How do government and nonprofit agencies assess water quality? How do they know what effects a storm or agricultural practice has on stream health? WMRA's Randi B. Hagi tagged along on a demonstration and filed this report.
[stream running, insects and birds calling]
War Branch is a small stream that winds through the poultry, beef, and crop land of Rockingham County before joining Smith Creek, a tributary of the North Fork of the Shenandoah River. It's the site of a monitoring station where the U.S. Geological Survey is studying how farm conservation practices – such as cover crops and fertilizer management – affect water quality. The fact that it's a relatively small watershed makes it unique to study.
JIMMY WEBBER: It's draining about 10 square miles of land area up above us. So that's still a lot that can happen in that area. A lot of farms, a lot of different activities. But most of our longer-term monitoring networks are in larger rivers and streams – think hundreds of square miles. … It's really hard in those systems to identify specific activities causing changes in the stream chemistry.
Jimmy Webber, the Chesapeake Bay associate coordinator for the USGS, led a group of 20-some attendees on a field trip to see the monitoring station. The trip was a part of the Choose Clean Water Conference held in Harrisonburg in mid-May. The group walked through hayfields and pastures down to the grassy stream banks of the War Branch site. Established a year ago, it's one of five watersheds in the ongoing study. The others are in Delaware, Maryland, and Pennsylvania.
Monitoring equipment that lies in the stream collects data and uploads it to an online database about every 15 minutes. It's a metal tube with smaller cylindrical sensors extending from the end – it kind of looks like a cross between a caulk gun and a gatling gun. A tiny motorized brush sweeps off the end of the sensors before each data reading. As Hydrologic Technician Laura Yates explained, the sensors are gauging metrics including water height, turbidity, and dissolved oxygen. She pointed out another one to the group.
LAURA YATES: It's what's called an optical sensor, so it uses a beam of light to measure the concentration of nitrate in the water. It associates the particular wavelength of nitrate with a concentration. We don't have these at every site – it just depends on the goals of the project, and what exactly we would like to know from that continuous site.
Nitrate is of particular interest here – it's a form of nitrogen which, due largely to agricultural runoff, is a major pollutant in the Chesapeake Bay.
YATES: When you're studying best management practices for agriculture … the goal of a site like this is to … see how those practices impact water quality.
Another way to assess stream health is by looking at what all little critters are living in the streambed – referred to as benthic or aquatic macroinvertebrates. The Izaak Walton League of America, a national conservation organization, trains water quality monitors for the Save Our Streams initiative. They currently monitor 200 sites across Virginia, share their data with the Department of Environmental Quality, and publish it online.
Clean Water Program Director Samantha Puckett gave a demonstration during the field trip. She and Matthew Kierce, Chesapeake monitoring coordinator, waded into the creek with a flat, yellow kick-net.
[water splashing]
SAMANTHA PUCKETT: I'm going to rub the rocks for 40 seconds, and then I'll disturb the substrate for 20 seconds. Rubbing rocks looks like picking up cobbles – which is like lemons to cantaloupe-size, and it's like rubbing a bar of soap when you're washing your hands. You don't want to pick up rocks and rub them together, because that's just making bug soup.
They hauled up the net, set it out on a table, and got attendees to pick through it with tweezers, looking for bugs.
PUCKETT: And if, after a while things start to get still, and you're like, "wow, I can't see anything," what you can do is you can spray it and they start to wiggle for you. [sprays water bottle]
Once they've identified everything in the net, they'll quantify the species to get an idea of how that waterway is doing.
PUCKETT: Based on what we're seeing – I haven't done the math, obviously, we haven't had a chance – but based on the stoneflies and mayflies, the case-making caddisflies, we have some good beetle larva between the water-pennies and the riffle beetle adults there, I would say this is a pretty healthy stream.
ATTENDEE: Very healthy, ooo!
PUCKETT: We're not seeing a lot of blackflies and midges, which is an aquatic worm. They tend to be the bulk of the population in very polluted streams.
[walking through field]
Steve Cornia attended the conference with a group from the Eastern Pennsylvania Coalition for Abandoned Mine Reclamation.
STEVE CORNIA: I collect flow and I collect water quality samples. So we're a small nonprofit. We only have four full time employees, so we do what we can with the equipment we have. … You know, it's nice to get ideas and see how they're treating their samples, and get ideas for what we could do. Same thing with the macros –
That's macroinvertebrates.
CORNIA: Yeah, I learned some techniques from that.
War Branch is part of the Smith Creek Showcase Watershed – a U.S. Department of Agriculture project that launched in 2010 to demonstrate how agricultural practices can improve the health of the Chesapeake Bay.
