Three Reasons to Reduce Lawn Runoff

Even though policies are in place to help control stormwater and storm drain discharge, runoff can still be a potential risk to human health, cause fishkills, and destroy habitat, partly because only the handful of properties developed since 2004 are mandated to reduce the volume of runoff that is generated.

The routine practices that reduce contaminants in stormwater – pesticide and fertilizer reduction, pooper-scooper and "don't feed the geese" laws – do nothing to reduce the amount of runoff from driveways, roofs, and other impervious surfaces.

The volume of runoff increases when fields are replaced by impervious surfaces by as much as sixteen times, according to Thomas Schueler of the Center for Watershed Protection. When streams start receiving more water than they are sized to handle, they enlarge by eroding. As banks collapse to accommodate the increase in stormwater, the heavier soil like sand drops out of the water column into the sediment. The finer silt and clay soils stay suspended and flow downstream to slow-moving water, like a lake or an estuary, where they settle into the sediment. These fine sediments become habitat for bacterial survival and growth, and are where nutrients and pollutants concentrate, until they are resuspended back into the water by storms.

Initially, erosion from developed areas was thought to be solely caused by the velocity or speed of the stormwater. Detention basins are designed to reduce the velocity of runoff. But streams have continued eroding in spite of detention basins, because detention basins do not decrease the the volume of runoff.

A second problem is that stormwater is inherently polluted with animal droppings, but unlike wastewater, stormwater is not financially feasible to treat because of its volume. According to Thomas Schueler of the the Center for Watershed Protection, one inches of rain produces almost 26,000 gallons of runoff from a one acre parking lot. A five-family home produces something less than 500 gallons a day in sewage.

For the past couple of decades it was anticipated that the huge numbers of bacteria in runoff when it rained was solely due to sewage leaking into storm drains, and most of the regulatory work was focused on ways to look for illicit interconnections. But unless the amount of raw sewage was huge, many times water quality has not significantly improved after leaks were fixed.

A 2010 study from California provides a reasonable explanation: the impact from animal droppings - mostly from yard wildlife, not pets – has been underestimated. They found that fecal bacteria are surviving and multiplying in biofilms along street gutters. Their samples of enteroccocus, which is also the bacteria used to test bathing beaches, were as high as two million colonies. Beaches close if the levels exceed 104.

Finally, the direction of the wind influences how runoff affects water quality at beaches near stormwater outfalls. Sustained winds will drive the direction of coastal currents towards or away from the shore. On days when prolonged onshore winds hold stormwater in the swimming area, bacteria levels are higher than when offshore winds blow stormwater out to sea.

Reducing the amount of stormwater that a community collectively creates by draining it into the ground would significantly manage these three problems. When you reduce the amount of runoff, you also reduce the amount of pollutants that are discharged, you reduce erosion, and you reduce the size of the stormwater plume coming out of the outfall, making it easier for waves and currents to break up and dilute the plume.

A Cheap and Easy Way to Reduce Residential Runoff

The 2004 Stormwater Regulations only require new, large construction projects in New Jersey to reduce stormwater volume. There is no mandate for a homeowner to build a Rain Garden, or install pervious pavers in the driveway, or to plant trees, or to use other Low Impact Development techniques. That would be expensive, and many people do not have the money to do this, so it is not likely to be mandated in the foreseeable future. It would be a hard sell because each individual will have to take responsibility for reducing the stormwater from their own property, just as everyone now has to collect and drag their recyclables out to the curb. According to the NJDEP, LID could be used to "reduce an existing water quantity issue" and be included by a town or county as a nonbinding "Optional Measure" in their Stormwater Pollution Prevention Plan, as per NJAC 7:14A-25.6(i) in the 2004 Stormwater Regulations, but it is not likely.

If your lawn has sandy soils that drain well and don't pool water after it rains, and if your property is graded so that rain flows away from your house, then there is an easy way for you to reduce some of the runoff from your property. It is called downspout disconnection, according to the report "Barnegat Bay LID" by Princeton Hydro. Instead of letting the rain gutters drain down the driveway to the storm drain, you can reroute them so that they drain onto your lawn, at a reasonable distance from the foundation, where the rain will seep into the ground instead of becoming runoff.

It's not as effective as building a Rain Garden or installing pervious pavers or other LID practices, but collectively, the reduction in runoff would still be significant. In 2008, the Monmouth County Office of Geographic Information Systems predicted that one inch of rain produces about 3 million gallons of runoff just from the roofs on buildings east of Route 71 in Spring Lake, Spring Lake Heights, and Sea Girt.

More Reasons: Climate Change and CSOs

The downpours expected from Climate Change, as well as the ones delivered by Hurricane Floyd in 1999 and Irene in 2011, are wakeup calls that reducing stormwater volume in developed areas needs to be part of a strategy to manage regional flooding.

This is why both the Federal Emergency Management Agency (FEMA) and the USEPA recognize LID as part of a state or local Stormwater Management Plan for flood control. Initially, for example, developed areas upstream of critical facilities, like hospitals and police and fire stations, could be prioritized for LID. FEMA recommends that organizations convene a Resilient Community Advisory Committee, using the ‘Green Team’ approach as useful template.

The Consortium for Climate Risk in the Urban Northeast (CCRUN) is working in Queens to see how parks and other open areas can be modified by "curb cuts" to infiltrate stormwater and reduce the size of plumes from Combined Sewer Overflows (CSOs). These urban stormwater systems are legally designed to intercept and dump untreated sewage and stormwater into estuaries when it rains to avoid blowing out sewer plants. From Perth Amboy north, there are about 200 CSOs in New Jersey, and about 450 in New York. The NY/NJ Baykeeper is among the first to sue for mandatory LID in cities to reduce the size of CSO plumes and their impact on downstream beaches and shellfish beds in counties like Monmouth.

RESOURCES

Brzozowski, Carol. Thursday, April 04, 2013. After Hurricane Sandy. Assessing the damage, planning for the future. Stormwater. http://www.stormh2o.com/SW/Articles/After_Hurricane_Sandy_21074.aspx

Center for Watershed Protection. http://www.cwp.org/

Drewes, Donna. Posted on May 15, 2013. 5 Tips for Leading Change from NJ Green Teams. Sustainable Jersey. Geraldine R. Dodge Foundation. http://blog.grdodge.org/2013/05/15/5-tips-for-leading-change-from-nj-green-teams/

Federal Emergency Management Agency. 3/1/2013. Integrating Hazard Mitigation Into Local Planning: Case Studies & Tools for Community Officials. http://www.fema.gov/library/viewRecord.do?id=7130

Mangiafico, S. Accessed 10/2/13. An Introduction to Low Impact Development2012 Envirothon Trainings. Rutgers Cooperative Extension. http://salem.njaes.rutgers.edu/nre/ppt/2012_mangiafico_low_impact_development_scripted.pdf

New Jersey Department of Environmental Protection. Clean Water NJ. http://www.cleanwaternj.org/faqs.html

NJDEP. Tier A Stormwater Guidance. Chapter 11- Additional Measures. http://www.state.nj.us/dep/stormwater/tier_A/pdf/Chapter%2011.pdf

NYNJ Baykeeper. Accessed 9/28/13. Stop Combined Sewer Overflows in NJ – 2013. http://nynjbaykeeper.org/stop-combined-sewer-overflows-in-nj-2013/

Princeton Hydro. Accessed 5/16/13. Barnegat Bay LID. A Guide To Low-Impact Development in the Barnegat Bay Watershed. Pinelands Preservation Alliance. http://www.pinelandsalliance.org/downloads/pinelandsalliance_816.pdf

Schueler, T.R. and H.K. Holland. 1994. The importance of imperviousness. Watershed Protection Techniques 1(3): 100-111. http://yosemite.epa.gov/R10/WATER.NSF/840a5de5d0a8d1418825650f00715a27/159859e0c556f1c988256b7f007525b9/$FILE/The%20Importance%20of%20Imperviousness.pdf

Sherer, Brett, J. Ronald Miner, James A. Moore, and John C. Buckhouse. 1992. Indicator Bacterial Survival in Stream Sediments. J. Environ. Qual. 21:591-595 (1992). http://lshs.tamu.edu/docs/lshs/end-notes/indicatorbacteriased-1261132319/indicatorbacteriased.pdf

Skinner, John F., John Kappeler, Joseph Guzman. June 30, 2010. Regrowth of Enterococci & Fecal Coliform in Biofilm. Stormwater. http://www.stormh2o.com/SW/Articles/Regrowth_of_Enterococci_Fecal_Coliform_in_Biofilm_11064.aspx