Why rank lakes by phosphorus?

Phosphorus is usually what limits how much algae a lake can grow, so it is the earliest signal that a lake is under nutrient pressure. It is also the measurement these agencies publish most consistently, which makes it the fairest way to compare lakes across a country.

Is a low-phosphorus lake safe to swim in?

Not necessarily. A lightly loaded lake can still carry bacteria, a seasonal algal bloom, or contaminants that a nutrient reading does not cover. Check the local authority notice for the day you plan to go.

What is a typical phosphorus level in Mexico?

The median measured lake in Mexico reads 87.6 µg/L of total phosphorus. Lakes below roughly 10 µg/L are considered nutrient-poor and usually run clear; above about 30 µg/L a lake is generally nutrient-rich and more likely to green up in summer.

Cleanest lakes in Mexico

Cleanest lakes in Mexico: 401 named lakes have an official total-phosphorus reading. The 20 below carry the lowest nutrient load — a measurement, not a LakeQuality A–F grade.

Lake map

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Lowest phosphorus readings in Mexico

Phosphorus is the nutrient that feeds algae growth, so the lakes at the top of this table are the least loaded ones the Mexico monitoring programme has measured. The median measured lake in Mexico reads 87.6 µg/L.

Lake	Place	Total phosphorus	Chlorophyll-a	Secchi	Year
Dam the Country Is First	—	16 µg/L	5.9 µg/L	0.5 m	2021
Laguna Madre Humedal	—	18 µg/L	1.0 µg/L	0.3 m	2020
Nezahualcoyotl Dam	—	18 µg/L	3.1 µg/L	1.6 m	2021
Affluent Pedro Jose Mendez Dam	—	19 µg/L	—	—	2020
Cerro Prieto Reservoir	—	19 µg/L	1.0 µg/L	0.5 m	2021
Alberto Carrera T Dam	—	20 µg/L	2.5 µg/L	2.2 m	2020
La Angostura Dam	—	21 µg/L	4.7 µg/L	1.7 m	2021
Laguna Conil	—	23 µg/L	3.7 µg/L	2.5 m	2020
Laguna Bacalar	—	24 µg/L	0.60 µg/L	1.9 m	2020
Curtain Presa la Amistad	—	24 µg/L	4.8 µg/L	1.5 m	2020
Guadalupe Dam	—	24 µg/L	6.3 µg/L	0.5 m	2020
La Amistad International Dam	—	25 µg/L	3.3 µg/L	1.1 m	2020
La Amistad International Dam	—	26 µg/L	2.7 µg/L	1.0 m	2020
Laguna Sian Kaan	—	26 µg/L	1.7 µg/L	0.8 m	2020
Vicente Guerrero Dam	—	26 µg/L	—	1.1 m	2018
Pedro Jose Mendez Dam	—	27 µg/L	3.3 µg/L	1.2 m	2020
In Front of Gates Lake	—	28 µg/L	4.8 µg/L	1.1 m	2021
Laguna de Nichupte	—	28 µg/L	2.1 µg/L	1.2 m	2020
Las Lajillas Dam	—	29 µg/L	2.4 µg/L	0.5 m	2020
Vicente Guerrero Dam	—	29 µg/L	1.5 µg/L	1.1 m	2020

Showing 20 of 401 named lakes. Open a county or place page for the rest.

Frequently asked questions

Which lakes in Mexico are the cleanest?: 401 named lakes in Mexico have an official total-phosphorus reading. This page ranks the 20 lowest. Phosphorus is the nutrient that feeds algae growth, so a low reading means a lightly loaded lake — it is not a swim-safety class and not a LakeQuality A–F grade.
Why rank lakes by phosphorus?: Phosphorus is usually what limits how much algae a lake can grow, so it is the earliest signal that a lake is under nutrient pressure. It is also the measurement these agencies publish most consistently, which makes it the fairest way to compare lakes across a country.
Is a low-phosphorus lake safe to swim in?: Not necessarily. A lightly loaded lake can still carry bacteria, a seasonal algal bloom, or contaminants that a nutrient reading does not cover. Check the local authority notice for the day you plan to go.
What is a typical phosphorus level in Mexico?: The median measured lake in Mexico reads 87.6 µg/L of total phosphorus. Lakes below roughly 10 µg/L are considered nutrient-poor and usually run clear; above about 30 µg/L a lake is generally nutrient-rich and more likely to green up in summer.