Dissolved Organic Carbon

Nutrients (nitrogen, phosphorus, carbon) are the building blocks for life, but too much in a natural system can lead to problems. Our communities contribute excess nutrients to the Sound from wastewater, septic systems, fertilizer, and fossil fuel burning. Nutrients fertilize excessive growth of plantlike organisms, leading to algae blooms. As these organisms and the animals that feed on them respire, die, and decompose, oxygen in the water is depleted.

Dissolved organic carbon is relatively stable, making it a good indicator of human impacts. Most human sources of nutrients are high in dissolved organic carbon.

How is it measured?

Dissolved organic carbon is collected at 23 stations up to 30 times during the period of interest (January to December). Water samples were taken into a lab where dissolved organic carbon analysis occurs. 

Threshold Levels

Criteria Threshold Overall Score Calculation
 < 1.65 mg/L 90% - 100%
 1.80 - 1.65 mg/L 80% - 90%
 1.95 - 1.80 mg/L 70% - 80%
 2.10 - 1.95 mg/L 60% - 70%
 > 2.10 mg/L  < 60%