The regular August program of the Martha’s Vineyard Garden Club featured Jo-Ann Taylor, the coastal planner for the Martha’s Vineyard Commission for the past 16 years, who spoke about threats to water quality on the Vineyard.
In other club developments, Pat Adler and Laura Lee were installed as president and president-elect.
Ms. Taylor, who used a colored cartoon to illustrate that what goes around comes around in the water cycle, emphasized that the amount of water on the globe is finite and that apart from volcanic eruptions, no new water is created.
The Vineyard receives about 47 inches of rainfall annually. Of that, about 22 inches reaches the water table and the remainder is consumed or lost to evaporation.
A watershed, loosely defined, is an area of land where the water winds up in the same place in the end. A watershed delineation is never a political boundary as watersheds cross town boundaries. Thus, water quality protection must be a communal concern on the Island.
By means of a red-dot map of the Island, the speaker was able to show the extent of population density at the turn of the millennium.
“The most densely populated watersheds may have already shown water-quality impacts,” she said.
But what should concern most people, Ms. Taylor said, are those watersheds with a greater capacity for population growth that have yet to suffer the impact of that growth on the water quality.
In the end, good water quality can help recreational activities, tourism, shoreline views, quality of life, real estate values, commercial and recreational fishing, healthy eelgrass beds and most importantly, our children and their children.
In contrast, imagine a time when collecting shellfish for dinner has become a distant memory.
Monitoring and engendering healthy eelgrass beds is essential to providing a home to fish fry and baby shellfish, she said. Indeed, eelgrass is an underwater nursery.
“Without healthy eelgrass beds, the Island’s marine resources will continue to decline,” Ms. Taylor said.
Excess nitrogen infiltrating coastal ponds was cited as the Island water problem most in need of management.
The audience saw the results of monitoring with a secchi disk, set about eight inches below the surface. It becomes barely visible in soupy green water because of an overabundance of algae. Jellyfish may reflect water quality conditions because they proliferate from an overabundance of phytoplankton. The fouling algae found on mooring lines is another negative signal.
This algae, which blocks sunlight and limits dissolved oxygen, greatly diminishes the habitat for eelgrass which thrives in clear water.
When habitats deteriorate, and oysters and scallops disappear, mud worms provide a sorry spectacle and substitution on our dinner plates. According to Ms. Taylor, Lake Tashmoo lost 42 per cent of its eelgrass in six years. Between 1995 and 2001, eelgrass beds in Lagoon Pond declined by 55 per cent.
Oxygen levels necessary for the survival of fish and shellfish have continued to drop below the water quality standard, Ms. Taylor said. She spoke of how marine life is stressed, particularly in the pre-dawn hours after plants have been consuming oxygen all night.
“Animals like clams will even try to climb out of their burrows and escape,” she said.
Septic systems are the primary cause of excess nitrogen in ponds. Dream lawns have no real place on the Vineyard, according to Ms. Taylor. Those people who insist on fertilizing their lawns should follow directions and use sparingly. Agriculture and storm water runoff, going untreated are further sources of excess nitrogen.
But the nitrogen discharged by the 13,500 individual septic systems on the Vineyard and those yet to be built represents the largest manageable source of nitrogen on the Vineyard. She notes that even an approved, properly functioning Title V septic system discharges nitrogen into the groundwater.
The logical question facing all Vineyarders is what can be done to save the water quality of the Island.
For Ms. Taylor, the answer clearly involves reducing the sources of nitrogen.
She recommends further sewering in the most populated and sensitive areas. She also encourages the use of add-on nitrogen-removing systems with current Title V septic systems.
Further, she said, innovative methods for using nitrogen byproducts from wastewater treatment must be explored. On-site denitrification systems can reduce nitrogen in wastewater by as much as 40 to 50 per cent. A recirculating sand filter is one alternative and hope lies in the new technologies becoming available in the future.
Also, restructuring and improving pond conditions by dredging to improve tidal flushing, reestablishing eelgrass, and increasing shellfish production are some of the promising steps being taken to maintain the quality of our Island waters.
At the end of the program, audience participants were determined to take responsibility for improving the Island’s water quality.