What the water is doing off Ferry Beach in Saco Bay, Maine · BlueSonde BB1.47
🕒 Latest reading: Wednesday, Oct 21 2026 at 07:01 PM. How salty is it? The salinity scale (fresh water from rain, streams or rivers lowers it):
This buoy is highlighted in orange. The others are UNE's nearby wave buoys (yellow) and water-quality buoys (orange floats) — hover over one for its name, click to visit its page.
Predicted by NOAA for Camp Ellis, Saco River entrance (station 8418606). Heights are above average low tide (MLLW).
Big-picture numbers from every reading so far.
Written automatically from the numbers — it changes as new data arrives.
Averaged over each tide cycle, salinity only shifts by 0.6 PSU between high and low water. Fresh water mostly reaches the buoy after heavy rain — watch for the dips in the salinity chart.
Recorded Sep 28 at 8:14 AM. Typical salinity is 29.1 PSU (full seawater is about 32–35). Sharp dips usually follow heavy rain, when streams and runoff carry fresh water out to the buoy.
Average water temperature this past week was 12.5 °C (55 °F), versus 13.0 °C (55 °F) the week before. Warmest so far: 18.1 °C on Sep 18; coldest 10.6 °C on Oct 18.
Dissolved oxygen averaged 8.7 mg/L and never went below 6.7 mg/L (lowest Oct 9 at 3:46 AM). Below 5 mg/L many fish start to feel stressed; below 2 mg/L (hypoxia) most can't stay.
Algae add oxygen in daylight and everything uses it up at night. On a typical day oxygen saturation swings by about 12 percentage points, peaking around 4 PM.
Tryptophan-like fluorescence glows brighter when there is more fresh organic matter in the water, including wastewater and runoff, so it is used as an early warning for contamination. This sensor reads below zero, so treat the numbers as relative: what matters is a rise above its usual level. Highest reading: -22 ppb on Oct 8 at 10:46 PM.
Turbidity measures how cloudy the water is. Under ~5 NTU is clear coastal water; spikes (highest Sep 14 at 7:16 AM) come from storms stirring up sediment, runoff after rain, or now and then something drifting past the sensor.
A quick guide to each measurement on this page — no science degree needed.
What it is: How warm or cold the water is, measured by a sensor just below the surface.
Why it matters: Temperature controls almost everything in the water: how much oxygen it can hold, how fast algae grow, which fish and shellfish are comfortable, and when lobsters and other animals move or molt.
📏 Gulf of Maine coastal water runs roughly 38–45 °F (3–7 °C) in late winter and 60–68 °F (15–20 °C) in late summer. Shallow ponds and marshes swing much more, warming fast on sunny days.
📍 Here: typically 56 °F (13.2 °C); 51–65 °F so far.
What it is: The amount of dissolved salt in the water, in PSU (practical salinity units) — about the same as grams of salt per kilogram of water.
Why it matters: Saltiness tells you where the water came from. Fresh water from rain, streams, rivers or groundwater lowers it; ocean water raises it. Many plants and animals can only live within a certain salt range.
📏 Drinking water ≈ 0. Brackish (mixed) water ≈ 5–18. Open Gulf of Maine ≈ 31–33. Sudden drops usually follow heavy rain.
📍 Here: typically 29.1 PSU; lowest so far 21.0, highest 29.8.
What it is: Oxygen gas dissolved in the water — the oxygen that fish, crabs, clams and worms breathe through their gills or skin. Shown in mg/L (milligrams per litre), and sometimes as % saturation: 100% means the water holds as much oxygen as it naturally can at that temperature and saltiness.
Why it matters: Low oxygen stresses or kills marine life. It drops when water is warm, still, or full of decaying plant material, and it swings up and down every day because algae make oxygen in sunlight and everything uses it up at night.
📏 Above 5 mg/L: healthy. 2–5 mg/L: stressful for many species. Below 2 mg/L: hypoxic — most fish leave or die. Saturation above 100% means algae are photosynthesising hard.
📍 Here: averages 8.7 mg/L; lowest so far 6.7 mg/L.
What it is: Tryptophan is one of the building blocks of proteins. It glows under ultraviolet light, and the sensor measures that glow. It is abundant in sewage, septic-system leaks, animal waste and freshly decaying plant and animal matter.
Why it matters: A rise in tryptophan signal is an early warning that wastewater or other organic pollution may be reaching the water — often before bacteria tests come back from a lab. It helps decide when to check shellfish beds or swimming beaches.
📏 Watch for changes, not the number itself: these sensors are not calibrated to an absolute scale (they can even read below zero). A sharp rise above the usual level, especially after rain, is the thing to notice.
📍 Here: usual level about -68 ppb on this sensor — look for rises above that.
What it is: How cloudy the water is, from mud, sand, algae or other particles. The sensor measures how much light scatters off them, in NTU (nephelometric turbidity units).
Why it matters: Cloudy water blocks sunlight from reaching seagrass and seaweed, can clog the gills of shellfish, and often carries pollutants stirred up by storms or washed off the land.
📏 Under ~5 NTU: clear. 5–20: a little cloudy. 20–100: murky (storm waves, runoff). Single sharp spikes are often something drifting past the sensor.
📍 Here: typically 0.2 NTU.
What it is: How easily electricity passes through the water. Dissolved salt carries the current, so conductivity is how the sensor measures salinity. "Specific" conductivity is adjusted to 25 °C so readings can be compared.
Why it matters: It is the raw measurement behind the salinity number, and a quick check that the sensor is underwater — it drops to about zero in air.
📏 Seawater ≈ 50,000 µS/cm (50 mS/cm). Fresh river water ≈ 50–500 µS/cm.
📍 Here: typically 45.1 mS/cm.
What it is: The height of the water surface. Along the Maine coast the sea rises and falls about 9 feet twice a day (every ~12 h 25 min), pulled by the Moon and Sun.
Why it matters: The tide moves water — and everything in it — back and forth past a sensor, so many readings change with the tide. In marshes and ponds, water level shows how often the tide floods in and how high storms push it.
📏 Heights on tide charts are measured above average low tide (MLLW). Storms and strong onshore winds can push water higher than predicted.
All the measurements on one shared timeline, with the tide on top. Use the buttons to zoom to the last day, week or month, or drag across any panel. Dashed lines on the oxygen panel mark the 5 mg/L stress and 2 mg/L hypoxia levels.
Each line is the typical value (the median) across every tide so far, lined up by hours before (−) and after (+) high tide; the shaded band holds the middle half of readings. The rising tide brings in ocean water; the falling tide carries water from closer to shore back past the buoy.
High-tide times from NOAA predictions for station 8418606 (Camp Ellis, Saco River entrance).
The typical value (median) for each hour of the day, with the middle half of readings shaded. Algae make oxygen in sunlight and everything uses it up overnight; the water warms through the afternoon; and chlorophyll readings dip at midday when bright sun makes the algae glow less.
Each square is one day. Pick what to colour by. Blank squares = no data.
Averages, lows and highs for each month (newest first).
| Month | Days | Temp avg | Temp low | Temp high | Salinity avg | Salinity low | Oxygen avg (mg/L) | Oxygen low | Tryptophan avg (ppb) | Trp. high | Turbidity avg (NTU) | Turb. high |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Oct 2026 | 21/31 | 55.7 °F | 51.1 °F | 61.6 °F | 29.2 | 22.7 | 8.5 | 6.7 | -72 | -22 | 0.7 | 8 |
| Sep 2026 | 19/30 | 60.6 °F | 58.4 °F | 64.5 °F | 28.3 | 21.0 | 9.3 | 8.1 | -50 | -35 | 1.3 | 18 |
Power and conditions inside the hull, hourly. The voltage channel drops to 0 every night and climbs with the sun, so it looks like solar-charge input. Humidity creeping upward can mean moisture is getting in.
=IMPORTDATA("https://ekelting.github.io/UNE-Marine-Monitoring-Network/ferry-beach/data/daily.csv")