New water quality report supports excessive nutrient and sediment loading

by Carol Cain.(Cain is the technical coordinator for the Maryland Coastal Bays Program) 

With five years of data analyses under their belt, the Coastal Bays Volunteer Water Quality Monitors released a report this June which indicates that excessive nutrient and sediment loads are being delivered to the Coastal Bays and the effects on the ecosystem are measurable in terms of light availability and algal growth.

The data, which represents nearshore water quality, reaches back to 1997 when the Coastal Bays Citizens Advisory Committee decided to implement a volunteer program to collect data in nearshore areas not routinely monitored by local or state agencies. Their work, at 33 sites in all major bays and tributaries, measured chlorophyll, temperature, pH, clarity (turbidity), nitrogen, and phosphorous over the past five years. In 93 percent of those samples, turbidity readings showed insufficient light to support seagrass growth and reproduction. Chlorophyll-a measurements, a function of nutrient inputs, showed acceptable levels slightly more than half the time in Sinepuxent, Chincoteague, and Isle of Wight bays, but reveal an 81 percent failure rate in St. Martins River and a 54% failure rate in Assawoman Bay.     

During seagrass growing season (April through October) all bays met seagrass requirements for nutrients with the exception of the St. Martins River and Newport Bay which averaged eight times the permissible nitrogen standard. Likewise with inorganic phosphate, St. Martins River and Newport bays had unacceptable levels with Newport exceeding the threshold nearly 11 times.

Excessive nutrients often result in algal blooms that shade out seagrass beds, which provide oxygen through photosynthesis. When algal blooms decay and photosynthesis ceases at night, the result is often early morning oxygen depletion, which can stress the ecosystem.  The high chlorophyll, nitrogen and phosphorous numbers collected by the volunteers corroborate a DNR study finished this spring which showed dissolved oxygen levels are often too low for fish, crabs, and shellfish in parts of the northern bays. 

There are many variables that contribute to sediment and nutrient loadings including air deposition, sewage treatment systems, stormwater runoff and groundwater. This report serves as a supplement to scientists studying those very problems and supports their efforts in learning the most effective ways to reduce pollution from flowing into these shallow lagoonal waterbodies. Currently, more than 20 additional sites are monitored by the Department of Natural Resources, the Department of the Environment, and the National Park Service.

To restore the bays, we must understand that water quality conditions must improve and remain within the optimal range for the health and vitality of native species. As scientists determine the ideal habitat conditions for each species, monitoring data will be instrumental in judging how often conditions are suitable for the survival and propagation of these species. Certain water quality parameters such as nutrients, phytoplankton/algae, and sea grasses are very good indicators of environmental health.

Volunteer monitoring is integral in the effort to assess the health of our nation’s waters. Government agencies have limited funds for monitoring and have found that volunteer programs can provide high quality, reliable data to supplement their own monitoring programs. The Maryland Coastal Bays Program and our community is indebted to the support and contributions of our citizen scientists.

The report is available at Worcester County Public Libraries. A summary is available in PDF format online: Summary