About Tarline

How Scoring Works

Tarline scores every report with a two-factor model (scoring engine v2): how much tar degrades the beach visit, and how much the evidence says to be cautious about. The two are kept separate on purpose — a field of bone-dry, weathered tar balls is a big nuisance but a small health signal; a thin sheen in the water is barely visible but the single biggest caution flag Tarline tracks. Coverage class, tar-ball size/consistency, and oil form still borrow their vocabulary from NOAA's Shoreline Cleanup Assessment Technique (SCAT), so a Tarline report and a professional shoreline survey describe tar the same way.

Score Scale

The same 10-to-1 range as a single strip: flag-band colors underneath, the calibration anchors marked on top.

Score Ladder

Where a report lands on the 10-to-1 scale, anchored to the owner's calibration points (bold) and the public flag-band boundaries (thin dividers).

1. 10.0 No tar Clean sand, clear water -- nothing to penalize.
2. 8.1 Hard, sporadic tar balls Weathered tar balls scattered underfoot, water clean. Owner anchor -- “hard, sporadic tar balls ≈ 8, easy to enjoy the beach.”
3. 7.0 Green / yellow line Below 7, Tarline starts calling the water “posted.”
4. 6.2 Soft, sticky tar, widespread Sticks to your feet across most of the beach, water still clean. Owner anchor -- “softer, widespread ≈ 6–7, still a normal beach day.”
5. 4.4 Sheen alone in the water Sand looks fine; a sheen on the water pulls the score down on its own -- toxicity and experience are separate axes.
6. 4.0 Yellow / red line Nuisance is no longer the whole story -- toxicity signal is climbing.
7. 2.5 Red / black line Tarline treats the water as effectively closed at this point.
8. 1.3 Widespread sheen on sand and in the water Fresh, greasy oiling on the beach and a sheen with a petroleum smell in the water. Owner anchor -- “widespread oily sheen on the beach and in the water ≈ 1–3.”

Experience vs. Toxicity

Because the two penalties are independent axes, the same tar can land in very different places depending on which one it drives. Widespread hard tar (top-right) is a high-nuisance, low-toxicity read; a lone sheen in the water (bottom-left) is the opposite — barely a nuisance, but the highest-toxicity signal Tarline has.

Score Matrix (Experience × Toxicity)

The formula itself, gridded: every whole-number Experience/Toxicity combination and the score it produces (10 − E − T, clamped 1–10), colored by flag band. Real reports rarely land on every cell — each sand form has its own achievable ceiling on E and T — but the arithmetic is identical everywhere in the grid.

Experience Penalty Factors (E, 0–4)

Nuisance points, added together and capped at 4.

Toxicity Signal Factors (T, 0–5)

Caution points, added together and capped at 5. Water-column signs are weighted well above everything else — see the evidence for why.

Worked Examples

The three owner-calibrated anchors, with the full arithmetic. Sand and water are scored separately, then the lower (worse) of the two wins — the same "min-ish blend" the beach-level aggregate has always used.

The Evidence Behind the Score

Full sourcing, confidence ratings, and open questions live in Tarline's internal evidence brief; this is the summary. Three findings from the toxicology literature shape every constant above:

• Weathered tar is a low-acute-risk nuisance, not harmless. NOAA's public guidance on tar balls is direct: weathered tar is "hard and crusty on the outside and soft and gooey on the inside," and "occasional brief contact with a small amount of oil, while not recommended, will do no harm" for most people (some get rashes). That's the evidence basis for scoring hard/dry tar as mostly a nuisance — NOAA Office of Response & Restoration — Tarballs.
• The hazardous fractions weather out first. Volatile aromatics (BTEX, including benzene — a known human carcinogen, abundant in fresh crude but largely gone from weathered tar) evaporate within hours to days; the residue left behind is dominated by heavier, less bioavailable compounds. Total petroleum hydrocarbons (TPH) can still affect the central nervous system, skin, and lungs on contact or inhalation, and PAHs — the persistent fraction that dominates weathered tar — are carcinogens with hazard well established but human dose-response from casual skin contact not well quantified. Sources: ATSDR ToxFAQs for Total Petroleum Hydrocarbons, Polycyclic Aromatic Hydrocarbons, and Benzene.
• Water contact opens routes a dry tar ball doesn't have. Oil or sheen in swimmable water adds incidental ingestion and whole-body dermal contact — routes a beach tar ball sitting on dry sand simply doesn't have. Standard spill-response practice converges on the same precaution regardless of a fixed numeric threshold: avoid contact, and don't enter water where oil or sheen is visible. That's why the Toxicity Signal table above weights water signs so far above everything else.

No Statewide Petroleum Standard

California's only standing beach-posting law, AB411, covers bacterial water quality (fecal indicator bacteria) — there is no equivalent standard for petroleum. Beach closures during an active spill are called case-by-case by local health officers and Unified Command based on visible oiling, not a fixed public index. Outside of a declared spill, oil and tar simply go unposted, whatever the sand and water look like. That gap is exactly what Tarline's score exists to fill — not a legal advisory, but a continuously updated, sourced read on conditions AB411 was never built to cover.

A Brief History

Tar on Santa Barbara's beaches is partly a story of geology and partly a story of industry — the two are hard to fully untangle, which is exactly why records matter. This is the short version; read the full story for the long one.

1. 1896 Summerland becomes the site of the world's first offshore oil wells, drilled from piers reaching into the surf. Roughly 400 wells are eventually sunk; several, including the Becker well, are still known to leak today.
2. 1928 Barnsdall Oil and Rio Grande Oil strike oil at Ellwood in July, opening one of the richest fields on the California coast.
3. 1942 On the night of February 23, the Japanese submarine I-17 surfaces off Ellwood and shells the oil field — one of the only attacks on the American mainland during World War II.
4. 1969 On January 28, Union Oil's Platform A blows out, releasing an estimated 3 million gallons of crude into the Santa Barbara Channel — a spill that galvanized the modern environmental movement.
5. 2015 A corroded pipeline operated by Plains All American ruptures near Refugio State Beach on May 19, with roughly 100,000+ gallons reaching the ocean (estimates of the total spilled vary by source).
6. 2026 In July, elevated tar reports along the South Coast — concentrated around Carpinteria — prompt a public advisory. The source is unconfirmed as of publication; natural seepage is suspected but not established.

Where the Data Comes From

Tarline layers live feeds, static reference layers, and archival datasets, each credited and linked back to its publisher below.

For Researchers

Research groups are invite-only cohorts whose reports carry a provenance tag, so academic and agency partners can separate their own field crews' observations from the general public feed. The research portal exports the underlying dataset as CSV, GeoJSON, or JSON, filterable by cohort and quality grade, in a schema compatible with SCAT field records.

Every report carries a quality grade -- A for a verified research-group member, B for a signed-in user, C for anonymous -- which sets how heavily it's weighted into a beach's score (see the recency/trust weight above). Attaching at least one photo upgrades an anonymous (C) report to B, the same trust bump as signing in, since a photo is stronger evidence than a bare claim; B and A reports are unaffected. Exports include a photo_count column alongside the (photo-adjusted) qualityGrade so researchers can see both.

Further Reading

Credits & Licenses

Data: NOAA (NDBC, CO-OPS, NWS, OR&R, OSPO) · Scripps CDIP (DOI 10.18437/C7WC72) · USGS · USCG National Response Center · CDFW-OSPR · CalGEM · BOEM · California Coastal Commission · CA Water Board (ODC-By).

Maps: © OpenStreetMap contributors (ODbL), served via OpenFreeMap; terrain from AWS Open Data. Typeface: Roboto, self-hosted — no external font requests.

Tarline is in beta. This demo deployment shows the SAMPLE DATA badge in the header and footer; going forward, report data is real user submissions.