Live conditions in Great Pond, Biddeford Pool, Maine · UNE pond water-quality station
🕒 Latest reading: Wednesday, Oct 21 2026 at 06:10 PM. Tap ⓘ on any box to learn what it means.
This station is highlighted in orange. Hover over any other icon for its name, or click it to visit UNE's nearby buoys and stations.
Written automatically from the numbers — it changes as new data arrives.
Saturday, Aug 29, 2026. Total since records began here: 45.68 in (1160.3 mm). Last 24 hours: 0.00 in (0.0 mm).
Dissolved oxygen averaged 2.4 mg/L. It was below 2 mg/L (hypoxic — too little for most fish) 22% of the time and below 5 mg/L (stressful) 100% of the time. Still, warm, shallow ponds and marshes naturally run low on oxygen, especially at night and in late summer.
For comparison, ocean water is about 32–35 PSU and drinking water is about 0. Values in between mean a mix of fresh water (rain, streams, groundwater) and seawater.
From 2.7 ft (0.82 m) to 5.4 ft (1.65 m) relative to the sensor’s reference level. Highest on Sep 28, 2026.
Warmest Aug 11 at 5:25 AM; coldest Dec 29 at 5:30 PM.
A quick guide to each measurement on this page — no science degree needed.
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: typically 2.2 mg/L; 1.8 mg/L to 3.0 mg/L 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 10.1 PSU; 8.1 PSU to 12.4 PSU so far.
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; 39 °F to 77 °F so far.
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.
📍 Here: typically 4.0 ft; 2.7 ft to 5.4 ft so far.
What it is: Rain measured in a gauge, totalled for each hour and day.
Why it matters: Rain washes fresh water, sediment, nutrients and sometimes pollution off the land into ponds, marshes and the bay — watch salinity drop and turbidity rise after a big storm.
📏 1 inch = 25.4 mm. A summer thunderstorm can drop an inch in an hour; Maine averages about 45 inches a year.
📍 Here: 45.68 in (1160.3 mm) since Dec 2025.
All measurements on one shared timeline. Use the buttons to zoom to the last day, week or month, or drag across any panel. Click a name in the legend to hide or show it.
Each day's range (shaded) and average (line); bars are daily totals.
Averages, lows and highs for each month (newest first).
| Month | Days | Dissolved oxygen avg | low | high | Salinity avg | low | high | Water temperature avg | low | high | Water level avg | low | high | Rain total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Oct 2026 | 21/31 | 2.2 mg/L | 2.1 mg/L | 2.3 mg/L | 8.9 PSU | 8.2 PSU | 9.3 PSU | 15.9 °C | 13.5 °C | 18.2 °C | 1.30 m | 1.13 m | 1.51 m | 49.8 mm |
| Sep 2026 | 30/30 | 2.1 mg/L | 2.0 mg/L | 2.2 mg/L | 8.9 PSU | 8.3 PSU | 9.3 PSU | 20.2 °C | 16.7 °C | 22.7 °C | 1.18 m | 1.05 m | 1.65 m | 198.2 mm |
| Aug 2026 | 31/31 | 2.0 mg/L | 1.9 mg/L | 2.0 mg/L | 9.0 PSU | 8.1 PSU | 9.6 PSU | 23.6 °C | 22.4 °C | 25.0 °C | 1.22 m | 1.13 m | 1.33 m | 262.4 mm |
| Jul 2026 | 31/31 | 2.0 mg/L | 1.9 mg/L | 2.1 mg/L | 9.6 PSU | 9.1 PSU | 10.0 PSU | 23.2 °C | 21.9 °C | 24.3 °C | 1.35 m | 1.27 m | 1.43 m | 39.1 mm |
| Jun 2026 | 30/30 | 2.0 mg/L | 1.8 mg/L | 2.1 mg/L | 9.8 PSU | 9.3 PSU | 10.6 PSU | 19.6 °C | 15.3 °C | 22.1 °C | 1.41 m | 1.19 m | 1.52 m | 150.2 mm |
| May 2026 | 31/31 | 2.1 mg/L | 1.8 mg/L | 2.3 mg/L | 10.2 PSU | 9.6 PSU | 10.8 PSU | 14.6 °C | 12.1 °C | 17.6 °C | 1.31 m | 1.20 m | 1.46 m | 213.9 mm |
| Apr 2026 | 28/30 | 2.4 mg/L | 2.2 mg/L | 2.6 mg/L | 10.3 PSU | 9.9 PSU | 10.9 PSU | 9.2 °C | 6.9 °C | 12.7 °C | 1.25 m | 1.17 m | 1.38 m | 48.0 mm |
| Mar 2026 | 31/31 | 2.8 mg/L | 2.6 mg/L | 2.8 mg/L | 10.5 PSU | 10.1 PSU | 10.7 PSU | 4.9 °C | 3.8 °C | 6.9 °C | 1.14 m | 1.00 m | 1.31 m | 93.7 mm |
| Feb 2026 | 28/28 | 2.9 mg/L | 2.8 mg/L | 2.9 mg/L | 10.3 PSU | 10.3 PSU | 10.5 PSU | 4.3 °C | 3.9 °C | 5.0 °C | 1.01 m | 0.98 m | 1.09 m | 3.3 mm |
| Jan 2026 | 31/31 | 2.9 mg/L | 2.8 mg/L | 2.9 mg/L | 10.2 PSU | 9.9 PSU | 10.4 PSU | 5.4 °C | 4.5 °C | 6.5 °C | 0.93 m | 0.89 m | 1.03 m | 18.8 mm |
| Dec 2025 | 31/31 | 2.9 mg/L | 2.9 mg/L | 3.0 mg/L | 11.2 PSU | 10.2 PSU | 12.4 PSU | 4.4 °C | 3.7 °C | 5.4 °C | 0.84 m | 0.82 m | 0.91 m | 82.8 mm |
=IMPORTDATA("https://ekelting.github.io/UNE-Marine-Monitoring-Network/great-pond/data/daily.csv")