Water Quality Monitoring
Water quality monitoring to identify pollutants and their sources is critical for mitigating impacts from sewage. To recognize sewage pollution events, baseline conditions must be established and regularly monitored. Techniques for water quality monitoring vary, ranging from extensive laboratory analysis to real-time field tests. Water quality monitoring is typically done by local government agencies, but efforts are growing to expand capacity for monitoring that include partner organizations and local volunteers.
Sewage Pollution Indicators and Methods
The table below lists indicators used to identify and measure sewage pollution in the ocean. Test methods vary and the provided resources offer detailed methodologies for practitioners.
|Caffeine||Lab test (GC-MS)||>24 hours|
|DNA||Lab test (eDNA metabarcoding or fluorescence quantification)||Same day|
|DO (dissolved oxygen)||Field measurement||Real-time|
|Endocrine Disruptors (e.g., estrogen)||Lab test (GC-MS)||>24 hours|
|Enterococcus (FIB)||Lab test (culture quantification)||>24 hours|
|Chlorophyll a||Field measurement||Real time|
|Clostridium perfringens (FIB)||Lab test||>24 hours|
|Hydrogen Sulfide||Field measurement||Real time|
|Metals||Lab test||>24 hours|
|Nitrate||Field measurement||Real time|
|Nitrogen Isotopes||Lab test||>24 hours|
|Chemicals of Emerging Concern (CECs)||Lab test||>24 hours|
|Sterols||Lab test||>24 hours|
|Sucralose||Lab test (GC-MS)||>24 hours|
|Total Dissolved Solids (TDS) or turbidity||Field measurement||Real-time|
Water quality testing methods range from involved procedures, undertaken in a lab setting, to simple field measurements. For example, turbidity, an indicator of water clarity to understand the depth sunlight is able to penetrate, can be measured manually using a secchi disk or digitally using a conductivity meter, nephelometer, or photosynthetically active radiation sensor. These portable field measurement tools require maintenance and calibration, but enhance the ability to collect data in real time. Some of the more simplistic and affordable monitoring strategies, such as hydrogen sulfide (H2S) tests that indicate whether fecal indicator bacteria (FIB) are present in water, have increased community engagement with monitoring efforts, leading to improved behavior and sanitation systems in opens in a new windowTanzania.
See the Resources section for more detailed water quality monitoring methodologies for practitioners.
An emerging monitoring opportunity exists through data analysis, particularly coupled with increasing remote sensing and spatial imagery efforts. opens in a new windowPublicly available data may include algal blooms, coral bleaching events, opens in a new window sea temperature fluctuations, eutrophication potential, and, in some cases, combined with other geographic data, such as locations of sewage treatment plants, these data may provide managers with useful information to understand baseline conditions as well as create methods for monitoring changes over time. opens in a new windowHeal the Bay’s NowCast Beach Report Card, is a model to predict beach water quality in California, USA, and improves public awareness of contamination events.
There remains a need for innovative and cost effective measurement and reporting tools to identify sewage pollution. The opens in a new window Ocean Health Index is a project undertaken by NCEAS that presents ocean health scores based on threats and resilience. A data layer specific to sewage pollution in the ocean is in development and will be useful for data analysis and multi-scalar evaluations of the impacts of sewage pollution.