Mitigating Nutrient Loading on the Choptank

Choptank Riverkeeper Matthew Pluta using a handheld YSI multiparameter meter to conduct readings on the Choptank River in Maryland. (Credit: ShoreRivers)

One riverkeeper organization is focusing on outreach efforts with the local agricultural community to bolster water quality improvement efforts in Maryland’s Choptank River.

ShoreRivers is a nonprofit organization working to improve the health of eastern shore waterways near the Chesapeake Bay. The organization formed in 2017 when the Chester River Association, Midshore Riverkeeper Conservancy, and Sassafras River Association merged. ShoreRivers currently monitors four rivers on the eastern shore with the Choptank being the largest. Starting in Delaware, the river winds for 68 miles through four counties in Maryland before draining into the Chesapeake Bay in Dorchester County. 

“The Choptank River is the most polluted – and also the largest – river entering the Chesapeake from Maryland’s Eastern Shore,” said Matt Pluta, the ShoreRivers Choptank Riverkeeper. “The dominant land use in our area is agricultural so the river suffers the most from nutrient loading and sediment runoff from that sector.”

The river runs along marshes and old-growth forests and is the home of many aquatic species including oysters, clams and crabs. This makes the excessive nutrients from agricultural fertilizers and farm animal waste a major problem. Too much nitrogen and phosphorous in the water led to algae growth and a lack of oxygen for the aquatic life. The lack of oxygen means the fish and other species must either migrate or perish.

In addition to the agricultural effects on the water, the commercial fishing industry contributes to the problem by stirring sediment and destroying the underwater grasses during oyster and clam dredging.

“A healthy oyster reef is one that is growing three-dimensionally into the water column,” said Pluta. “In our area, we became accustomed to the reefs being only flat bars because the oyster and clam habitats were being destroyed.”

Combined, all of these factors led to the organization’s development of a robust water quality monitoring program. The program is based on scientific protocols developed by the Mid-Atlantic Tributary Assessment Coalition and includes 50 sites along the Choptank. Pluta monitors the river with the help of 30 specially-trained citizen-scientist volunteers.

“The volunteers are the backbone of our program because in addition to the sampling sites on the Choptank, we have over 200 other sites on the other rivers that our organization monitors,” said Pluta. “There’s no way we could accomplish that without them.”

From May through October, the team collects monthly water samples that are sent to a laboratory for analysis. The samples are specifically tested for chlorophyll-a, total nitrogen, and total total phosphorus.

The team also uses YSI Multimeter Pro Plus and YSI Multimeter ProDSS handheld multiparameter meters to measure temperature, pH, salinity, and dissolved oxygen at the top and bottom of the river.

Using the Mid-Atlantic Tributary Assessment Coalition protocols, the team uses the data to run calculations that grade the parameters and the sampling sites, and then perform comparisons. Until last year the collected data was entered by hand into a database to do the calculations.

“Last year we worked with local developer Chesapeake Commons and had them use the protocols to write a program that automatically runs the calculations for us,” said Pluta. “That really speeds things up for us. What used to take us months to do, now takes a fraction of that.”

ShoreRivers water specialist stands near a wood chip bioreactor installed on a local farm in Maryland. (Credit: ShoreRivers)

The data is reported to government agencies and loaded to the organization’s new public website, Riverwatch. The website allows the public to access the nutrient levels and other water quality parameters.

PIONEERING SUSTAINABLE AGRICULTURAL METHODS

In addition to monitoring the river, ShoreRivers predecessor wanted to tackle the problem at its source. To do this the organization looked to new sustainable agricultural methods that could be implemented by their local community and ways to make those methods more affordable.

“Through outreach efforts and the use of state resources, we have been able to work with our local farming community to educate them on available sustainable practices,” said Pluta. “They have really stepped up and adopted these practices.”

The efforts have focused on two main sustainable methods, a trend-setting cover crop program and the installation of the state’s first wood chip bioreactors.

According to the state of Maryland website, cover crops help protect waterways from nutrient runoff, controlling erosion, suppressing weeds and improving the soil for the next crop. They may even help farm fields recover more quickly from drought and heavy rainfall. Crimson clover, rye and barley are all commonly used cover crops.  The state offers grants to help offset the cost.

“It’s great to drive through the eastern shore of Maryland in the wintertime and see all of the green farm fields,” said Pluta. “Bare soil during the wintertime accelerates sediment runoff.”

In addition to being an active supporter of the state’s the crop cover program, the organization also introduced the benefits of wood chip bioreactors, which help filter nitrogen out of the surface water. The practice involves the installation of a subsurface trench filled with wood chips along the outer parameter of the farm land. The wood chips become a home to bacteria that digest the nitrogen. When the water finally flows into the nitrogen levels are lower. When practiced in the Midwest, wood chip bioreactors showed a 30 percent reduction in nitrogen.

“We installed our first bioreactor in 2013, and now have five installed throughout the watershed. We were able to secure the funding for the bioreactors so there was no cost to the farmer,” said Pluta.

After installing the bioreactors, the organization set up automatic samplers to test the water that flows in and the water that flows out after being filtered through the woodchips. The organization uses a NuLAB and ISCO Avalanche automatic nutrient monitors and a Solinst water level logger.

The NuLAB model is capable of various simultaneous analysis and is customizable. It includes individual channels for the analysis of nitrate, orthophosphate, ammonium and silicate.

“The automatic samplers run off of solar power and collect a sample every hour,” said Pluta. “We also set them to collect a sample during storm and baseflow events to monitor the effectiveness of the practice.”

Monitoring results have shown a 30-60% load reduction of nitrate nitrogen in the water passing through the practice.

With the monitoring effort running smoothly and the new sustainable methods in place, ShoreRivers is looking to the future.

“We are planning to turn our current monitoring program into a higher tier monitoring system by collecting more parameters and data at each site. We want the data to be even more credible to state and federal agencies,” Pluta explained.

Additionally, a new grant will allow the organization to work on conservation drainage. The effort will allow the organization to work with local farmers to update land drainage systems.

“With the support of our volunteers, the cooperation of our agricultural community and the investment from our state government agencies, we have many great things happening,” said Pluta.