soundings from this survey. Soundings from this survey (blue) overlaid on US4AK52M (soundings in red). All soundings in meters. file:///M:/OPRR340KR21/Surveys/H13442/01_HDR/Working/Report/Original/H13442_DR/SupportFiles/Charted_Soundings.jpg US4AK52M 100000 4 2017-12-27 2017-12-27 No shoals or potentially hazardous features exist for this survey. No DTONs were submitted for this survey No charted features exist for this survey. No uncharted features exist for this survey. No channels exist for this survey. There are no designated anchorages, precautionary areas, safety fairways, traffic separation schemes, pilot boarding areas, or channel and range lines within the survey limits. No Aids to navigation (ATONs) exist for this survey. No Maritime Boundary Points were assigned for this survey. 12 bottom samples were assigned in this sheet. Samples were successfully obtained at all but one of the assigned locations. At one assigned location (57-50-36.21 N, 157-59-27.02 W) a sample was attempted but could not be retrieved. Three attempts were made at this location with no sample returned to the surface despite the sampler returning in a closed state on each, indicating it had made contact with the seafloor and successfully sprung shut. Most returned sand as the primary constituent. Pebbles and gravel were common secondary constituents. Samples were photographed but not retained. Refer to the FFF submitted with the survey deliverables for results. No overhead features exist for this survey. No submarine features exist for this survey. No platforms exist for this survey. No ferry routes or terminals exist for this survey. No abnormal seafloor or environmental conditions exist for this survey that have not already been discussed in this report. No present or planned construction or dredging exist within the survey limits. No new surveys or further investigations are recommended for this area. No new ENC scales are recommended for this area. As Chief of Party, field operations for this hydrographic survey were conducted under my direct supervision, with frequent personal checks of progress and adequacy. I have reviewed the attached survey data and reports. All field sheets, this Descriptive Report, and all accompanying records and data are approved. All records are forwarded for final review and processing to the Processing Branch. The survey data meets or exceeds requirements as set forth in the 2020 NOS Hydrographic Surveys Specifications and Deliverables, Hydrographic Survey Project Instructions and Statement of Work. This data is adequate to supersede charted data in their common areas. This survey is complete and no additional work is required with the exception of deficiencies, if any, noted in the Descriptive Report. Andrew Orthmann, C.H. Charting Program Manager 2021-12-31 Tide Station Recon Reports (Egegik and Pilot Point) 2021-06-21 9464874 Egegik Tide Station Install Report 2021-09-10 9464512 Dago Creek Tide Station Install Report 2021-09-11 Survey Outline Submittal 2021-10-15 Final Progress Report 2021-10-15 9464874 Egegik Tide Station One Day Removal Report 2021-11-06 9464512 Dago Creek Tide Station One Day Removal Report 2021-11-08 NCEI Sound Speed Data Submittal 2021-11-19 MMO Logsheets and Training Observer Log Submittal 2021-11-23 Coast Pilot Review Report 2021-12-06 9464874 Egegik Tide Station Removal / Tides Package 2021-12-12 9464512 Dago Creek Tide Station Removal / Tides Package 2021-12-14 9999778 Offshore Egegik GNSS Buoy Removal / Tides Package 2021-12-17