Water Quality Index Score: 80, Fair
Of the nine watersheds we measure in our water quality monitoring program, San Luis Rey had the best water quality index score in 2015. But at 79.9 (roughly a B- or C+) it’s not exactly a stellar grade.
We tracked two parameters of concern in San Luis Rey Watershed:
- Turbidity: Two-thirds of the turbidity samples exceeded healthy standards
- Levels of pH: Over half of the pH samples collected exceeded healthy standards
Turbidity and Tidal Wetlands
Turbidity refers to the cloudiness or haziness of water caused by many small particles generally invisible to the naked eye, similar to smoke in air. Small particles, such as sediment or organic material, in the water make it appear cloudy. When turbidity is high, it’s harder for light to reach the ground, affecting the growth of plants. As well, pollutants like metals and bacteria can hitch a ride down our watersheds in the spaces between these particles.
We especially care about turbidity in the San Luis River because it contains a tidal wetland, a habitat where fresh water meets coastal salt water. Tidal wetlands are vital habitats for species like mullet fish and birds that depend upon a consistent balance of fresh and salt water. If unnatural amounts of sediments build up in this area, they can block salt water from entering the area and disrupt the balance of this critical habitat.