Beach & Coastal Health

How Are We Doing?

Beach and coastal health received an equally positive and equally negative rating because the number and duration of beach closures increased in 2020. Closures caused by impacts from the Tijuana River increased by over 300 beach mile days in 2020, representing a 30% increase from 2019 levels. The number of water quality events, excluding impacts from the Tijuana River, decreased from 77 beach mile days in 2019 to 45 beach mile days in 2020, which is a 42% decrease. These figures do not include beach and coastal health warnings that occur across all San Diego County Beaches for 72 hours after rainfall.

Beach and coastal health is greatly influenced by human activity on land and often the greatest impact is a result of changes that occur upstream. Dynamic impacts from rainfall runoff as well as infrastructure failures for sewage and wastewater treatment can directly and negatively impact beach and coastal health.

In addition to beach closures impacted by coastal water quality, the San Diego coastline is facing a suite of climate impacts such as increased flooding events, sea level rise and coastal erosion as well as potential threats and changes to the region’s coastal ecosystems.

Want to know more about what we're measuring?

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Equally positive and negative changes from 2019 to 2020

What Are Beach Mile Days?

Beach Mile Days (BMD) are calculated by multiplying the distance of the beach posted or closed by the number of days of the posting or closure. This ensures that a closure to a small section of beach is weighted differently in the overall total to a closure of a large section of beach.

The Tijuana River runs along the border between the United States and Mexico. Originating in Mexico, the river flows to the Pacific Ocean on the southern edge of San Diego County. Water treatment facilities along the river are often overrun with sewage and trash which ends up in the ocean and significantly impacts the quality of the water in San Diego's southern beaches. There was a substantial increase in sewage flows from the Tijuana River in 2020, correspondingly, beach closures resulting specifically from the Tijuana River increased from 974 beach mile days in 2019 to 1390 beach mile days in 2020, which is a 30% increase

Looking at water quality impacts not associated with the Tijuana River (the blue and red columns in the chart above), beach closures in San Diego County decreased from 14 beach mile days in 2019 to 2 beach mile days in 2020. Separately, beach and coastal health advisories, issued when bacteria levels exceed health standards, decreased from 63 beach mile days in 2019 to 43 beach mile days in 2020.

The San Diego County Department of Environmental Health issues rain advisories in response to significant rainfall events that can bring urban runoff into the ocean and cause bacteria levels to rise. The County warns beachgoers to avoid water contact during rain and for 72 hours following the rain event.

Sea level rise will exacerbate the effects of coastal flooding, which we already experience during high tides and storm surges, and lead to further beach erosion as well as runoff and drainage from intense storms.

Why is Beach & Coastal Health Important?

High quality of life means the region boasts a thriving economy and a healthy environment accessible to all in the community.

  • Environment: Beach and coastal health is greatly influenced by human activity on land; as a result these environments need to be dynamically monitored. The San Diego region is home to 11 main watershed systems, all of which drain into the Pacific Ocean. Based on San Diego Coastkeeper, stormwater runoff especially during the wet season can overwhelm San Diego coastlines by dumping urban pollutants such as motor oil, pesticides, pet waste, fertilizers, etc. into the ocean as the rainfall makes its way through the network of coastal canyons and watersheds. Such pollutants coupled with marine debris (e.g. plastic, glass, cigarette butts) that are intentionally or unintentionally discarded on beaches and in the water can significantly affect the quality of ocean water and consequently the health and wellbeing of humans and marine life. Capturing stormwater runoff would make a significant positive impact on the quality of beach water as well as local usable water supply.
  • Economy: Biodiversity of marine life has been threatened by pollutants such as plastic which has a direct economic impact on coastal communities such as San Diego who depend on the ocean for food, tourism, and recreation. Moreover, the cost of healthcare associated with poor quality of beach water in Southern California amounted to $20 to $50 million dollars. A healthy coast also means a healthy coastal economy and commercial fisheries are an important part of this economy. In 2011, approximately $201 million dollars in ex-vessel revenue (the amount paid directly to fishermen) came from commercial fishery landings, and more than 120,000 jobs on and off the water were supported by the state's seafood industry (NOAA 2011). Fishing communities are also an important part of California’s maritime heritage and economy and its coastal and ocean ecosystems. Viable commercial fisheries require not only healthy marine resources and habitat, but also people and businesses to support fishing activities. In 2019, California Sea Grant developed the California Commercial Fishing Apprenticeship Program which was developed to help the fishing industry adapt in a changing climate. 
  • Equity: Consistently, communities with high concentrations of poverty that are closer to U.S. Mexico's borders such as Imperial Valley are exposed to poor beach water quality due to sewage contamination from the Tijuana River. County of San Diego Department of Environmental Health’s Beach and Bay Water Quality Monitoring Program provides water testing, outreach, education and also up-to-date advisories on beach water quality along San Diego’s coastline. 

Want to learn more? Watch the Voice of San Diego's San Diego 101 video on how the Tijuana River Sewage crisis affects the region's beaches and coastline. San Diego 101 is a series from Voice of San Diego made to educate San Diegans about some of the most important issues that shape our region.

Regional Response


The San Diego Unified Port District completed the Sea Level Rise Vulnerability Assessment & Coastal Resiliency Report in 2019 to comply with California Assembly Bill 691, which requires a trustee of state tidelands to assess the area for potential inundation due to sea-level rise (SLR) and for proposing plans to protect and preserve at-risk areas. San Diego is especially at risk given its location on the coast. The vulnerability assessment projects impacts and damages of SLR for 2030, 2050, and 2100. If we do nothing to stop the rapidity of rising sea levels, we could be facing $68,500,000 in damages by 2050.

In 2019, the City of San Diego completed the State Lands Sea Level Rise Vulnerability Assessment. The City’s report addresses the impacts of sea level rise on the granted public trust lands as required by California Assembly Bill 691. It is important to note that these lands represent only a small subset of the City’s jurisdiction. To continue to address coastal resilience, the City of San Diego will be completing additional vulnerability assessments that will consider the entirety of the City’s jurisdiction as well as additional climate change related hazards, such as wildfire and extreme heat.


The Surfrider Foundation’s Blue Water Task Force performs supplementary coastal water quality testing in Imperial Beach, Coronado, and Baja. The data collected is available online and provides information to public agencies, environmental researchers, beach communities and beach-goers. The Blue Water Task Force features an interactive map showing beaches along the west coast of California. Users can click on specific beaches and obtain information on water quality data and learn whether or not it is safe to swim there.

The California Department of Public Health maintains a Toxic Phytoplankton Observations Map, accessible to the public. This map helps to inform beachgoers of potential threats from coastal phytoplankton blooms.


The San Diego Regional Climate Collaborative, a network of cities and agencies working to advance climate action in the San Diego region, has recently partnered with the Resilient Cities Catalysta nonprofit whose work is anchored in knowledge gained in the development of the urban resilience movement, bringing together a diverse set of skills across government, civil society and the private sector.

Partners worked specifically to develop and implement the “San Diego Coastal Exchange," an innovative virtual series of meetings, presentations and virtual work sessions with over 50 stakeholders engaged in coastal resilience from across the San Diego region. Through this partnership, video case studies of innovative coastal resilience solutions were developed, and highlight local projects here in the San Diego region, including the Cardiff Living Shoreline in the City of Encinitas.

University of San Diego Efforts and Projects

Knowing when it is safe to swim in our bays and beaches ensures the health and safety of San Diegans and tourists alike. Students at the University of San Diego (USD) are involved in intensive research on water quality, specifically in Mission Bay. Over the course of the last 10 years, students doing interdisciplinary research in classes have examined patterns typical of a Mediterranean-style estuary in Mission Bay. Water quality varies seasonally with rainfall and weather patterns. The eastern side of the Bay has, on average, worse water quality because it doesn’t mix with the ocean, but the western side of the Bay is less stagnant due to its proximity to the ocean. Therefore, it is generally safer to swim in the western side of the Bay. The goal in the next few years is to collect enough data to analyze long term trends as related to climate change and be able to predict further conditions of the Bay. They have also identified resources which educate and inform the public of the safety of swimming in Mission Bay. Their data and results are used to strengthen the Quality of Life Dashboard and to introduce initiatives for bettering water quality in San Diego

What Are We Measuring?

We measure the yearly trend in beach closures by tracking the total number of days San Diego beaches were closed or flagged with advisories due to health risks, measured in Beach Mile Days (BMD = number of days x length in miles of beach under advisory or closed). We also map out select beach advisories and closures along the San Diego coast and into Tijuana. Learn more about the data.