Rivers (2016 Final WQA IR Assessment)

All rivers and streams identified in the 2016 Virginia 305(b)/303(d) Water Quality Assessment. Line work and attributes should not be altered except by the developer (DEQ). This dataset constitutes the United States Environmental Protection Agency (EPA) approved digital version of the assessment hydrology for Virginia. Attributes assigned to each water segment are based on attributes associated with the ID305B (assessment unit ID) entered in the statewide water quality assessment database. QA/QC checks are performed on the database prior to linking attributes to the GIS data, however errors may still occur. Please direct any questions about attribute accuracy to the Data Distributor. The geospatial product is maintained and updated by VA DEQ each assessment cycle (biennially) using the most current NHD product where revisions were made to Virginia waters, the most recent aerial photography provided by the Virginia Geographic Information Network (VGIN), and by freehand digitizing where necessary. Metadata is provided in the data Fact Sheet which contains contact information, process steps, attribute descriptions, and distribution information.本数据集涵盖2016年弗吉尼亚州305(b)/303(d)水质评估中识别的全部河流与溪流。仅允许开发者（弗吉尼亚州环境质量部，DEQ）对要素线与属性进行修改，其余主体不得擅自改动。本数据集为经美国环境保护署（EPA）批准的弗吉尼亚州评估水文数据数字化版本。分配至每个水体河段的属性，均基于全州水质评估数据库中录入的、与ID305B（评估单元ID）相关联的属性信息。在将属性关联至地理信息系统（GIS）数据前，已对数据库开展质量保证与质量控制（QA/QC）核查，但仍可能存在疏漏。若对属性准确性存有疑问，请联系数据分发方咨询。本地理空间产品由弗吉尼亚州环境质量部（VA DEQ）在每个评估周期（每两年一次）内进行维护与更新，更新依据包括：针对弗吉尼亚州水体完成修订的最新版全国水文数据集（NHD）、弗吉尼亚州地理信息网络（VGIN）提供的最新航空影像，以及必要时的手动数字化作业。数据集元数据详见数据情况说明书（Fact Sheet），该说明书包含联系方式、处理流程、属性说明与分发信息。