What are Agricultural Restoration Services?

ARS is a leader in the design and implementation of cutting edge, nature-based solutions to some of the complex environmental challenges associated with agriculture. We identify and design innovative solutions from denitrifying bioreactors to cascading treatment wetlands. ARS sets the standard for agricultural conservation practices. We assist landowners to obtain cost share when available and have established creative partnerships with farmers that can lead to impactful projects that generate a twenty-year income stream.

About ARS

CEO, Drew Koslow, formed ARS to help farmers address excess nitrogen, not utilized by crops. ARS has built 11 denitrifying bioreactors and demonstrated that bioreactors are a cost-effective tool for removing nitrogen from water. ARS is partnering with farmers to implement nitrogen reducing practices and to provide farmers with a predictable income stream in a highly variable occupation.

Our business model is based on the establishment of partnerships with farmers in which we share the costs of design and construction of projects and share the profits generated.

Sample Projects

ARS partners with farmers, NRCS, Universities and NGO’s to implement landscape scale conservation practices. We utilize nature-based solutions to create efficient, effective and functional projects.

Koslow brought denitrifying bioreactors to Maryland and has built 11 of them. They are nature-based practices that are cost-effective and highly efficient at removing nitrogen from water. What makes them unique is that nitrogen reductions can be directly measured by sampling at the inlet and the outlet. By measuring flow, the removal rate can be easily calculated. This adds 100% transparency to the practice efficiency and nitrogen removal.

ARS also has experience with design,

permitting and construction of:


  • Denitrifying Bioreactors
  • Denitrification walls
  • Phosphorus-sorbing filters
  • In-line water control structures
  • Wetlands
  • Cascading Wetland Systems
  • Bioretention (in field)
  • Bio-swales

Farmers We Have Worked With

Hutchison Brothers
Ed Fry, Matt Fry
Bill Mason
Trey Hill
Dick Edwards, Scott Edwards
Bill Collier
Joseph Layton


Yancey Bioreactor

High levels of nitrogen have been running from the Smith Creek Headwater Spring into Smith Creek and The Shenandoah River. High nitrogen levels promote the growth of algae and cause eutrophication. These growths quickly use up the oxygen levels in the water and block sunlight from reaching the water column. Restoring the natural balance of the watershed requires lowering nitrogen inputs to normal levels.

By constructing bioreactors near the source of the excess nitrogen before it flows downstream, the watershed is protected from these detrimental effects. Bioreactors work using natural materials and processes and are highly effective at promoting removal of nitrogen from the water.

ARS worked with many partners including USDA Natural Resources Conservation Service Harrisonburg Office, Virginia Tech, The Smith Creek Partnership & US Geological Survey to construct this project that reduces nitrogen flows to Smith Creek.

This aerial shows how we diverted water from the source of the spring to a buffer area 600’ away. There we excavated a pit that holds 800 cubic yards of wood chips which hosts bacteria that convert nitrate, a water soluble and biologically available source of nitrogen, into nitrogen gas that makes up 70% of the air we breathe.
Once we excavated the pit, we lined it, plumbed in the spring diversion, and then added wood chips.
Once the wood chips are in, we covered them with about 1 foot of dirt and then planted grass seed to stabilize the site.

The treated water is discharged into a rock spillway to reoxygenate it before it returns to the stream.


In areas with elevated nitrogen levels in groundwater, a single spring can discharge tens of thousands of pounds of nitrogen each year.


By diverting the springs into a bioreactor, thousands of pounds of nitrogen can be reduced in a cost effective manner. Spring bioreactors are highly efficient and operate for approximately fifteen years. A single bioreactor treating between a quarter of a million and one million gallons of spring flow each day can be expected to remove between 1,500 and 12,000 pounds of nitrogen each year.


ARS partnered with The town of Harrisonburg, Virginia had a diversion in place to take water from Sieberts Creek into a pond in Purcell Park. We intercepted the pipe and diverted the water into a bioreactor. The water is retained there for 8 hours before flowing to Black’s Run. This project protects the North River. On the Yancey farm, east of Harrisonburg, we constructed a second spring bioreactor in 2020 with a similar design, removing excess nitrogen from the Smith Creek Headwaters Spring, Smith Creek and the Shenandoah River.


We estimate that the Sieberts Creek project alone will remove 1365 lbs of nitrogen per year from Blacks Run, which drains to the North River. Similarly effective nitrogen removal is expected from the Yancey Farm bioreactor treating the Smith Creek Headwaters Spring. Researchers from Virginia Tech have documented the Yancey project removing approximately 1,200 pounds of nitrogen per year.


Massey Farm Cascading Wetland System

Partners: Harbor View Farms, Sassafras River Association, Ridge to Reefs

Funders: Maryland Chesapeake and Atlantic Coastal Bays Trust Fund and Maryland 319 funds

Cascading Wetlands Treatment System

These practices supercharge the treatment properties of wetlands and enable them to be utilized in large drainage areas. Our cascading wetland systems maximize the treatment in watersheds that range from 75-100 acres.

2015 aerial image of the project area. The dark shaded drainage was previously maintained as buffer because of the unmanaged runoff draining to it.

This 2018 aerial photo shows a rock lined forbay to reduce the erosive force of water draining towards the wetlands, and three wetland cells

Wetland cell one 2022

Wetland cell 3, 2022

Other Projects

In line water control structures- Collier Farm, Henderson, MD.
Denitrifying Bioreactor and denitrification wall- Oakland View Farm, Ridgely, MD
Denitrifying Bioreactor and denitrification wall- Mason’s Heritage Farm, Centerville, MD
Denitrifying Bioreactor- Franklinville Farm, Cordova, MD
Denitrifying Bioreactor- Bradbury Farm, Cordova, MD
Denitrifying Bioreactor and Phosphorus filter- Fair Hill Farm, Chestertown, MD
Denitrifying Bioreactor- Meadow View Farm, Cordova, MD
Cascading Wetlands Treatment System and biochar enhanced infiltration trench- Colchester Farm, Galena, MD
Cascading Wetlands Treatment System, biochar enhanced infiltration trench, biochar enhanced, in field bioretention area- Harbor View Farms, Massey, MD
Denitrifying Bioreactor and wetland creation/restoration- Elgin Farm, Worton, MD
Denitrifying Bioreactor- Layton’s Chance Winery, Dorchester County, MD
Denitrifying Bioreactor- Purcell Park, Harrisonburg, VA
Denitrifying Bioreactor- Yancey Farm, Keezletown, VA
Denitrifying Bioreactor- Chalk Point Power Plant, Aqausco, MD
Denitrification Wall, bioswale and in-field bioretention- Morton Farm, Two Johns, MD.

Contact Us

1 + 5 =

Drew Koslow, CEO

411 North Street

(410) 533-2753