Public water reading
Lago de Chapala
Ajijic, Jalisco, Mexico · 20.2328, -103.2799 · 26,376 hectares of water
Workable water, carrying more than it should.
Lago de Chapala is workable water that is turning — the plan must come before the capital, scoring 54 out of 100. Something discharges to, or works beside, this water. The rain that feeds this water has been falling for twenty years.
Five readings
12 of 12 sources answered · 100% of pillar weight read
The water
What this body is, how it reads from orbit, whether it stays, and the basin it sits in.
The body
1 mapped inflow
Clarity · from orbit
One Sentinel-2 pass, 2026-08-26, 13% cloud in the scene. Indices, not concentrations: a bottle to a lab decides; this says where to dip it.
Permanence · 1984–2021
The basin
The edge
What the shore is made of, what lives here, what presses on the water, and what the climate does to it.
The shore · 300 m ring
- Tree cover 35%
- Built-up 22%
- Cropland 20%
- Grassland 16%
- Shrubland 6%
- Bare / sparse 1%
Life
Most recorded: Pelecanus erythrorhynchos · Nycticorax nycticorax · Fulica americana · Ardea alba
Pressure
industrial land on the shore
Climate · to 2050
Expect is the honest verb: the middle of a range of futures, one scenario, not a certainty. Warmer air means warmer, more stratified water and more evaporation.
Hazard screen
- River flood very low
- Urban flood very low
- Coastal flood no data
- Earthquake medium
- Landslide high
- Tsunami no data
- Volcano high
- Cyclone high
- Water scarcity medium
- Extreme heat low
- Wildfire high
ThinkHazard, at the scale of Chapala, Jalisco, Mexico — a planning prompt, not a site assessment.
The reading
What the figures mean together, what to do first, how to check it, and what only the water itself can answer.
Findings
- Risk
Something discharges to, or works beside, this water.
A mapped outfall or industrial edge is a point source to ask about before any other question; the map shows presence, never what leaves the pipe.
4 mapped outfalls or treatment plants and industrial land use on the shore within about 3 km, from the public map. · medium confidence
- Risk
The rain that feeds this water has been falling for twenty years.
For a standing water body the trend in inflow matters more than the total: a falling trend is a shrinking budget, felt first at the shallow edge and in the dry season.
Twenty-year rainfall trend -20.1% over the water (reanalysis grid, ~9 km). · medium confidence
- Risk
The division screens high for cyclone.
A screening class at administrative scale — a prompt to read the shoreline and the record, not a site assessment.
ThinkHazard (GFDRR) for Chapala, Jalisco, Mexico. · low confidence
- Opportunity
The water reads clear from orbit.
Clear water is the rarest condition to keep and the cheapest to lose; it says the catchment above is still holding its soil.
Turbidity index -0.1, chlorophyll index 0 over 990 water pixels. · medium confidence
- Permanence
This water has stayed, year after year, for four decades.
Permanence is the first property of a water asset: what stays can be planned around; what comes and goes must be designed for.
98% permanent, 1% seasonal; where water was seen it was present 97% of the time (JRC Global Surface Water, Landsat 1984–2021). · high confidence
- Clarity
96% of the boundary read as open water on the latest clear pass.
The share of the drawn boundary the scene classifies as water says whether the reading is about the water or about its edge.
Sentinel-2 scene classification, 2026-08-26; turbidity clear, chlorophyll moderate. · medium confidence
- Climate
The surface of the water read 25.8 °C on the latest clear thermal pass.
Surface temperature governs how much oxygen the water can hold and how fast it stratifies.
Landsat Collection 2 surface temperature, 2026-08-17; a skin reading from orbit, warmer than the water a metre down. · medium confidence
- The shore
The shore is worked land.
The edge decides what reaches the water: a wooded or wetland shore filters runoff; a built or cropped shore delivers it.
300 m ring: Tree cover 35% · Built-up 22% · Cropland 20% · Grassland 16% (ESA WorldCover 2021, land pixels only). · high confidence
- Life
This water is well recorded by naturalists.
Occurrence counts measure where people have looked as much as what lives here; a thin record is an unknown, not an absence.
3,504 GBIF occurrence records inside the boundary; most recorded: Pelecanus erythrorhynchos, Nycticorax nycticorax, Fulica americana. · medium confidence
- Climate
Expect the seasons here about 2 °C warmer by 2050, with 31% less rain.
Warmer air means warmer, more stratified water and more evaporation; less rain means less inflow. Expect is the honest verb: this is the middle of a range.
CMIP6 (MPI-ESM1-2-XR, SSP5-8.5) 2045–2049 against the 2004–2024 record; longest dry spell expected 88 days. · medium confidence
- Pressure
This water is worked from its shore.
Roads, towns, harbours and works are the pressure the water lives under; each is also a party to any plan for it.
San Luis Soyatlán 4.9 km away; a main road 4.3 km away; 118 harbour, marina or pier features; about 168,226 people within 5 km (OpenStreetMap, WorldPop 2020). · medium confidence
- The body
Lago de Chapala reads as fresh lake.
Kind and salinity set the whole frame: a reservoir has an operator, an estuary has a tide, a lake has a catchment that is its fate.
99% open water, 1 mapped inflow (OpenStreetMap; ESA WorldCover 2021). · medium confidence
- The basin
The water surface sits at about 1,518 m above sea level.
A lake's altitude sets its temperature regime and tells you how far its water has to fall to the next basin.
AWS Terrarium z12 (ETOPO1 below sea level), 37 samples. Bathymetry is ETOPO1-grade (~1.8 km): a screen, never a chart. · medium confidence
What it means together
About 652 mm of rain falls on this water in a year, and the water stays: most of the boundary has held water through four decades of passes.
The shore is worked land (20% cropland, 58% natural), so soil and nutrients move toward the water — and the water reads clear, which says the edge is doing its job.
This is regulated, used water. Any plan for it runs through whoever holds the discharge permit, the harbour or marina: they set conditions the reading cannot see.
Lago de Chapala is workable water that is turning — the plan must come before the capital; the weakest reading is pressure from the edge, and that is where the leverage is.
What to do first
- 1
Ask for the discharge permit and the last monitoring report for every outfall on the map.
A mapped outfall is the one point source you can name; its permit says what is allowed to leave it, and the report says what did.
On the water · Sample E. coli and nutrients 100 m upstream and 100 m downstream of the outfall on the same morning. · before any offer
- 2
Set a vegetated buffer on the worked or built shore, widest where the slope runs to the water.
Only 58% of the 300 m shore ring is natural cover; the edge is delivering what it should be filtering.
On the water · Walk the full ring at the high-water line; map bare banks, drains and livestock access with a phone GPS. · first dry season
- 3
Take a baseline in four bottles before anything changes.
Every figure here is read from orbit or the public record; a baseline on the water is what makes the next reading a trend.
On the water · Temperature, dissolved oxygen, pH and conductivity at the surface and one metre down; Secchi depth; one bottle for E. coli. Same three points every time. · first visit
Open questions
- —Who holds rights to this water — to take from it, to discharge to it, to fish it — and who enforces them?
- —What is in the sediment on the bottom — the memory of everything the catchment has sent down?
- —What is the land above doing this year that the satellite has not caught up with yet?
Sources & method
Lago de Chapala was read from public satellite and open-data records; the sources are named below with their licence and grain. The weights that turn them into the Water Score are not published — the data is public, the lens is the product.
- Place — OpenStreetMap / Nominatim · Nominatim reverse geocodesettlement · live · ODbL 1.0
- Climate — Open-Meteo · Archive 2004–2024 + MPI-ESM1-2-XR to 2050~9 km · 2004–2024 / 2045–2049 · CC-BY 4.0 (data); non-commercial API tier
- Surface water — JRC Global Surface Water · Global Surface Water v1.4 — occurrence & seasonality30 m · 1984–2021 · Copernicus / open (attribution)
- Biodiversity — GBIF · Occurrence records (count + top species)point · live · Mixed CC0 / CC-BY / CC-BY-NC (per dataset)
- Water bodies, works & shore uses — OpenStreetMap · Overpass (natural=water, waterways, coastline, dams/weirs, harbours, industry, aquaculture, outfalls, roads, places, protected areas)vector · live · ODbL 1.0
- Body & shore cover — ESA WorldCover · WorldCover 2021 v200 inside the boundary and in a 300 m shore ring10 m · 2021 · CC-BY 4.0 (commercial promotion: notify due@esa.int)
- Basin — AWS Terrarium (Mapzen) with ETOPO1 bathymetry · Terrarium elevation tiles sampled inside the boundary~10–30 m on land; ~1.8 km below sea level · 2017 (ETOPO1: 2009) · Open (attribution)
- Water optics — Copernicus Sentinel-2 · Scene classification water mask; MNDWI, NDTI (turbidity proxy), NDCI (chlorophyll proxy) over the water pixels of one clear pass10–20 m · live (latest clear scene, ≤ 120 days) · Copernicus Sentinel data — free, full and open
- Surface temperature — Landsat Collection 2 Level-2 · Landsat C2 L2 surface temperature (ST_B10) over the boundary, latest clear scene100 m (resampled to 30 m) · live (≤ 365 days) · US public domain
- Watershed — Global Watersheds (MERIT-Hydro) · Upstream basin + downstream flowpath (screening hydrography)~90 m · MERIT-Hydro 2019 · Open service, no warranty; engine open source (delineator)
- Population — WorldPop · Gridded population 2020 (parcel + 5 km ring sums)~100 m · 2020 · CC-BY 4.0
- Hazard screening — ThinkHazard! · Multi-hazard classes at admin-division scale (screening-grade; hazard sets ~2015–2020)admin division · division report (mixed vintages) · GFDRR open (attribution)
Read 2026-09-18 02:15 UTC in 9.4 s · lens v1