It is the responsibility of the California Water Boards to protect Californians and their watersheds from polluters, but hundreds of thousands of Central Valley residents currently lack access to safe drinking water. Notably, the burdens of unsafe water disproportionately fall on low-income communities while impairing functioning ecosystems.

Discharges from irrigated agriculture are the largest source of pollution in California’s Central Valley. Water diversions for irrigated agriculture pose significant environmental challenges by diminishing instream flows and depleting aquifers throughout the state. (https://www.impactfund.org/social-justice-blog/cali-coastkeeper?gclid=Cj0KCQiA-aGCBhCwARIsAHDl5x-NEC5PYLd0x4mr6SMcC4b4u-rRPVx9Puyho4yHv2IijpnUh3RvUvYaAtspEALw_wcB) Ahir Haros

When rain falls and seeps deep into the earth, filling the cracks, crevices, and porous spaces of an aquifer (basically an underground storehouse of water), it becomes groundwater—one of our least visible but most important natural resources.
Almost all the beaches in Ensenada suffer from great pollution, for example Playa Hermosa, which shows the great amount of pollution and although the public has been warned that they must take care of the beaches and the rivers they do not take it seriously.
Monique Cedeño

https://www.nrdc.org/stories/water-pollution-everything-you-need-know#whatis

There are several pollutants that are very dangerous if entering our body or the body of any living thing in the planet. Scientists have proved that they’ve found some water bottles that we buy and drink everyday, wich is said that they’re “clean”, contained chemicals like arsenic (a very toxic element) and copper.

Actually, in Ensenada, the public beach is very contaminated. People still go swimming of surfing, but they take the risk to accidentally drink that polluted water. Water may not be lacking here where we live, but that not makes apart that water In Ensenada could be polluted too. What we need to do is to raise awarness of what we are doing to the planet we live in, governments should take responsability of cleaning oceans, rives, and lakes even if that costs lots of money. At the end if we don’t do nothing about it clean water would no longer be possible and we would probably die of thirst, sadly. 
https://www.nrdc.org/stories/water-pollution-everything-you-need-know#:~:text=Harm%20to%20any%20of%20these,oxygen%20levels%20in%20the%20water. 

According to the Ministry of the Environment and Natural Resources (Semarnat), Playa Hermosa, in Ensenada, is the one with the highest rates of enterococci, higher than 263 per hundred milliliters of seawater

Due to the high rate of pollutants on the coast of Ensenada, Baja California, the municipal government of the port decided to close access to the public at Playa Conalep and Playa Hermosa.

He added that this impact was derived from wastewater spills in that area, which has been happening for years, with temporary closures on the beaches to avoid risks to the health of bathers.

 

Water is the basic resource to guarantee the life of all living beings on the planet. However, its scarcity and contamination cause millions of people to have poor access to this much-needed good. Although there are water treatment techniques such as purification or desalination that facilitate the use and consumption of water in areas with quality or supply problems, in the first place it is necessary to avoid its contamination.

Human beings are the main cause of water pollution, which can be affected in many ways: with the dumping of industrial waste; because of the increase in temperatures, which cause the alteration of the water by reducing the oxygen in its composition; or due to deforestation, which causes the appearance of sediments and bacteria under the soil and the consequent contamination of the groundwater.

In the same way, the pesticides used in the agricultural fields are filtered through the underground channels and reach the consumption networks; and also, with the accidental spill of oil.

Some of the many of them will be the disappearance of biodiversity and aquatic ecosystems. Also, the human being is very harmed due to the alteration in the food chain and contracts diseases when drinking or using contaminated water.

 

https://www.sostenibilidad.com/agua/causas-consecuencias-contaminacion-agua/#:~:text=%C2%BFQu%C3%A9%20efectos%20provoca%20la%20contaminaci%C3%B3n,o%20utilizar%20el%2 

The issue has been flaring up again, despite hundreds of millions of dollars invested to build new treatment plants in Tijuana and connect more neighborhoods. Six miles down the coast from the border fence, the city’s largest sewage treatment plant, now three decades old, failing and stretched beyond capacity, has been long overdue for replacement. Across the city, collector pipes are in danger of collapse. A dozen developments on the coastline — and others that are inland — need to be connected to the public system.
The continuing issue of cross-border contamination also lays bare the economic differences between United States and Mexico, and different systems for financing public infrastructure.
Rolando Lizarraga
https://www.sandiegouniontribune.com/news/border-baja-california/sd-me-border-sewage-20180305-story.html

Water pollution is the release of substances into bodies of water that makes water unsafe for human use and disrupts aquatic ecosystems. Water pollution can be caused by a plethora of different contaminants, including toxic waste, petroleum, and disease-causing microorganisms.

What human activities cause water pollution?

Human activities that generate domestic sewage and toxic waste cause water pollution by contaminating water with disease-causing microorganisms and poisonous substances. Oil spills are another source of water pollution that have devastating impacts on surrounding ecosystems.

Other Water Pollutants

Water bodies can be polluted by a wide variety of substances, including pathogenic microorganisms, putrescible organic waste, plant nutrients, toxic chemicals, sediments, heat, petroleum (oil), and radioactive substances. Several types of water pollutants are considered below. (For a discussion of the handling of sewage and other forms of waste produced by human activities, see waste disposal.)

Domestic Sewage
Toxic waste
Sediment

Thermal Pollution
Petroleum Pollution

https://www.britannica.com/science/water-pollution

Oswaldo Rueda