“If you don’t like the weather, wait a minute.”
Rapid changes in Casco Bay’s water quality this past week can attest to that.
On Monday, February 22nd, our staff scientists Peter Milholland and Mike Doan saw evidence of the winter’s snow drought in the relatively high salinities at our profile sampling sites. At Broad Sound in eastern Casco Bay the salinity was 34 parts per thousand (ppt), akin to that of the open ocean. At this time of year, they would normally see salinities between 31.0 and 32.5 ppt.
Five days later, after a ferocious rainstorm, Peter and Mike motored out to Fort Gorges in Portland Harbor to check the water conditions there. The salinity at the surface was 32.1 ppt on Monday; on Friday it was 5 ppt. Water clarity, measured with a secchi disk, was 10 ½ feet (3.2m) on Monday but was only 4 inches (0.1m) on Friday.
Five - six inches of rainfall contributed to a wedge of fresh water from the Presumpscot River that reached more than 2 miles out into Portland Harbor, past Fort Gorges.
Sampling for water clarity and chlorophyll also showed that the spring phytoplankton bloom is well underway. The recent rainfall added large amounts of nutrients to help push the bloom into high gear. Unfortunately, the stormwater runoff will also add oil and other chemical pollutants, Styrofoam, and other trash that are ingested by marine life and sea birds.