Drinking Water Contaminant

The CalEnviroScreen is a mapping tool developed by the California Office of Environmental Health Hazard Assessment to identify communities in California (at the census tract level) that are most affected by pollution sources. The tool uses indicators to measure environmental conditions. Drinking water contaminant is an environmental effects indicator, which show the locations of toxic chemicals in or near communities. From CalEnviroScreen: What is drinking water contamination? Most drinking water in California meets requirements for health and safety. However, the water we drink sometimes becomes contaminated with chemicals or bacteria. Both natural and human sources can contaminate drinking water. Natural sources can be found in rocks and soil or come from fires. Human sources include factories, sewage, and runoff from farms. Poor communities and people in rural areas are exposed to contaminants in their drinking water more often than people in other parts of the state. Why is this indicator included in CalEnviroScreen? Numerous chemical and bacterial contaminants are routinely detected in the drinking water in California. Nitrate from fertilizer or animal manure can leach into groundwater and contaminate wells. Nitrate can cause a blood condition in infants called blue baby syndrome (methemoglobinemia) and may cause birth defects and miscarriages. Arsenic, a common contaminant, occurs naturally in some rocks and soil and is often found in groundwater in California. Arsenic can cause cancer. How do we measure drinking water contaminants in CalEnviroScreen 4.0? The indicator combines information about 14 contaminants and 3 types of water quality violations that are sometimes found when drinking water samples are tested. We calculated average concentrations for the contaminants in each water system. To calculate the metric, we matched up the water quality calculation with drinking water system boundaries. A complete description of the Drinking Water Contaminants indicator can be found in the CalEnviroScreen 4.0 report. More information on the drinking water indicator: Methodology for a Statewide Drinking Water Contaminant Indicator (CalEnviroScreen 3.0) See downloads Drinking Water contaminant results by census tract (Microsoft Excel Spreadsheet) for 4.0: Average concentrations and percentile scores for each contaminant used to calculate the overall drinking water indicator. See downloads Drinking Water contaminant results by water system or Public Land Survey System (PLSS) section (Microsoft Excel Spreadsheet) for 4.0: Average concentrations for each contaminant in the drinking water indicator by community water system or PLSS section. See downloads Drinking water service boundaries were extracted from the California Environmental Health Tracking Program's Water Boundary Tool. Currently hosted by the State Water Board's System Area Boundary Layer (SABL) tool. Where can I find more information on drinking water quality? Drinking Water Systems with Violations Tool (For more information see the SAFER, Safe and Affordable Fund for Equity and Resilience, Drinking Water Site) To monitor progress in achieving the human right to water, OEHHA released CalHRTW 1.0 Human Right to Water Report and Tool in January 2021, which assesses the status of water quality, accessibility, and affordability across California. State Water Resources Control Board: My Water Quality U.S. Environmental Protection Agency (USEPA): Water on Tap

加州环境筛查工具（CalEnviroScreen）是由加州环境健康危害评估办公室（California Office of Environmental Health Hazard Assessment, OEHHA）开发的绘图工具，用于识别加利福尼亚州内以普查区（census tract）为统计单元的、受污染源影响最为严重的社区。该工具依托各类指标衡量环境状况，其中饮用水污染物指标属于环境影响类指标，用于呈现社区内部及周边有毒化学物质的分布点位。

从CalEnviroScreen官方说明来看：什么是饮用水污染物？加利福尼亚州绝大多数饮用水均符合健康与安全标准，但日常饮用的水有时会受到化学物质或细菌的污染。污染物来源可分为自然源与人为源两类：自然源包括岩石、土壤中的天然污染物，或是火灾引发的污染；人为源则涵盖工厂排污、污水处理设施排放以及农田径流。贫困社区与农村地区的居民，相较于该州其他区域人群，更频繁地接触到饮用水中的污染物。

为何将该指标纳入CalEnviroScreen？加州饮用水中常能检测到多种化学与细菌性污染物。化肥或畜禽粪便产生的硝酸盐会渗入地下水，污染水井。硝酸盐可引发婴儿的高铁血红蛋白血症（蓝婴综合征），还可能导致出生缺陷与流产。砷作为常见污染物，天然赋存于部分岩石与土壤中，常存在于加州地下水中，可诱发癌症。

CalEnviroScreen 4.0版中饮用水污染物的测算方式是怎样的？该指标整合了14种污染物与3类水质违规事件的相关信息，这些信息均来自饮用水样本检测结果。研究人员计算了各供水系统内污染物的平均浓度，为测算该指标，将水质计算结果与供水系统边界进行了匹配。饮用水污染物指标的完整说明可参阅《CalEnviroScreen 4.0报告》。

关于饮用水指标的更多资料：《全州饮用水污染物指标方法论（CalEnviroScreen 3.0版）》
下载资源1：按普查区划分的饮用水污染物结果（Microsoft Excel 电子表格）：用于展示用于计算整体饮用水指标的各类污染物的平均浓度及百分位数得分，适用于4.0版本。
下载资源2：按供水系统或公共土地测量系统（Public Land Survey System, PLSS）分区划分的饮用水污染物结果（Microsoft Excel 电子表格）：用于展示各社区供水系统或PLSS分区内，饮用水污染物指标中各类污染物的平均浓度，适用于4.0版本。
饮用水服务边界数据源自加州环境健康追踪计划的供水边界工具，目前由加州州水务委员会的系统区域边界层（System Area Boundary Layer, SABL）工具托管。

何处可获取更多饮用水水质相关信息？《存在违规行为的饮用水系统工具》（更多详情可参阅公平与韧性安全可负担基金（Safe and Affordable Fund for Equity and Resilience, SAFER）饮用水站点）
为监测饮用水人权目标的推进进程，OEHHA于2021年1月发布了《CalHRTW 1.0饮用水人权报告与工具》，该报告及工具对加州全境的水质、可及性与可负担性现状开展了评估。
加州水资源控制委员会：我的水质（My Water Quality）
美国环境保护署（United States Environmental Protection Agency, USEPA）：自来水安全（Water on Tap）