Clean waters

en español

This goal captures the degree to which local waters are unpolluted by human-made causes.

CORE DEFINITION

People value marine waters that are free of pollution and debris for aesthetic and health reasons.

Contamination of waters comes from oil spills, chemicals, eutrophication, algal blooms, disease pathogens (e.g., fecal coliform, viruses, and parasites from sewage outflow), floating trash, and mass kills of organisms due to pollution.

People are sensitive to these phenomena occurring in areas they access for recreation or other purposes as well as for simply knowing that clean waters exist.

In the global assessment, four measures of pollution are included in the clean waters goal: eutrophication (nutrients), chemicals, pathogens and marine debris. This group will assess what contamination applies to the Gulf, and will define the goal model accordingly.

The status of these components is typically the inverse of their intensity. This means that the high input results in low status score, and this goal scores highest when the contamination level is zero.

Key Questions

What is the ideal sustainable state of the clean waters goal?

  • How do we ideally measure the amount of contamination (or lack thereof) of waters in the Gulf of California?

  • How do we define the reference point, or the ideal amount of contamination? Is it zero, as it is in the global framework?

    • This may depend on what we want to include in the status of the goal. Does it include chemicals, pathogens, trash, nutrients? Are there any other types of contamination we want to add or remove?
    • The global OHI defined the contamination categories based on commonly considered contamination types in assessments of coastal clean waters (Borja et al. 2008), are there papers like this for the Gulf of California?

Goalkeeper Meetings

Meeting Access

Zoom Link: https://us06web.zoom.us/j/3255055973

Key Team Members
  • Alejandra Irasema Campos
  • David Alberto Salas de LeĂłn
  • Geovanni (Geo) Coredero Herrera
  • Jaqueline Garcia-Hernandez
  • Jorge Arriaga
  • JosĂ© Antonio Romero Gil
  • Miguel Betancourt
Meeting Schedule (Tuesday 10:00 AM - 11:00 AM PDT)
Meeting Date Focus
1 July 29, 2025 Group introductions, OHI platform overview, goal calculations
2 August 26, 2025 Model and reference point discussion
3 September 30, 2025 Model, reference point, and data sources
4 October 28, 2025 Preliminary results and pressure/resilience
5 November 18, 2025 Final analysis plan review
6 January 2026 (tentative) Tentative
Co-authorship Information

This project provides opportunities to collaborate with regional experts and contribute to Gulf of California OHI assessment. Participation will be acknowledged on the website and other products. Additional co-authorship opportunities may be available with extra commitment as outlined here.

Google Calendar

Add the shared calendar to your Google Calendar account using the provided link. It will appear under “Other calendars” and provide access to all scheduled meetings with updated Zoom links.

Please let us know if you have any questions. We look forward to working on this initiative with you!


Meeting Summaries

Thank you to everyone who joined our first Clean Waters (CW) Goalkeeper meeting!

This initial session introduced the OHI Gulf of California assessment and set the stage for how future meetings will unfold. It was a great start to our work together in defining what clean waters mean for the Gulf of California.

Meeting Recap

While this meeting mostly served as an introduction, we had a great discussion about possible components of the Clean Waters goal for the Gulf of California.

  • Ideally, we aim to identify the sources of contamination, though this may not always be feasible with available data.
  • Some contaminants dissolve in freshwater but condensate upon entering seawater, causing them to adhere to marine sediments.
  • JosĂ© Antonio shared insights from a paper he’s working on with Ben, which could help us quantify nitrogen (N) and phosphorus (P) in coastal regions around the Gulf.
  • Miguel noted the existence of a seafood alert system: when harmful algal blooms or poor water quality are detected, advisories are issued against eating shellfish farmed in affected areas. [From COFEPRIS?]
Key Contaminant Categories Discussed:
  • Nutrients
    • Turbidity (suspended sediments)
    • Nitrogen
    • Phosphorus
    • Organic matter (BOD/COD)
  • Chemicals
    • Hydrocarbons from ships (oil/diesel)
    • Heavy metals
    • Pesticides / Persistent Organic Pollutants (POPs)
    • Microplastics
    • Human-caused accidents (e.g., acid spills, harmful algal blooms)
    • Pharmaceuticals
  • Pathogens
    • Bacterial: fecal coliforms, E. coli
    • Vibrio species
    • Viral pathogens
  • Marine Debris
    • Plastic pollution
    • Abandoned fishing gear (nets, lines)
    • Microplastics (also listed under Chemicals)

⚠️ Note: Some contaminants, like microplastics, fall into multiple categories, such as both Chemicals and Marine Debris. If you think it should be in one category versus another, please note this on the CW Model Notes document.

Next Steps
    • Add any additional contaminants, sources, or relevant datasets.
    • Presence, frequency, and sources of these contaminants
    • Potential reference points or thresholds

In our next meeting, we’ll continue our discussion of contaminants that should be considered in this goal.

We’ll also start to define the reference point for this goal — our vision of what ideal, clean waters look like. In assessment terms, this is the “100” score — our A+ target!

Thank you to everyone who joined our second Clean Waters (CW) Goalkeeper meeting!

This session built upon our introduction in Meeting #1. We began to define what clean waters mean in an ideal world for the Gulf of California, and brainstormed possible indicators to measure progress toward this goal.

Meeting Recap

We reviewed Meeting #1 takeaways:

  • The OHI GoCA project is part of a three-legged stool framework: Index, Investment, Action.
  • The Clean Waters goal captures the degree to which local waters are unpolluted by human-made causes, with implications for ecosystem health, human recreation, and food safety.
  • Contamination categories include: Eutrophication (nutrients), Chemicals, Pathogens, and Marine Debris.

We then focused on two key questions:

  1. What is the ideal state of Clean Waters in the Gulf of California?
  2. What indicators could capture this state in practice?
The Ideal State of Clean Waters

In a perfect world, clean waters in the Gulf would mean:

  • No contamination of marine and coastal waters
  • Safe swimming & recreation (no beach closures)
  • Safe seafood (low heavy metal content)
  • No spills or illegal dumping
  • Healthy ecosystems: fish biomass, species richness, trophic balance, and habitat recovery (will be covered in the Biodiversity goal)
Possible Indicators Mentioned

(not all are formal indicators yet – these are ideas to refine further)

Biodiversity & Ecological Function

  • Fish biomass
  • Species richness
  • Trophic balance
  • Habitat recovery
  • Recovery of endangered species

Pollution & Human Health

  • The number of oil spills/year
  • Area (km²) of surface affected by spills
  • Volume of oil spilled (L/km²)
  • Wastewater treatment efficiency (% treated; goal = 100%)
  • Frequency of beach closures

Waste Management & Plastics

  • Compliance with “clean fleet” policies
  • Tour ships not dumping waste
  • Ban on single-use plastics
  • Circular economy initiatives (green jobs, regenerative approaches)

Chemical & Mining Impacts

  • Hydrocarbon inputs from small-scale fisheries & industry
  • Bioindicator monitoring (bird eggs, mussel watch programs)
  • Reduced nutrient inputs from aquaculture/fish waste
  • Ban on artisanal mercury mining; best practices for commercial mining

Harmful Algal Blooms (HABs)

  • Monitoring via satellite (N, chlorophyll, sediments) + in situ validation
  • Predictive hotspot alerts

Nature-Based Solutions (NBS) and other frameworks

  • Wetland water treatment
  • Mangrove health preserved
  • Agriculture runoff managed with NBS
  • Source-to-Sea (S2S) framework (Mathews et al., 2019)
Relevant resources

  • Potential for “clean fleet policies”: EPA: Collaboration with Mexico to Reduce Emissions from Ships

  • Best available mining practices: Amendments to Mexican Mining and Environmental Laws: a Comprehensive Overview (2023)

    “Requirement for maintaining a Restoration, Closure, and Post-closure Program: The New Bill mandates that mining concession holders submit to the Ministry of Environment and Natural Resources a Restoration, Closure, and Post-closure Program to ensure compliance with environmental regulations upon the termination of a mining concession for any reason. This program includes plans for site remediation, waste management, and environmental monitoring during and after the closure of mining operations.”

  • PROFEPA: Federal Attorney’s Office for Environmental Protection

    “What do we do?”

    “Monitor and evaluate compliance with legal provisions applicable to the restoration, preservation, and protection of natural resources through visits and inspections, addressing public complaints, and promoting social participation in matters of environmental protection and defense.”

  • Source-to-Sea (S2S) framework: (Mathews et al., 2019)
    A guide for practitioners to connect freshwater and marine pollution management across the full land-to-sea continuum.

    “The source-to-sea concept defines key flows found within a source-to-sea system;describes six steps to guide analysis and planning; and presents a framework for elaborating a theory of change; all with an aim of designing initiatives that support healthy ecosystems and sustainable green and blue economies.”

  • Páez-Osuna et al. (2017): Environmental status of the Gulf of California: A pollution review

    Identifies pollution from economic activities as one of the four major environmental problems in the region (focus of CW goal).

    Key Contamination Findings (from literature review):

    • Nutrients & Eutrophication
      • Reported mainly in estuaries and lagoons of the north and central Gulf, especially those influenced by aquaculture (shrimp farms) and agriculture runoff.
      • Indicators: dissolved oxygen (hypoxia), chlorophyll-a, and nutrient concentrations (N, P).
    • Harmful Algal Blooms (HABs)
      • More frequent and intense in the southern Gulf and central coastal lagoons, with records of sanitary closures and red tide events.
      • Indicators: phytoplankton cell counts, chlorophyll-a, closure events.
    • Chemicals
      • Metals & metalloids: higher concentrations in northern Gulf estuaries near mining and industrial activities.
      • Pesticides & POPs: concentrated in central and southern Gulf, especially in fishing grounds and near agriculture zones.
      • Hydrocarbons (oil, diesel): localized near ports, coastal urban centers, and oil transport routes (mainly central/southern Gulf).
    • Pathogens
      • Fecal contamination reported in coastal waters near urban centers (ex: Mazatlán, Guaymas, La Paz).
    • Marine Debris
      • Macro- and microplastics recorded in surface waters of the central Gulf and in sediments/organisms throughout the Gulf, with hotspots near urbanized coasts and fishing activity zones.
Next Steps

In our next meeting, we will:

  • Finalize our vision of the ideal state
  • Begin to match indicators with real world datasets

Please keep brainstorming and contributing ideas, as your input is key to shaping how we measure clean waters in the Gulf of California!

During our group activity on the Clean Waters goal, we focused on identifying key contaminants, possible data sources, and technical reference points to evaluate the extent to which local waters remain free from human-caused pollution.

Meeting #3 Activity

Throughout the discussion, we organized our work around four main categories of contaminants: pathogens, nutrients (eutrophication), chemicals, and marine debris. For each category, we reviewed existing data sources, their limitations, and possible indicators for evaluation.

  • Pathogens:
    We considered data from CONAGUA (wastewater treatment plant inventories), the Clean Beaches Program from COFEPRIS, and international guidelines (WHO). The group highlighted the uncertainty of wastewater treatment efficiency in rural areas and the reliability of official program data compared with scientific literature. Bacterial indicators such as E. coli and enterococci, as well as viruses introduced from human sewage, were discussed as indicators.

  • Nutrients (Eutrophication):
    Possible data sources included nutrient output models from aquaculture and agriculture, records of sanitary closures and red tide events, and the HAEDAT database of harmful algal blooms (HABs). The group emphasized the importance of nature-based solutions for nutrient management and combining satellite monitoring with in-situ measurements to better predict and track harmful algal blooms (HABs).

    As of now, the OHI Core Team feels that tracking HAB events in the GoC is the best indicator. This is because nutrient inputs in the marine system are not necessarily bad unless they cause a HAB that affects both the species there, and humans. Therefore, it would make more sense to track HABs, rather than try to estimate how much nutrient pollution becomes an issue.

  • Chemicals:
    Discussions focused on pesticides, heavy metals, and hydrocarbons. Sources included SEMARNAT and mining industry databases, as well as scientific studies using bioindicators (bivalves, fish). We noted the importance of evaluating mining practices, tracking oil spills, and assessing compliance with “clean fleet” fuel and waste management policies.

    SEMARNAT has the most promising data for heavy metals and hydrocarbons in coastal areas, as they have the number of contaminated sites by entity, municipality, year (2015-2025), and type/name of contaminant; Hazardous waste generation estimates by types of waste, from 2017 - 2025 by state and by municipio; and a list of contaminated and remediated sites with their exact location and the year they were identified/remediated.

  • Marine Debris:
    The group examined both micro- and macroplastics, citing recent studies on fish and sea lions, along with the National Inventory of Plastic Pollution Sources. Possible reference points could be improving waste management practices in coastal communities and considering policies on single-use plastics.

Overall, the group agreed that the main challenge is identifying/harmonizing diverse data sources and defining clear technical reference points to translate this information into meaningful indicators for the Clean Waters goal in the Gulf of California.

NEXT STEPS:

  • Miguel will reach out to Dr. Paez-Osuna for data used in the Environmental Status of the Gulf of California paper from 2017.
  • We will continue to evaluate the usability of data (Clean beach program report (programa playas limpias) / COFEPRIS / CONAGUA)
  • Jaqueline will advise us on inconsistencies in the Playas Limpias program.

Thank you all for your thoughtful input and time! We are so appreciative of the collective effort that will be necessary to obtain robust CW scores.

In this fourth meeting of the Clean Waters working group, we reviewed the selected indicators, potential reference points, and data sources for each component of the goal. We also discussed methodological adjustments and included a new component (sedimentation).

Meeting #4 Presentation

The OHI Core Team presented progress on structuring pollution indicators and identifying usable data sources. Discussion focused on how to interpret, scale, and combine different types of data into a single, meaningful score.

Summary of Discussion

  • Overall structure of the goal:
    The group reaffirmed that the Clean Waters goal aims to capture the extent to which local waters remain unpolluted by human activities. The main components continue to be eutrophication, pathogens, chemicals, and marine debris, with the new and tentative addition of sedimentation as a fifth, separate component.

  • Methodology and aggregation:
    The goalkeeper team reviewed how each indicator will be scaled from 0 - 100 and then combined within each component, which will then be combined into an overall Clean Waters score.
    Miguel suggested using example or mock data to visualize how indicator scores behave under different scenarios before deciding on an aggregation method (geometric or weighted mean).
    The OHI Core Team will prep to discuss this in detail in the next meeting on November 18th.

Reviewed Components

1. Eutrophication

  • The group agreed to focus indicators on observable negative outcomes, rather than absolute nutrient levels (N and P).
  • It was validated that harmful algal bloom (HAB) occurrence should be the main indicator, using data from the HAEDAT database (1979–2023), with an emphasis on identifying regional trends and potential causes.
  • Jacqueline and Miguel recommended comparing each region with itself over time, since natural conditions vary greatly.
  • Melanie suggested weighting events based on their ecological or human impact, since not all HABs cause the same level of stress.
  • The inclusion of chlorophyll-a satellite data (Copernicus Marine) was supported as an additional indicator to detect increases in algal biomass compared to historical concentrations.

2. Sedimentation (potential new component)

  • The group discussed separating sedimentation and turbidity into a new component, as they do not always coincide with eutrophication.
  • Miguel linked sedimentation to erosion and deforestation in upper watersheds, while Jacqueline noted its natural influence in the Upper Gulf (Colorado River discharges and strong tidal mixing).
  • It was agreed that potential indicators could include Secchi depth (Copernicus Marine Service / CONABIO) or total suspended solids (CONAGUA RENAMECA), analyzed as deviations from historical averages.

3. Pathogens

  • Two main indicators were confirmed:

    1. Beach suitability (APTA/no APTA) – based on enterococcus levels from the Playas Limpias program (COFEPRIS).

      • Access to historical data remains a challenge, and requests have been submitted through the National Transparency Platform.
      • Melanie suggested that, because this is direct human contamination, the reference point could simply be “zero contamination”, without requiring long-term historical series.

    2. Sewage inputs – modeled using coastal population data, sanitation access, and wastewater treatment efficiency.

      • The OHI Core Team will continue to search INEGI and CONAGUA for data on who has access to sanitation facilities, how the sanitation systems in MĂ©xico work, and how efficient they are in removing pathogens.

4. Chemicals

  • The group reviewed data from SEMARNAT on hazardous waste sites and chemical pollutants, including pesticides, hydrocarbons, and heavy metals.
  • The most promising dataset is: Contaminated and remediated sites (by state, municipality, year, remediation program, waste type, etc).
  • These data provide the opportunity to evaluate both point-source pollution and remediation efforts, helping to capture the balance between contamination and recovery.
  • Jacqueline suggested that indicators should not only record whether programs or facilities exist, but also evaluate their operational efficiency or level of compliance.
  • Miguel emphasized that this component could include a resilience-type indicator, such as the number or effectiveness of programs to eliminate point sources (e.g., clean fleet policies, industrial wastewater controls).
  • Indicators of pesticides, pharmaceuticals, and vessel pollution in the GoC do not currently have data source identified for them. Everyone will continue to research these topics.

5. Marine Debris

  • The group discussed both macroplastics and microplastics.
  • Potential indicators include:
    • Management condition of coastal waste sites from SEMARNAT – assuming better management reduces plastic leakage into the ocean.
    • Policies or bans related to single-use plastics, as suggested by Miguel, in which these have a big impact on the plastic pollution that makes it ot the ocean.
    • Organized beach cleanups, as a measure of community action and mitigation.
  • It was agreed that this component should combine management-based indicators (preventive) and removal-based indicators (reactive) to better reflect progress toward cleaner coastal waters.

Next Steps

  • The OHI team will present preliminary indicator scores and possibly some mock combinations at the next meeting to illustrate how indicators and weights can behave in combination.
  • Sophia will circulate updated summary statistics of HAB events filtered to include only Gulf of California municipalities.
  • The team will continue evaluating the inclusion of sedimentation as a fifth component, and follow up on access to Playa Limpias data through transparency requests.

Many thanks to everyone for your thoughtful technical contributions and the collaborative effort to strengthen the Clean Waters goal methodology. Please continue to stay in touch if you have any ideas!

Thank you to everyone who joined Clean Waters Meeting #5!
This session focused primarily on the Expert Group Activity to rank chemical pollution indicators by region. We also briefly reviewed the updated slides, which provide full details for each Clean Waters component.

If you could not attend, please review the slides here:
Meeting #5 Slides

Meeting Recap

1. Expert Activity: Ranking Chemical Indicators (Main Discussion)

Together, we walked through each OHI region and ranked the chemical indicators from 1 (most relevant) to 5 (least relevant) based on your expert judgment of local conditions.

The indicators evaluated were:

  • Hazardous waste point sources (such as hydrocarbon sites, industrial waste, geothermal metals)
  • Pesticide pollution (FAOSTAT-based estimates + regional agricultural patterns)
  • Pharmaceutical pollution (untreated discharges, aquaculture, livestock)
  • Impervious surfaces (urban runoff potential)
  • Vessel pollution (hydrocarbon loads from fishing + commercial fleets)

Key takeaways from the ranking activity:

  • Regions with mining, geothermal activity, or industrial facilities ranked hazardous waste as their highest impact pollutant.
  • Regions with intensive agriculture or large valleys ranked pesticide pollution as their most relevant indicator.
  • Regions with aquaculture clusters (especially shrimp farming) ranked pharmaceutical contamination among their top concerns.
  • Regions with major fishing ports consistently ranked vessel pollution as highly impactful.
  • Most regions ranked impervious surfaces as lowest impact, given limited rainfall and a lack of paved roads in rural areas.

These rankings will help the OHI Core Team prioritize and weight chemical pollution indicators for the Clean Waters goal.

2. Overview of Other Components (Not Discussed Live)

Although we did not have time to review the other components during the meeting, the slides summarize current progress for all sections of Clean Waters:

Eutrophication

  • Indicators include chlorophyll-a pressure using Copernicus Marine Service. Mel made slides on the current methodology; please ask us any questions you might have on this.
  • We will not be using HAB occurrences from HAEDAT data anymore due to the stochastic nature of the data and the fact that it is likely underreported. Additionally, we do not have the spatial extent of each bloom.

Sedimentation

  • The proposed new component from last meeting will be based on secchi depth from SIMAR/CONABIO and Copernicus.
  • Tracks long-term changes in water clarity and possible sediment inputs.
  • Similar methodology to Chl-a.

Pathogens

  • Beach suitability (APTA/no APTA) based on enterococcus levels remain a core indicator.
  • Sanitation access and WWTP efficiency will be used to estimate pathogen loads entering coastal waters.
  • Additional transparency requests are underway to obtain updated Playas Limpias data from COFEPRIS.

Marine Debris

  • Indicators include:
    • Coastal waste site management condition (SEMARNAT)
    • Beach cleanups (Ama tu Playa 2025-2030 strategy)
  • Requests have been submitted for both datasets in tabular or shapefile format.

Next Steps

  • The OHI Team will assemble preliminary scores for each indicator and share mock combinations to compare aggregation approaches (geometric vs. arithmetic).
  • Please continue contributing ideas for each component, especially where data may still be missing.
  • The next meeting (January) will begin reviewing current status scores and models.

Thank you all for your valuable regional expertise and contributions to strengthening the Clean Waters goal!

Stay tuned for Meeting #6 resources.


Additional Insights & Examples

These are some of the points discussed by the Expert Working Group (EWG).

Contamination Sources and Assessment Challenges

Multiple Non-Point Sources
  • Sardine/canning industry
  • Shipping traffic
  • Agricultural and aquaculture operations
  • Urban discharges
  • Fish waste
Monitoring Data Gaps
  • More comprehensive data available for Sinaloa and Sonora coasts
  • Limited information for La Paz and Baja California regions
  • Sediment analysis often overlooked despite significant ecosystem impacts
Weather and Climate Impacts
  • Rainfall increases trash accumulation and degrades water quality
  • Hurricanes and storms create additional ecosystem pressure
  • Intermittent river systems cause sudden freshwater inputs that marine ecosystems cannot handle

Ecosystem and Community Impacts

Invasive Species Effects
  • Cattails provide natural filtration but face threats from invasive Placostomos
  • Non-native species have fundamentally altered community structures
  • Root system damage impacts native fish populations like tilapia
Aquaculture Concerns
  • Shrimp farms generate nutrient runoff affecting other fisheries
  • Eutrophication problems documented by local fishermen
  • Pathogen issues primarily affect swimming areas
Unique Regional Challenges
  • Dependence on ocean-derived freshwater for drinking water
  • Questions about integrating water quality standards into ocean health goals

Monitoring and Assessment Approaches

Community-Based Efforts
  • Organized trash pickups throughout the Gulf
  • Volunteer diving cleanup programs
  • Local community engagement in monitoring efforts
Scientific Assessment Tools
  • TRIX Index: Combines chlorophyll-a and nutrient data to classify water as eutrophic or oligotrophic
  • Satellite monitoring: Provides temporal analysis capabilities
  • Biological indicators: Cannonball jellyfish appearance signals hypoxic conditions and dead zones
Case Study: Santa Maria Lagoon
  • 10-year TRIX analysis revealed dramatic ecosystem shift
  • System changed from nutrient sink to nutrient exporter
  • Demonstrates rapid ecological changes in regional waters

Emerging Pollution Concerns

Noise and Light Pollution
  • Ship noise impacts whale communication and behavior
  • Industrial development pressures highlighted by “Whales or Gas?” campaign
  • Questions about classifying noise/light as water quality threats
Synergistic Effects
  • Nutrients and chemicals interact to create algal blooms
  • Need for multiplier effects in assessment methodologies
  • Complex interactions require integrated pollution assessment approaches


Contact via email:

OHI Core Analytical Team Clean Waters Goalkeeper Group