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Tropical Storm Isaias highlights a familiar problem in Anne Arundel: Where does the rain go, and how fast?

Silt flows out of the eastern shore of Marley Creek. - Original Credit:
Silt flows out of the eastern shore of Marley Creek. - Original Credit: (Anthony Frank / HANDOUT)

When the sky opens up, riverkeeper Jesse Iliff worries about the ground around Anne Arundel County.

Have people been putting fertilizer down? Is there a large chunk of stream bank someplace about to fall into the water, filling it with sediment? Have builders covered their worksites appropriately to prevent sediment runoff that leaves creeks looking more like chocolate milk than water?

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The concerns are familiar and refreshed Tuesday when Tropical Storm Isaias dropped 2.47 inches of rain on the region.

Iliff, a scientist and lawyer who works for Arundel Rivers Federation advocating for the South, West and Rhode rivers, got a number of calls from residents concerned about sediment pollution Tuesday and said advocates for the Severn, Magothy, Patuxent and other rivers probably heard the same.

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Iliff took a bike ride to Quiet Waters Park near Annapolis after someone called him to report sediment pollution in Harness Creek, possibly caused by residential construction upstream. He said one of the streams running through Quiet Waters was still cloudy. Part of the problem is being able to legally pin sediment pollution on sources like developments –– it can be done, but would come down to a battle of experts if litigated in court.

Silt flows out of the eastern shore of Marley Creek. - Original Credit:
Silt flows out of the eastern shore of Marley Creek. - Original Credit: (Anthony Frank / HANDOUT)

On Marley Creek in Glen Burnie, Anthony Frank, water steward for the Point Pleasant Shoreland Neighborhood Association, documented and reported a plume of sediment in the river apparently coming from the Tanyard Cove development. The photos showed a sediment fence with water running over the top, which then went through a forest and out into Marley Creek, turning the water light brown.

Iliff said sediment can cover and kill oysters, and when light is blocked in cloudy waters it affects the ability of underwater grasses to produce oxygen, which fish, crabs and other life use to breathe.

The problem has been the same for years: standards in place to control stormwater aren’t adequate for the more intense rainfall events we are seeing because of climate change, and standards that are in place aren’t adequately enforced.

Iliff said one thing that could help would be an emergency alert system for permit holders, which sends them a text message to warn about a heavy storm in the forecast in Anne Arundel.

County Environmental Policy Director Matt Johnston said Monday workers from Inspections and Permits were doing something similar by phone –– calling permit holders and asking them to prepare construction sites for a deluge.

After the storm, work crews are checking to see what damage has been done to erosion and stormwater control devices such as silt fences at construction sites where issues were reported. He said they will be assessing damage over the next few days and will make sure the broken stormwater controls are fixed.

As of 5 p.m. Tuesday, the National Weather Service had recorded 2.47 inches of rain within 24 hours at BWI Airport, and trained spotters in other parts of the county have reported as many as 5.75 inches.

Builders are required to be able to contain stormwater from a one-year storm on-site, which means there is a 1 percent chance such a storm would occur in a year. In 2017, Anne Arundel County updated their rules to define a one-year storm as bringing 2.7 inches of rain or more in 24 hours.

“Three to five inches in a six-hour time period is a deluge,” Johnston said. “Regulations aren’t really designed to store all of that water on-site.”

Iliff said regulators need to balance the need to store stormwater on-site which the physical constraints and consequences of doing so. A stormwater retention pond big enough to hold the rain from a severe storm could need to be several acres large, which means that trees must be cut down.

“It’s a tough balance to strike,” Iliff said. “How do you manage for more stormwater while at the same time preserving forest cover or tree cover on-site?”

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So-called one-year storms are happening more often, and it is the intensity of the events opposed to the total amount of rain that can truly hurt ecosystems, Iliff said. The speed of that water as it moves through non-tidal streams, which often run between and catch the runoff from developments, can cause sediment to be knocked from the bank.

“Streams become a source of pollution as well as a vector for upstream pollution,” Iliff said.

The county’s stream restoration efforts have focused on reconnecting streams with the flood plain. Over time Johnston said streams can become triangle-shaped, with water having dug down into the bed instead of spreading out over a riparian area filled with plants and roots to soften the load. They want shallow trapezoid-shaped streams, he said.

Johnston said the county is also keeping track of all reports of flooding during Isaias, which it will use to make a map that informs future storm and stormwater policy. People should report flood spots using the 311 app, he said.

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