By Joy Warren
During the Tuesday evening meeting of the White Lake Board of Commissioner’s, a lengthy report was presented by Dr. Chris Shank and Dr. Peter Zamora with the Bald Head Island Conservancy. Drs. Shank and Zamora have been collecting data over the last year regarding the influence of groundwater flows and nutrient inputs on White Lake water quality. They conducted samples of 5 lake sites and 5 ground water transects on 8 occasions. The data gathered included pH and dissolved oxygen, nutrients, and fecal coliform bacteria levels.
There summary of findings included the following: 1) Rainfall makes up 90% and groundwater only 10% of the water supply of the lake; 2) groundwater flows in NE quadrant and out SW quadrant most of the time; 3) no evidence for recent spring inputs from deep confined aquifers; 4) groundwater hotspots of nutrients/fecal coliform bateria located in East and South; 5) lake fecal coliform bacteria highest during winter (opposite of groundwater); 6) groundwater flow small, but important as a long-term source of nutrients; 7) clean groundwater in NE quadrant flowing into the lake with a pH of 4-5; and 8) Alum treatment completely changed lake algae. They indicated there are still unknowns and more needed research – specifically 1) How widespread are main and individual sewer line leaks? 2) What is volume of nutrient inputs delivered via stormwater runoff? 3) Do blueberry farms influence groundwater nutrients and water budget during spring fertilization period? (no noticed influence at the time of their data gathering in summer through winter); and 4) How much N and P are locked up in sediments and live and dead algae?
Several management recommendations were given in their report. Suggestions made were 1) comprehensive wastewater system testing – #1 priority in NE, #2 priority in SW; 2) develop stormwater runoff plan including drainage ditches and lawn pipes; 3) educate citizens about fertilization best practices; 4) reduce bulkheads in favor of vegetated buffers around lake periphery; 5) keep open Turtle Cove weir to reduce residence time of pollutants; and 6) seek funding for future Alum treatments.
Dr. Diane Laurtisen gave an update on the management of Cynobacteria, pH and nutrients in the lake water. Management of shallow lakes usually requires a combination of strategies such as addressing sources of nutrients (both internal and external); addressing uses of the lake that contribute to water quality problems; and controlling/eradicating invasive aquatic weeds (Hydrilla) which requires treatment. She stated that the objectives for managing the lake include meeting water quality standards; maintaining desirable aesthetic conditions; supporting lake-based recreation and tourism; and maintaining natural ecological functions. These were suggested as a starting point for discussion with next step being a productive and collaborative engagement with partners and stakeholders.
Mayor Womble indicated that lake water clarity and quality is an ongoing issue and these groups as well as any interested citizens will continue to meet to determine a management plan for the best interest of the lake. He reminded the citizens that there is a Lake Cleanup Day scheduled for May 11th.
After handling the administrative matters on the agenda, the Board adjourned to Tuesday, April 30th at 5:30 p.m. for a budget committee meeting.