Duncanson: Protecting Bay’s Water Quality A Marathon, Not A Sprint

By: Alan Pollock

Topics: Pleasant Bay

Tranquility at Round Cove. ALAN POLLOCK PHOTO

EAST HARWICH When it comes to restoring the pristine water quality in Pleasant Bay, Harwich, Chatham, Orleans and Brewster are in it for the long haul. It takes decades for nutrient pollution from upland residential development to reach the waterway, and it will take decades to bring nitrogen levels back where they belong, officials say.

That’s not to say there isn’t ample evidence that the health of the bay is improving, Chatham Health and Natural Resources Director Robert Duncanson said at a recent forum held at Pleasant Bay Community Boating. The bay itself is 6,800 acres in size, but its watershed is 21,000 acres, with 11 ponds and 71 miles of shoreline.

“We’ve been messing around with Pleasant Bay for generations,” Duncanson said in the Nov. 9 forum. The earthen dike where Route 28 crosses Muddy Creek, built to replace previous bridges, was made from fill carved out of the Chatham hillside by a horse-drawn grader sometime between 1899 and 1903. Narrow culverts in the berm restricted tidal flow, which was only restored again with the installation of the new bridge in 2016.

In 1987, with help from the Friends of Pleasant Bay, the state designated the waterway an Area of Critical Environmental Concern, “one of the first ACECs in the Commonwealth,” Duncanson said. “It means that any projects going on in Pleasant Bay have to meet the highest standards.” One requirement of the designation was the creation of a resource management plan, which was belatedly adopted by the four towns nearly a decade later. The tool for crafting the plan was the Pleasant Bay Alliance, a quasi-governmental group representing the four towns.

First adopted in 1998, the plan is updated every five years, and the 2018 update includes good information on trends in everything from water quality and shellfish habitat to the number of moorings and shoreline structures. But the Alliance is not a regulatory agency, Duncanson said, and any action it takes must win approval from voters in each of the four member towns.

“You think it’s tough getting one thing through one town meeting?” he quipped.

The plan focuses on topics like water quality monitoring, ecological inventories, waterways management, shoreline structures and public access, “really topics of interest to the towns and the public. We don’t make these things up,” Duncanson said. The Alliance then makes recommendations for the towns’ regulatory committees to consider. “Some have been adopted over the years, and others haven’t been,” he said. But the Alliance has demonstrated one thing clearly: “If you really want to protect Pleasant Bay, you’ve got to have four towns in sync,” Duncanson said.

He last decade has been focused on nitrogen, a nutrient in human waste that passes from residential septic systems, through the aquifer and ultimately into the coastal waters. Towns are required to meet state limits on allowable nutrient pollution, and doing so has prompted towns to expand their sewer systems, providing centralized wastewater treatment in an environmentally-conscious way. Working with the state, the Alliance and the four Pleasant Bay towns recently received the first watershed permit issued in the state, possibly in the nation, with the member towns agreeing to work together to manage nutrient pollution. The effort won an award by the EPA, and serves as a model for other communities. “We basically set the bar for the rest of the Commonwealth,” and maybe for other New England states, Duncanson said.

“Water quality’s been a topic in Pleasant Bay going back decades,” he said. In 1965 and 1967, state officials carried out an inventory of marine resources like eelgrass and shellfish beds. Little additional work was done until the late 1980s, when Boston College researchers documented bacteria levels at various sampling stations. “Back in the 80s and 90s, that was the big issue,” Duncanson said. But there were signs that pollutants other than bacteria were causing problems.

“I was getting the calls every summer” from shorefront residents who complained about stinky, pea soup-green water caused by blooms of phytoplankton. It wasn’t clear what was causing the blooms, and towns initially assumed that nutrients from road runoff were the culprit. Research around the Chesapeake Bay at the same time was pointing to a different source: residential septic systems.

Water quality monitoring has been underway since that time, part of a methodical effort to track changes in nutrient levels, dissolved oxygen and other indicators of a waterway’s health. That water monitoring, done mostly by dedicated volunteers, has formed the basis of efforts to understand changes in Pleasant Bay, and to reverse troublesome trends. The impartial data demonstrates the need for towns to expand sewer systems and make other costly improvements. If towns are going to ask taxpayers for tens of millions of dollars for those projects, “you have got to be able to show that they work,” Duncanson said.

Charts of water quality data show that areas where there is good tidal flushing, like Chatham Harbor, are the healthiest, while the remote reaches of Pleasant Bay, like Meetinghouse Pond and upper Muddy Creek, have the most nutrient pollution. There is variability from year to year, based in part on rainfall, but over time, the data will show improvements over decades, he said. But those changes are unpredictable, thanks in part to the unpredictability of the barrier beach that separates the bay from the Atlantic. Breaks in the barrier beach can change tidal patterns, which can sometimes help water quality.

There was speculation that water quality would improve markedly when the 2007 inlet formed opposite Minister’s Point, and officials are monitoring tide data to judge the amount of water exchange in the bay. “The amount of water going in and out of Pleasant Bay is almost back to where it was prior to the 2007 breach, because so much shoaling has occurred,” Duncanson said.

In the most sensitive sub-estuaries like Muddy Creek, the bottom is covered with organic material from decaying leaves and phytoplankton, and that decomposition itself harms water quality. Instead of a sandy bottom or one with eelgrass, the waterway has dark muck.

“That’s what we call the ‘black mayonnaise,’” Duncanson said. Dredging away the muck wouldn’t be a long-term solution, since it doesn’t address the source of the problem: nitrogen flowing from upland septic systems.

“Remember, Muddy Creek’s been closed off for 100 years. There’s 100 years of organic muck,” he said. Following the installation of the bridge, there have been some modest improvements in water quality.

“We’re starting to see improvement, but we knew from the get-go that this was a long-term proposition,” Duncanson said.

One audience member at the presentation asked Duncanson whether he believed the expansion of sewer systems around the bay is happening at the right pace.

“The short answer to your question is, no. As a scientist, I’d like to fix the problem tomorrow,” he said. But as a town official and a pragmatist, “I’m cognizant of all the other issues.” Chatham had a plan in 1966 to sewer the entire town, but the plan was never put in place. “If they had, Chatham wouldn’t have the problem that it does today,” Duncanson said. But voters make the decisions at town meeting, and Chatham voters have committed nearly $200 million. Other towns are more reluctant to spend.

“If they have to make a decision between a sewer and a school or a fire engine, those are all legitimate concerns,” Duncanson said. “It’s frustrating, but you have to be realistic.”

Email Alan Pollock at alan @capecodchronicle.com
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