Mosquito Creek watershed project highlights acid rain mitigation success and blueprint for others

The first Mosquito Creek Watershed acid rain mitigation treatment system was built at Ardell Road in 2001.

Riverkeeper's note: The following blog post was written by West Branch Regional Director Andrew Bechdel. He can be reached via email by clicking here.

Long before Jacob Smith ever stepped foot in the Mosquito Creek Watershed to fish for native brook trout, the Mosquito Creek Sportsman’s Association and Terry Rightnour spearheaded a restoration project to improve their watershed impaired by acidic deposition.

More than 20 years later, Smith, now a young staff engineer with the ARM group LLC, has taken the reigns of the Mosquito Creek restoration project and monitoring its treatment systems.

Smith first heard about the Mosquito Creek restoration project while studying acid deposition abatement on Bowman’s Creek (Wyoming County) at Wilkes University in Northeastern Pennsylvania.

​“I kept hearing about this project on Mosquito Creek that had been completed, I ended up reaching out to Terry Rightnour who completed the project … that was how my role started here at the ARM group," said Smith, whose experience with acidic deposition mitigation as an undergrad made him a good fit for the project.

​The Mosquito Creek Watershed is one of the most remote areas of the Susquehanna River Basin. It lies west of Karthaus (Clearfield County) and the West Branch. The watershed features over 180 miles of stream that runs through mostly public land, including the Quehanna Wild Area, State Game Lands 34 and Moshannon State Forest.

According to Smith, the watershed is already naturally acidic due to its geology but is also affected by acidic deposition.

These are higher elevation streams that are underlain by shale and sandstone geology," he said, adding that “there are no natural carbonates present in the geology."

Without these natural carbonates, the streams are unable to neutralize acidity that may be added to them.

While the native brook trout are relatively tolerant of these low pH environments, their food source, the aquatic macroinvertebrates – or "stream bugs" – are not.

"Acidification in general tends to really hurt the macroinvertebrate populations," Smith said. "If you have anything that’s affecting your macroinvertebrate populations, you’re going to be affecting your fish populations."

According to Smith, the restoration project started with Rightnour and the Mosquito Creek Watershed Association in the late 1990s when Mosquito Creek was experiencing acidic stream conditions.

“Terry believed that he had a technology that could address it and wanted to pursue it. So, he did an extensive watershed plan and designed and built five treatment systems from 2000-2014," said Smith, pointing out that Rightnour “was trying to develop these technologies to be used elsewhere, not just the Mosquito Creek Watershed."

Rightnour was brought onto the project by the Mosquito Creek Sportsman’s Association to find an alternative to adding alkalinity to the watershed and help them apply for a Growing Greener Grant.

According to Rightnour, they wanted to restore what was a premier fishery 40 years ago.

"The lowest pH occurred in the spring runoff when there was a heavy snowpack," he said. "Most of them are episodically acidified," meaning the watershed only experiences the strong acidification during high-flow events. Rightnour began looking through the data to determine the best locations to put treatment systems. 

Funding for the project came from the Growing Greener Grant. The grant was awarded in 2000 for the construction of the first treatment system, Ardell Road, which went online in late 2001. It has been producing alkalinity and neutralizing water ever since.

Duck Marsh Treatment System was built in 2003, helping offset acidity in the headwaters of the Mosquito Creek watershed.

The next two treatment systems, Duck Marsh and Pebble Run, followed and were built in 2003 and 2004 respectively. All three treatment systems add alkalinity to the headwaters of Mosquito Creek. 

The last treatment system, Lost Run, was built in 2014 as part of a mitigation from the proposed river hills power plant and serves Gifford Run.

The treatment systems are referred to as "vertical flow limestone beds" technologies, or more recently: Vertical Flow Limestone Beds.

Located in headwater watersheds, the systems add alkalinity to the headwaters streams using a 100-foot by 100’-foot (10,000 -square-foot) manmade basin of organic compost and high calcium carbonate limestone to treat 100 gallons per minute of intake water with limestone, a natural carbonate, before discharging it back into the stream.

Smith refers to this process as “adding buffering capacity."

This High Flow Buffer Channel at Lost Run helps add alkalinity to Gifford Run and other areas of the watershed.

Additional technologies, such as the High Flow Buffer Channel at Lost Run, add alkalinity to Gifford Run and other areas of the watershed. The details of these systems can be accessed in the Mosquito Creek Phase 4 report. The vertical flow wetland systems work to add buffering capacity at all flow rates, while the Gifford Run high flow buffer channel works to add buffering capacity only above a bank full event.

The construction and maintenance of the treatment systems has been relatively inexpensive – about 1.5 million – compared to similar restoration projects.

"We designed them for 20 years, but we’ve had the Ardell system for longer than that," said Rightnour. "If they every do need refurbished, the structure is already there, all you would have to do is replenish the limestone and compost"
 
According to Smith, these systems were originally used to treat streams affected by abandoned mine drainage.

“This was the first time that I’m aware of that these systems were used to add buffering compacity to a stream affected by acidic deposition, and most certainly to this scale," he said.

Typically, streams affected by abandon mine drainage are also laden with high concentrations of toxic metals, such as iron, manganese and aluminum. Since the Mosquito Creek Watershed is only affected by low pH, the treatment systems did not need to remove metals from the water. Due to this fact, the systems have been virtually maintenance-free for the past 25 years, including a lack of flushing as other AMD treatment systems require.​

Lost Run is the most recent treatment system in the Mosquito Creek watershed, built in 2014.

The last report on the state of the Mosquito Creek Watershed and its treatment systems was in 2006. Now, Smith is interested in how these treatment systems, which typically have a 20 to 25-year lifespan, are functioning. Although these treatment systems have almost reached their proposed lifespan, he says that he believes they could last another 10-15 years from current values.

"There isn’t an area of the watershed that isn’t beautiful," said Smith, speaking to a vast wilderness were elk are often more common than people. This natural beauty was even taken into consideration when constructing the systems.

"We wanted to have systems that blended in with the area," said Rightnour, and “didn’t look industrial."

Today, the watershed is thriving. Smith recently fished Gifford Run, a tributary, and caught nearly 20 native brook trout.

Additionally, water sampling above and below the treatment systems shows an increase in the macroinvertebrate communities below the treatment systems. Smith even has seen young-of-year brook trout in the treated effluent.
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The abundance of great flyfishing opportunities in the watershed is proof that the treatment systems are working and illustrates the success of the restoration project. ​