Whether doing cannonballs off the boat, taking off from the dock on a personal watercraft or swimming in the open bays, it’s nice to know how clean that water really is. And the Center for the Inland Bays’ second Recreational Water Quality Indicator Report can help in navigating the use of some of the local inland bays.
The CIB published its first report last year using data from the years between 2004 and 2008, and this year added data from 2009. The data comes from the University of Delaware Citizen Monitoring Program and the Department of Natural Resources and Environmental Control, which tests 30 sites within the inland bays watershed for enterococcus – a type of bacteria that can indicate the presence of other harmful bacteria and pathogens. The testing was equally distributed between three types of sites: open, unrestricted waters of the bays, residential canals or marinas, and tributaries.
“It’s a fantastic data set,” explained Chris Bason of the Center for the Inland Bays.
According to the report, on average, open bay sites exceeded standards 13 percent of the time; residential canals and marinas exceeded standards 19 percent of the time; and tributaries exceeded standards 43 percent of the time.
Certain sites of each type had relatively higher levels of enterococcus, which could suggest site-specific sources.
Upper tributaries had the highest levels of enterococcus. Bason explained that “this is likely due to their proximity to watershed bacterial sources and lower salinities, which are more hospitable for their survival,” sourcing a report by Mallin et al. in 1999 and Mallin et al. in 2000.
The open bay site Pot Nets Seaside Pier never exceeded the standard, and hasn’t done so over five years of sampling, while Dirikson Creek and Upper Guinea Creek had the highest levels of exceedence, at 80 and 87 percent.
Those three extremes were the same as in last year’s report, with Pot Nets never exceeding the standard, and Dirikson Creek and Upper Guinea Creek having the highest levels. (Last year’s report had their numbers at 76 and 89 percent, respectively).
Bason explained that 2009 – the year they added to the report for 2010 – was a year with relatively high levels of bacteria concentrations, but he was quick to dismiss the formation of a trend just yet.
“Six years is getting there but is not really enough to see any trends,” he said. “You do notice that canals and marinas and tributaries for 2009 have, by far, the highest average indicator of organism concentration. But you have to be careful with that, because it is only one year.”
He added that it is still good data and helpful to share with the public.
As to what the report means – especially in terms of how it relates to the signs posted in some locations that caution against swimming in the inland bays – Bason said the information can serve as a way to put the advisories into context and to educate the recreational water user.
“It’s useful information,” he said. “In general, bacteria levels really vary depending upon where you are in the bays. On one side the shoreline of the open bays, you have fairly low levels, and that’s a good thing. On the other side, the tributaries regularly exceed the standards.”
“The bottom line,” Bason said, “is we want clean water and safe and happy swimming, and the more that you use the water and the more you enjoy it, the more you’ll want to protect it.”
He added that everyone can do their part to maintain the integrity of the bays.
Open bay sites tested were Pots Nets Seaside Pier, Massey’s Landing Boathouse Pond Entrance, Warwick Cove, Mulberry Landing, West Bay Park, Keenwick at Roy Creek, James Farm Pasture Point, Fenwick Island Bayside, Holts Landing and Tower Road Bayside.
Tested tributaries include Vines Creek, Mouth of Guinea Creek, Lewes – Rehoboth Canal, Herring Creek, Mid-Guinea Creek, Love Creek, Assawoman Canal Bridge, Burton Prong, Dirickson Creek and Upper Guinea Creek.
The residential canals or marinas tested were Bethany Marina, Bay Colony, Holly Terrace Acres – End, Keenwick Sound – Entrance, and, in South Bethany, the Anchorage Canal at Route 1, Anchorage Canal elbow, Petherton Canal at Route 1, Layton Canal, Carlisle Canal, Russell Canal and Jefferson Canal.
The report is available online at www.inlandbays.org, along with links for more information and more frequent water quality reports from the UD Citizen Monitoring Program and DNREC.