Water Clarity

Water clarity is a measure of the amount of sunlight that can penetrate through the water. Clear waters are indicative of a healthy Bay, though clarity will always fluctuate naturally depending on weather conditions.

Why is good water clarity important?

Good water clarity is critical to underwater bay grasses. The amount of light that reaches these underwater plants growing in the Bay's shallow waters is the single most important factor determining their growth and survival. Fish also need good water clarity to see their food or avoid being eaten by predators.

What causes poor water clarity?

Poor water clarity is usually caused by a combination of:

• Excess suspended sediments.
• Excess nutrients that fuel the growth of water-clouding algae, indicated by high amounts of chlorophyll a.
• The color of the water, influenced by organic materials from tidal marshes.

How do scientists measure water clarity?

Scientists use a device called a secchi disc to measure water clarity. A secchi is a round, black and white disc attached to a rope. The secchi disc is lowered into the water until it can no longer be seen; then, the water line on the rope is noted and measured. The measurement, called the secchi depth, is the measure of water clarity and the depth to which sunlight is able to penetrate through the water.