Roadside ditches and water management

The tropical weather continued last week throughout our region, as daily flash flood watch alerts have been issued in many localities.

It could be worse! Coastal New Jersey, where I know some of you readers live, has been particularly hard hit. I have family in Carteret, N.J., and some of the pictures I have seen from there are pretty frightening.

Closer to home, the Catskill, Kaaterskill, Batavia Kill and Schoharie creeks and most of their tributaries look like raging streams of chocolate milk right now. Once the soils are saturated, all excess rainfall just runs off into them. This is exacerbated by the ditches that line most of our back roads.

Roadside trenching of vegetation is a major contributor to erosion and from a strictly ecological perspective, it is a nightmare.

The following is from a Cornell University fact sheet that can be found here http://bit.ly/2MSs4CH (PDF)

I really wish that our state and local highway department officials would read this and try to implement some of the practices outlined. From the fact sheet: “We all live in a watershed, and precipitation is the lifeblood of a watershed. When rainfall pounds impervious surfaces and compacted soils, it runs off rapidly instead of percolating down to the groundwater. The runoff can contribute to flooding and carries pollutants that degrade water quality.

“Hundreds of miles of ditches criss-cross each watershed. While the ditches drain roads, they also efficiently intercept the runoff from adjacent hillslopes, capturing about 20 percent of the runoff in each watershed. Ditches rapidly shunt the water to streams, where it is discharged, like a high-velocity faucet. Ditches are also conduits of road salts, fertilizers, and viable pathogens from lawns and farms to streams. Unprotected ditches are a significant source of suspended sediment and gravel, turning the streams brown with each storm event. The ditch outputs disturb the natural stream flow and cause erosion along the stream banks.

“The end results of these cumulative impacts are: • increased flooding • declining groundwater tables

• drier streams and empty wells

• greater streambank erosion

• increased pollution in our drinking water supplies

(I would also add to this list that the ditching undermines the root systems of roadside trees, causing them to topple over and fall across roads, power and telephone lines)

“The management practices for roadside ditches, instituted nationwide almost a century ago, have been implemented in large part without considering the impacts on downstream water resources. Growing water scarcity and anticipated impacts from climate change, however, call for better water stewardship. We need to balance the value that ditches provide in protecting our roadways with the negative effects on our water.”

I realize that the ditches offer protection from some roads washing out and that probably includes the dirt road I live on. I think my local highway departments from Conesville and the town of Rennsalaerville do a fine job maintaining my road, but as these rainfall events become more and more catastrophic, we need to rethink or tweak some of the common practices that are being utilized. Any

time bare soil is exposed to heavy rain, the runoff will turn the creeks to mud. Vegetation in the ditches can reduce the mud effect dramatically.

I recall a simple demonstration that the Greene County Soil and Water Conservation District used to show sixth grade students at the annual Conservation Field Days Event at the Siuslaw forest in Acra. Two trays, each about 2 feet wide and 3 feet long, about 4 inches deep were prepared. One tray was filled with bare soil and the other contained grass sod, such as you can purchase for an instant lawn. The trays also had drainage holes drilled at the bottom, lower end of each tray and they were placed on an angled surface, simulating a hillside, slope. Water from a watering can was poured

equally on both trays until it ran out the drain holes. The water poured on the bare soil tray, exited the tray much faster (almost instantly) than the grass covered one. The bare soil tray run off water was also chocolate brown and muddy and soon resulted in half the soil in the tray being dissolved and washed away. Far more of the water was retained by the grassy tray, for much longer and when the water finally did run off, it was crystal clear.

This is a simple, yet dramatic, example of exactly what happens when bare soil is created by roadside ditching. At the very least, these ditches need to be seeded with quick growing grasses as soon as they are made. Please pass this on to any science school teachers that you may know!