TerraSond Charting Program Manager2019-12-15Andrew Orthmann, C.H.This report, digital data, and all other accompanying records are approved. All records are hereby respectfully submitted for final review and acceptance.Field operations and data processing contributing to the completion of this survey were conducted under my direct supervision with frequent personal checks of progress, integrity, and adequacy.The survey data meets or exceeds the requirements set forth in the 2019 NOS Hydrographic Surveys Specifications and Deliverables document as well as the 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 this Descriptive Report.Survey Outlines2019-09-10MMO Training Logsheet and Observation Logs2019-09-12NCEI Sound Speed Data Submission2019-09-12Coast Pilot Report2019-09-13Tides and Water Levels Package - 9465419 Levelock2019-11-15Tides and Water Levels Package - 9465993 Ishkowik2019-11-15Tides and Water Levels Package - 9463502 Port Moller2019-11-16Tides and Water Levels Package - 9465203 Naknek2019-11-18Tides and Water Levels Package - 9465137 Cape Pierce2019-11-19Tides and Water Levels Package - 9465265 Kulukak Point2019-11-20Tides and Water Levels Package - AAAAAAA Cape Mendenhall2019-11-23Tides and Water Levels Package - BBBBBBB SW Kuskokwim Bay2019-11-23Tides and Water Levels Package - CCCCCCC Cape Corwin2019-11-27Refer 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.Both survey vessels were outfit for MBES data collection with similar survey equipment. The ASV-CW5 was equipped with a Reson SeaBat 7125 MBES while the Q105 used a Reson SeaBat 7101 MBES. Both vessels used Applanix POSMV 320 V5 (Wavemaster II) units for attitude and position measurements. Sound speed profiles were collected using a Valeport rapidPro SVT sensor (deployed using a Teledyne Oceanscience RapidCast system) from the Q105 only.Teledyne RESONMBESSeaBat 7125 SVTeledyne RESONMBESSeaBat 7101ApplanixPositioning and Attitude SystemPOS MV 320 v5Teledyne OceanscienceSound Speed SystemrapidCASTValeportSound Speed SystemrapidPro SVTThe Qualifier 105 (Q105) is a 32 m aluminum-hull vessel owned and operated by Support Vessels of Alaska. 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 BMPG tide gauges, conduct sound speed casts, and deploy/recover 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 L3-Harris ASV. The ASV was operated in an unmanned but monitored mode, collecting multibeam data in close proximity to the Q105.file:///M:/OPRR341KR19/Surveys/H13251/Processed/Reports/Survey/Descriptive_Report/Report/SupportFiles/Vessels.jpgASV-CW5 (foreground), and Q105 (background).ASV-CW55.50.5Qualifier 105321.8NOAA Extended Attribute Files V2019.3NOAA Extended Attributes were used for the Final Feature File (FFF) submitted with the survey deliverables.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 2019 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 2019 HSSD. The surface was finalized, and designated soundings were applied where applicable. Horizontal projection was selected as UTM Zone 3 North, NAD83. 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 (V2019.3). Georeferenced multibeam backscatter mosaics (Geotif format in NAD83 UTM Zone 3N, 1 m resolution) were also produced and are provided with the survey deliverables. One mosaic was produced for each vessel. Note that backscatter processing and mosaic generation was not a requirement and the mosaics are provided as-is. The mosaics may have flaws or holidays which could be addressed through further processing. However, they are of sufficient quality to show the relative changes in seafloor type across the survey area.MBES Set Line SpacingH13251_MB_4m_MLLW_FinalCARIS Raster Surface (CUBE)NOAA_4m4080MBES Set Line SpacingH13251_MBAB_1m_ASV_400kHz_1of1MB Backscatter MosaicN/A1080MBES Set Line SpacingH13251_MBAB_1m_Q105_240kHz_1of1MB Backscatter MosaicN/A1080All sounding systems were calibrated as detailed in the DAPR.Deviations from the Corrections to Echo Soundings section of the DAPR are itemized below. Note that in all cases final data is within specifications. Delayed Heave Exceptions The following lines could not have Delayed Heave loaded. This was usually due to a software crash or other issue causing logging to the associated POS file to cease early. Real-time heave was used instead during all processing phases including SVP correction, Compute GPS Tide, and Merge on these lines. 0709-ASV-CW5-211-F3EW00000_-_0001 0737-ASV-CW5-212-F4NS00200_-_0001 0738-ASV-CW5-212-F4NS00200_-_0001 0284-ASV-CW5-191-F1NS03400_-_0001 0285-ASV-CW5-191-F1NS03400_-_0001 0286-ASV-CW5-191-F1NS03600_-_0001 0287-ASV-CW5-191-F1NS03600_-_0001 0288-ASV-CW5-191-F1NS03800_-_0001 GPS Height Smoothing The following lines were loaded with GPS heights that had been smoothed to remove spikes and/or short-term drifts using a 6-minute moving average. The smoothed GPS height data was loaded using CARIS' Generic Data Parser utility from text files at a rate of 1 Hz, which are included with the survey deliverables. Since the smoothing process removed heave data from the GPS record, the Apply Dynamic Heave option was set to "None" during computation of GPS Tide for these lines. More details are available in the DAPR. 0735-ASV-CW5-212-F3EW00000_-_0001 Use of Applanix Smart Base (ASB) ASB was used instead of the project default PP-RTX post-processing method in Applanix POSPac MMS software to improve vertical agreement on the following lines. Vessel ASV, JD211, all lines with prefix 689 through 709All equipment and survey methods were used as detailed in the DAPR.file:///M:/OPRR341KR19/Surveys/H13251/Processed/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13251_Junctions.jpgImage showing survey junctions.Terrasond, Ltd.2019SW40000H13250Agreement between the two surveys is excellent, with a mean difference of 0.00 m with a standard deviation of 0.09 m. At least 99.5% of overlapping grid cells compare within the allowable TVU for the depth.file:///M:/OPRR341KR19/Surveys/H13251/Processed/Reports/Survey/Descriptive_Report/Report/SupportFiles/H12164_Difference.jpgImage showing difference in meters (black soundings) between this survey and H12164, completed in 2010.Terrasond, Ltd.2010NE10000H12164H13251 was compared to a combined MBES and VBES surface for H12164 downloaded from NOAA NCEI, "H12164_MBVB_4m_MLLW_combined.bag". Agreement is extremely poor between the surveys. The mean difference is 1.14 m with a standard deviation of 4.4 m. Only 4% of grid cells agree within allowable TVU for the depth. Differences range widely, from -8.078 m (this survey shoaler) to 7.339 m (prior survey shoaler), showing a shift to the west in the river channel in the area of the junction. The junction is at the entrance to the Kuskokwim River in an extremely dynamic and changeable area. The DR for H12164 also noted bottom changes observed during the field work for that survey in 2010. Drastic change during the 9 years between the surveys is therefore not unexpected.NOAA's "Gridded Surface Comparison V19.4" utility was used to complete the junction comparisons. The utility differences the surfaces from the junctioning surveys and generates statistics, including the percentage of grid cells that compare to within allowable TVU for the depth. 4 m-resolution CUBE surfaces were used for all Current surveys.All equipment and survey methods were used as detailed in the DAPR.Bottom Changefile:///M:/OPRR341KR19/Surveys/H13251/Processed/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13251_BottomChangeExample.jpgExample of bottom change (at 59-47-51 N, 163-04-45 W) in this survey. Soundings colored by day -- dark green on JD191, light green on JD218. Vertical bust of up to 1.6 m is due to bottom change over the 27 day period.Bottom change is evident throughout this survey, especially when data was collected days to weeks apart. The survey area is a sediment deposition area at the mouth of a major river. Large tidal and riverine currents flow across the area and form transitory features such as channels, sandbars, and submerged shoal areas. Sandwaves and related signs of sediment transport are readily apparent in the MBES data. As a result, vertical and horizontal busts that exceed allowable TVU occur periodically in the dataset. These changes commonly approach 0.4 to 0.5 m, with some change observed of up to 1.6 m (example below). No attempt was made to edit or otherwise manually choose a seafloor in areas where this occurred.Sound Speed ErrorSound speed or refraction error, observed as cupping in the outer beam data, was observed periodicially in this data set. This was not a major issue on this survey but adversely affects some lines by up to 0.20 m, which an effect on final surfaces which is within allowable TVU for the depth.Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR.Effort was made to ensure crosslines 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 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 normally ran parallel lines, crosslines were often collected in sets whenever both vessels were in simultaneous operation. Crosslines were also occasionally collected while transiting across the survey area to reach a different survey priority such as bottom sample locations or infills, leading to crosslines that were diagonal to the direction of mainscheme lines. Since the area was uncharted, reconnaissance lines that followed the main channels were usually collected first before proceeding with collection of mainscheme lines that ran perpendicular to the channels. These reconnaissance channel lines sometimes doubled as crosslines. Use of these lines as crosslines as well as the collection of crosslines in two-vessel sets led to incidental collection of additional crossline LNM beyond the required 8% of mainscheme. 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. 0982-ASV-CW5-219-Shallows-XL -- 100.0% pass 1034-ASV-CW5-219-F2EW02400 -- 100.0% pass 0708-ASV-CW5-211-AIS -- 100.0% pass 0772-ASV-CW5-212-F4NS07200 -- 100.0% pass 0702-ASV-CW5-211-F4EW01200 -- 99.7% pass 0689-ASV-CW5-AIS -- 99.5% pass 0098-ASV-CW5-188-F2NS03200 -- 98.4% pass Results: Agreement between the 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.ASVN/A0.0252.81N/AQ105N/A0.0252.81N/A0ERS via ERTDM0.13The NOAA-provided ERTDM model has an uncertainty of 0.13 meters. Refer to Appendix I for correspondence. The uncertainty layer of the final surface was examined in CARIS HIPS. Uncertainty falls in the range of 0.263 to 0.657 m. Most grid cells are on the lower end of the uncertainty range, approximately 0.270 m. The larger values were observed to be on sand wave features or other areas of highly variable seafloor such as steep cut banks of shoals and sandbars as well as areas exhibiting bottom change, where many soundings of different depths contribute to the depth value of the relatively large 4 m grid cell resulting in a higher standard deviation of soundings contributing to the grid cell. The final surface was also analyzed in QCTools (3.1.2), which reported that greater than 99.5% of grid cells in the final surface have uncertainty within allowable TVU for the depth.GPS Vertical BustsVertical busts attributable to GPS positioning error between crosslines or overlapping mainscheme are apparent periodically in the data set. These are normally less than 0.15 m, with extreme cases showing up to 0.30 m of vertical separation. However, all crosslines--including those exhibiting or crossing areas exhibiting vertical busts--pass within IHO Order 1a, and final surfaces are within allowable TVU for the depth.Sound speed profiles or "casts" were acquired aboard the Q105 while underway with a Teledyne Oceanscience RapidCAST system, which utilized a Valeport rapidPro SVT sound speed profiler. 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 favored to ensure that changes across the full water column were measured. The cast data was used to correct the sounding data for both vessels, using the "nearest in distance within time" (set to 4 hours) within CARIS HIPS.2 hoursPOSMV Dropouts (ASV-CW5)Approximately every 24 hours during survey operations the POSMV on the ASV-CW5 would drop offline. This was observed as sudden output of obviously erroneous data by the POSMV such as excessive vessel speeds, incorrect headings, and erroneous motion, followed by an automatic reinitialization of the POSMV. The issue would often repeat 1-2 additional times over a 5-10 minute period before resuming normal operations for an additional 24 hours. No definite cause was determined. When this occurred the ASV-CW5 would break offline, note the issue in the acquisition log, circle back and proceed with rerunning the affected section of line. The affected section of line was subsequently rejected in processing. Since affected data was rejected and reran there is no adverse affect on final deliverables.Shoals or potentially hazardous features exist for this survey, but were not investigated. Shoals, either exposed or submerged at low water, are common inshore of the 3.5 m depth limit. Areas inshore of 3.5 m should be clearly marked on the charts as unsurveyed or otherwise hazardous for navigation. No DTONs were submitted for this survey. The CTNARE (CAUTION AREA) objects on the ENCs noting the region as a "Changeable Area" should be retained.No uncharted features exist for this survey.US3AK84M2000002019-10-08122018-08-07US4AK85M1000002019-10-08122019-09-09US2AK95M15340762019-10-1692018-08-20The 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 finalized BASE 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. Results are discussed below. It is recommended that in all cases of disagreement this survey should supersede charted data. US3AK84M - The area is mostly uncharted on US3AK84M with little for comparison. There is minor overlap with DEPARE (Depth Area) objects on the ENC that are encoded with a depth of -1.8 to 0 m; these should be updated where they intersect this survey. There is a small amount of overlap on this survey's NE side. No soundings directly overlap. Nearby soundings differ by 2-3 m. It appears the river channel and corresponding mid-river shoal has shifted westward by up to 800 m in this area. However, this survey had insufficient overlap with charted data here to delineate the extent of the shift. US4AK85M - Results of this comparison are similar to US3AK84M. The area is mostly uncharted on US4AK85M with little for comparison. There is minor overlap with DEPARE (Depth Area) objects on the ENC that are encoded with a depth of -3 to 0 m; these should be updated where they intersect this survey. There is a small amount of overlap on this survey's NE side. No soundings directly overlap. Nearby soundings agree within 0.2 m in a relatively shallow area at 59-59-15.0 N, 162-25-50.8 W to as poorly as 6.3 m of difference at 60-00-21.6 N, 162-26-13.0 W, where the chart shows a 5.7 m depth nearby while this survey shows approximately 12 m. The area of the 5.7 m charted sounding appears to have deepened significantly, and the river channel and associated mid-river shoal have migrated to the west. US2AK95M - The area is uncharted on this small scale chart with no depths to compare. This survey intersects a depth area (DEPARE) object on the ENC with a depth range of -3.1 to 0.0 m. The DEPARE object extents should be modified based on this survey. USCG Notice to Mariners (NM) and USCG Local Notice to Mariners (LNM) for District 17 from week 26/2019 through 34/2019 were checked and no items were found that affected the survey area. Note that ENC metadata and non-specific geographic area objects on the ENCs that overlap the survey area were not investigated.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 charted features exist for this survey.No overhead features exist for this survey.Four bottom samples were assigned via the PRF. All assigned locations were in unnavigable areas. Therefore the assigned positions were shifted to the nearest navigable location. Three samples were achieved, which returned primarily black to gray soft mud. A fourth sample was attempted at 59-53-52.616 N, 162-34-14.079 W. Three attempts were made at the location but no sample could be obtained. Refer to the FFF submitted with the survey deliverables for results.The 3.5 m depth contour was reached well offshore in this area. As a result, despite additional effort by the field crew with the equipment available on site, a large gap between survey data and the communities of Kwigillingok and Kongiganak remains, and the final survey extents resulted in three disconnected polygons which do not provide nearshore soundings to connect a surveyed route with the Kuskokwim River. Additional work is therefore recommended inshore of 3.5 m in the vicinity of the two communities as well as between the disconnected survey polygons. AIS data indicates barges navigate between these areas, likely timed at high tide--during which shoals appear to largely be submerged and navigable to very shallow drafted vessels. Depths of 0 m MLLW could be achieved with appropriate equipment and methodology, such as a skiff or other small vessel deployed during good weather from a larger support vessel, and tasked with performing transects with VBES timed around high water.As described earlier in this report, the area is in the depositional zone of a major river. Migrating sandbars, shoals, and channels are common. Sandwaves are evident on the seafloor in many areas. During survey operations, currents of 2-3 knots were commonly experienced during the ebb and flood portions of the tidal cycle. Currents were generally oriented northeast-southwest, running parallel to the channels. Greatest currents were on the NE part of the survey at the entrance to the Kuskokwim River on ebb tides.No platforms exist for this survey.No present or planned construction or dredging exist within the survey limits.No Maritime Boundary Points were assigned for this survey.No ferry routes or terminals exist for this survey.No submarine features exist for this survey.No Aids to navigation (ATONs) exist for this survey. Charted buoys on the large scale charts were outside the survey limits.No new insets are recommended for this area.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/. Products created during office processing were generated in NAD83 UTM 3N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.2019metersNavigable AreaAndrew Orthmann2019-08-132019-07-07Multibeam Echo SounderMultibeam Echo Sounder Backscatter2019-05-10UTCPacific Hydrographic BranchTerrasondKuskokwim Bay, AKOPR-R341-KR-19Kuskokwim Bay, AK & VicinityContractor6Alaska10000United StatesKwigillingok to KulvagavikH13251Port Moller9463502Cape Pierce9465137Naknek9465203Kulukak Point9465265Levelock9465419Ishkowik9465993Cape MendenhallAAAAAAASW Kuskokwim BayBBBBBBBCape CorwinCCCCCCCERS via ERTDMR341KR2019_ERTDM_NAD83-MLLWAll soundings were reduced to MLLW using the ERTDM NAD83 to MLLW separation model grid file provided by NOAA using ERS methodology. Discrete tide zones were generated using project gauge data but were used for comparison purposes only. A comparison between the provided ERTDM model and a ERZT model created using the tide zones was undertaken. There is generally good agreement between the models, with project-wide agreement averaging 0.033 m with a standard deviation of 0.271 m. See the HVCR for additional information.Mean Lower Low WaterSmart BaseRTXThe Trimble PP-RTX subscription-based correction service within POSPac was used for final positioning. Results were good overall, usually at 0.10 m or better vertically. Applanix Smart Base (ASB) was used on a small number of lines (described previously in this report) to improve vertical matchup. Refer to the DAPR for additional details.Projected UTM 3The survey vessels were configured to receive RTK-level correctors via Hemisphere AtlasLink SBAS (L-band) receivers. This was utilized throughout the survey on the ASV-CW5 but only briefly at the start of operations on the Q105. However, all real-time correctors were superseded in processing with PPK correctors from Applanix POSPac. Refer to the DAPR for additional detail.The FAA Wide Area Augmentation System (WAAS) was used for real-time positioning on the Q105 for the majority of the survey. These positions were superseded in processing with PPK correctors from Applanix POSPac, as described in the DAPR.North American Datum 1983Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.file:///M:/OPRR341KR19/Surveys/H13251/Processed/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13251_Extents.jpgImage showing survey extents.60.0118666667163.13686138959.7856305556162.427508333The project area is located in southwest Alaska near the entrance to the Kuskokwim River in a relatively remote area of the Arctic. The area was uncharted at the time of this survey. Vessel traffic in the region largely consists of barges that are transiting to or from Bethel (population 6,456), the hub for SW Alaska which is located up the Kuskokwim River, as well as native communities in the region. The area is heavily influenced by current and sediment transport from the Kuskokwim River. As a result it is relatively shallow with shifting shoals, sandbars, and channels. Sand and mud are the predominant bottom types. The area is normally not navigable during winter due to discontinuous sea ice in the bay and river ice flows from the Kuskokwim River. The area is open and exposed in all directions except the north. Bathymetric data collection was carried out in July and August of 2019 under project OPR-R341-KR-19, with final processing and reporting carried out from September through December, 2019. Supporting tide data was acquired from June through October, 2019. Work was completed concurrently with other assigned areas within Kuskokwim Bay and near Nunivak Island, and done in accordance with the Hydrographic Survey Project Instructions (dated May 10th, 2019) and the NOS Hydrographic Surveys Specifications and Deliverables (HSSD), March 2019 edition.Data was successfully acquired to the survey limits or the NALL, whichever was encountered first. The NALL for this survey was the 3.5 m depth limit. 3.5 m water depth was achieved at the required line spacing (200 m). Additional data was acquired inside the NALL per request from NOAA OPS, discussed in the coverage section below. Two lines were intentionally extended outside the assigned survey limits on the NE part of the survey for approximately 1 km. This was done to achieve good overlap with prior junctioning survey H12164 from 2010.The overall project OPR-R341-KR-19 is intended to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products in the U.S. Arctic to support commerce in the region. Automatic Identification Systems (AIS) traffic patterns feeding the Hydrographic Health model, along with direct user feedback helped to define the survey area in Kuskokwim Bay, Southwest Alaska. This area is largely unsurveyed and contains mud flats, uncharted shoals, and poorly modeled tides, forcing vessel traffic between the Kuskokwim River and northern communities to take an extended southerly route to stay in safe water. Surveying these areas within Kuskokwim Bay will allow for shorter routes, increasing the safety and efficiency of vessel traffic. This work will also directly support the maritime services available to the native communities of Kwigillingok and Kongiganak. Furthermore, this project will provide support for other NOAA Hydrographic surveys and regional tidal products by installing temporary water level measuring stations in the vicinities of Cape Newenham and Nushagak Peninsula located in Bristol Bay. Survey data within the survey limits is intended to supersede all prior survey data within the project limits.2019-07-072019-07-102019-07-112019-07-302019-07-312019-08-062019-08-072019-08-13ASV-CW514.30000000153.3Qualifier 105000000005.2914.30000000158.539.9000file:///M:/OPRR341KR19/Surveys/H13251/Processed/Reports/Survey/Descriptive_Report/Report/SupportFiles/H13251_Coverage.jpgImage showing survey coverage.file:///M:/OPRR341KR19/Surveys/H13251/Processed/Reports/Survey/Descriptive_Report/Report/SupportFiles/35_m_depth_limit.jpgFigure showing the approximate 3.5 m depth limit, which was located well offshore of the communities of Kwigillingok and Kongiganak. Additional data was acquired inshore of the 3.5 m limit.file:///M:/OPRR341KR19/Surveys/H13251/Processed/Reports/Survey/Descriptive_Report/Report/SupportFiles/Kwigillingok_Soundings.jpgFigure showing the approach to Kwigillingok. Soundings (blue, in meters) were aquired inshore of the 3.5 m depth limit at high tide in order to search for deeper water to better develop the approach.file:///M:/OPRR341KR19/Surveys/H13251/Processed/Reports/Survey/Descriptive_Report/Report/SupportFiles/Kongiganak_Soundings.jpgFigure showing the approach to Kongiganak. Soundings (blue, in meters) were acquired inshore of the 3.5 m depth limit at high tide in order to search for deeper water to better develop the approach.Coverage requirements were met. 5,761 linear nautical miles (LNM) was acquired project-wide, which exceeded the required minimum of 5,301 LNM. The overage of 460 LNM (about 8.7% of required LNM) was collected to compensate for any inefficiencies incidental to the execution of line collection such as excess crossline LNM, data acquired on turns in order to scout depths between lines in shallow water, or lines ran closer together than required. Kwigillingok and Kongiganak Approaches Coverage in this sheet was extremely depth limited. Though the desired outcome was to survey the approaches to Kwigillingok and Kongiganak to assist the barge traffic which services the communities, the NALL (3.5 m depth limit in this area) was reached up to 4 NM offshore of these communities. This information was relayed to OCS OPS who requested a best-effort to acquire additional soundings inshore of the 3.5 m in order to find deeper water. Each area was revisited on separate high tides. The ASV-CW5 was pushed inshore of the 3.5 m depth limit as shallow as safely possible within its radio range limits (about 3 km) from the Qualifier 105, which had to wait in deeper water due to its draft. Though MLLW depths generally less than 1 m were achieved, no water of significantly deeper depth was found. Relative to the 3.5 m depth limit, the effort advanced the survey coverage an additional 1.2 NM towards Kwigillingok and 0.5 NM towards Kongiganak but still left a relatively large gap between this survey and the communities. Note that effort was made to fill in the area inside of 3.5 m to the project standard of 200 m spacing as timing of high water allowed, but since survey inside of the NALL was not required some gaps in the spacing were intentionally left at the approach to Kwigillingok. Correspondence is available in Appendix II. Images below show this area.Set Line Spacing MBES at 200 m (Refer to HSSD Section 5.2.2.4 Option A)All waters in survey area within Sheet 6Complete 5301 LNM. Transit mileage, system calibration mileage and data which do not meet HSSD specifications shall not count towards the completion of the LNM requirement. Notify the COR/Project Manager upon nearing completion of LNM requirement. The final survey area shall be squared off and ensure the full investigation of any features within the surveyed extent.All waters in survey areaThe entire survey is adequate to supersede previous data.