Navigable Area2003W00461CaliforniaChannel Islands, CaliforniaSanta Rosa Island400002003-06-202003-06-252019-09-27ESD-PHB-18California State UniversityPat IampietroResonSeabat8101Pacific Hydrographic BranchmetersAny 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 11N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.World Geodetic System (WGS) 1984Mean Lower Low WaterDiscrete ZoningProjected UTM 102018-10-122019-09-27Pacific Hydrographic BranchPat IampietroChief HydrographerSeafloor Mapping Lab at California State University Monterey BayPHBMarine Protected Areas (MPAs) are established in an effort to manage natural marine resources and limit anthropogenic impacts on marine ecosystems. Assessing the effectiveness of MPAs can be challenging. Monitoring species diversity between MPAs and control sites (open to standard fishing rules and regulations) of similar physical structure can aid in determining the ecological value of MPAs. The goal of this project was to map habitats within designated MPA sites and adjacent proposed control areas and evaluate habitat similarity between MPA and control sites in the Channel Islands Marine Protected Area Network. There were no products created for this survey.The horizontal datum for this project is NAD 83, the projection used is Universal Transverse Mercator (UTM) zone 11N. Differential GPS (DGPS) position data were generated by a Trimble 4700 GPS with differential corrections provided by a Trimble ProBeacon receiver. A TSS POS/MV heading and motion sensor provided heave, pitch, heading, and roll data. No additional information on vertical control was provided in supplied metadata. Bathymetric data were collected aboard the National Park Service's R/V Pacific Ranger using a Reson 8101 multibeam echosounder. Coastal Oceanographics Hypack software was used for survey design and execution. All raw data were logged using a Triton-Elics International (TEI) Isis data acquisition system. Water column sound velocity profiles collected using an AML SV+ sound velocity profiler. Bathymetric data were post-processed using CARIS HIPS hydrographic data cleaning system software. Soundings were corrected for vessel motion using TSS POS/MV data, variations in water column sound velocity using AML SV+ data, and adjusted to MLLW using predicted tide charts for the local region. Cleaning to remove erroneous soundings was completed in CARIS HIPS. Soundings were exported from CARIS HIPS as a decimated x,y,z ASCII text (shoal biased) with 3m, 100m, 300m, and 500m spacing. The 3m decimated x,y,z ASCII text is imported into Fledermaus. AverageGridder to generate 3m grid(s). The 3m Fledermaus grid (.asc) was imported into Spatial Analyst to generate a 3m bathymetry grid. The 3m bathymetry grid was used to process a Hillshade and a slope grid. The Hillshade will show as a greyscale and shows the shadows of features. The slope grid shown in color will highlight areas of high slope values in red and areas of low slope values in blue. Upon arrival at the Pacific Hydrographic Branch the data was imported into CARIS and a new .csar surface was created for branch review. An uncertainty layer was calculated for CATZOC B standards using the following formula: 1.0 + (0.02* Depth). W00461 is one of three surveys from the University of California in 2003. All three surveys were reviewed in succession and through junction comparisons on all three surveys, the reviewer found that the surveys from 2003 were approximately 2.5 meters shallower than its neighbors. Per the Vertical Alignment Policy, the surface for W00461 was shifted 2.5 meters deeper. In addition, this survey is no longer eligible to be used as a reference for future surface adjustments. Extreme caution should be made when using this survey as a junction. All data were reviewed for DTONs and none were identified in this survey.Seafloor Mapping Lab at California State University Monterey Bayhttp://seafloor.otterlabs.org/index.htmlIn general, the grids appear to show good internal consistency. There are some offsets seen in the bathymetric grid which could be due to tidal influences or motion artifacts (heave) in the data with up to 3 meters of difference. Sound speed artifacts could be the issue behind the vertical offsets seen in the grids. As the underlying soundings were not provided with the data set, therefore the reviewer could not confirm this hypothesis. Line by line there are vertical offsets. It is unknown that these vertical offsets between the said lines are due to water level issues or with other vessel configurations. Holidays do exist in the data. Generally they have been created due to poor overlap between lines. Survey W00461 and the charts in the area show very good agreement. In general, survey W00461 is shallower than charted data. Large holidays found in surface. file:///Q:/W00461_Santa-Rosa-Island-S-Pt/Office%20(PHB)/Working/Images/W00461_Holidays.pngThis survey does meet charting specifications and is adequate to supersede prior data.Due to the vintage of the current charts (partial bottom coverage surveys from 1900-1939) it is recommended that survey W00461 supersede previously charted data.