The word "ditch" doesn't conjure up good feelings about water quality, wildlife habitat, or aesthetics. But a new kind of ditch is offering serious opportunity for the Eastern Shore's Talbot County to meet its nitrogen reduction goal under the Chesapeake Clean Water Blueprint. The goal is restoring fish, crab, and waterfowl habitat in waterways like the Choptank and Miles Rivers.
For a long time, we humans designed "funnels"—stormwater pipes and U-shaped open ditches—to substitute for natural streams in moving rainwater quickly away from inconvenient places like roadways and farm fields. Trouble is, the folks who designed them didn't pay enough attention to the way natural streams "work" with rainfall, so over time, the pipe/ditch systems filled with sediment in some spots, eroded in others, and degraded the quality of the water that moved through them, picking up pollutants from the land and carrying them downstream.
Then some enterprising civil engineers in the Midwest had an idea. Suppose they designed two-stage ditches that mimicked nature by providing a small central channel sized to accommodate average natural (base) flow, with "benches" (floodplains) on either side for overflow. Plant the benches with native wetland grasses and they would allow the ditches to catch water from heavy storms, slow it, and let some of it percolate into the soil, where the grasses' root systems would catch sediment and soak up nitrogen, phosphorus, and even some toxic chemicals.
Sound intriguing? That's what CBF's Eastern Shore Office Director, Alan Girard, thought when Amy Jacobs of The Nature Conservancy's Maryland Chapter told him about the idea over coffee one morning. Jacobs was exploring the use of LIDAR (laser-based LIght Detection And Ranging) deployed from aircraft to plot drainage patterns on farm fields leading to Talbot's system of roadside ditches. Girard realized the system might offer a "two-fer" by catching and treating runoff from both the fields and the roadways. The widened ditches take some extra land from both farms and road rights-of-way, but LIDAR allows designers to focus strategically where the ditches provide the most benefit. In terms of cost per pound of nitrogen removed from county waterways, the two-stage ditches offered an attractive, inexpensive alternative to complex urban stormwater retrofits.
The concept is good, but what counts for restoring waterways is putting these ditches to work in the right places. Thus the effort had to blend technology with local politics and public administration. Siting and building them requires teamwork from two agencies, the Department of Public Works (for roadways) and the Talbot Conservation District (for farmland), plus funding. At this point, Alan Girard brought multiple players together to build that team and raise grants for several pilot projects. The discussions included County Council members, staffers from the two agencies and the two nonprofits, and—very important—farmers cultivating land adjacent to county roadways.
The result of the discussions was a $100,000 capital budget item in the 2015 Talbot County budget, which allowed the pilot programs to begin. This year, the county set aside another $50,000 for more ditches and for monitoring their effectiveness. The major challenges now for the project partners are to refine and standardize the techniques, employ the County's funds as leverage for larger grants, and go to work on other priority ditches across the county. The Talbot Ditch Project is essentially about applying an agricultural Best Management Practice (BMP) to suburban stormwater runoff pollution. If early results continue, the two-stage ditch technique has great application for other counties and towns on the Eastern Shore, and in other rural areas of the region. "It's a cheap, simple, common-sense approach that doesn't take much land away from farms or roadways," concluded Girard.
Thought this story would be about crabs, rockfish, and Chesapeake science? Well, it is. Who knew that Saving the Bay would turn out to be about Midwestern engineering, ditches, lasers, excavators, and local government, all working together for clean water? That's the kind of creative partnership thinking that gets this job done.
—John Page Williams, CBF's Senior Naturalist