Mitigating Environmental Impact of Suburban Sprawl

Increasing suburban development and population density is a significant contributing factor to the impaired water resources in the Chesapeake Bay Watershed. Its impact is often hidden in the numbers because agricultural land represents almost twice the land as the developed areas. Growing populations in the suburban fringes of the Washington Metropolitan Area have had a significant impact on ecosystems in the region. Sprawling, low-density residential and commercial areas in the suburban and semi-rural areas result in additional infrastructure like roads (the controversial Bi-County Parkway) and shopping centers that chew up forests, green corridors, tree canopy, and agricultural lands. Often the remaining open areas between existing centers eventually fill with more new development. This type of development increases stormwater pollution and degrades the health of our water.

Image from Chesapeake Bay Foundation

According to the U. S. Environment al Protection Agency (EPA), the primary pollutants in the Chesapeake Bay and its tributaries are; nitrogen, phosphorus and sediment. These nutrients can lead to harmful algae blooms that kill underwater plants and destroy the river, bay and estuary habitat that aquatic life needs to survive. Excess nutrients and sediments can also lead to water with little or no dissolved oxygen to the detriment of aquatic life and the ecosystem. The Chesapeake Bay serves as a nursery ground for the fish and shellfish industry and protects the coast from storm surges and filters pollution. The estuary filters water that is carrying nutrients and contaminants from the surrounding watershed, protecting and restoring our drinking water supplies, the commercial oyster harvest and the beauty and ecological balance of the largest estuary in the United States.

EPA has legal authority to regulate point source releases of contaminants and pollutants- wastewater, industrial, and municipal separate stormwater systems (MS4), and concentrated animal feeding operation permits as well as set total maximum daily load (TMDL) of those contaminants in rivers and surface waters. The Chesapeake Bay pollution diet, the Total Maximum Daily Load (TMDL) of nitrogen, phosphorus and sediment was mandated by the EPA to the six Chesapeake Bay Watershed states (Virginia, Maryland, Delaware, New York, Pennsylvania and West Virginia) and the District of the Columbia.

EPA is invoking a “moderate levels of back stops” for Virginia under the Watershed Implementation Plan (WIP) for the TMDL to ensure adequate reduction in nutrient pollution to the Chesapeake Bay. This means that the WIP aggregate point source allocations for storm water and animal agriculture (CAFO) sectors were adjusted by the federal government to levels determined to be adequate to meet the TMDL. More stringent waste load allocations were applied to waste water treatment plants (regulated via federal programs); so that the waste stream from wastewater treatment plants was assigned to be 4 mg/L total nitrogen and 0.3 mg/L total phosphorus. For municipal separate storm sewer systems, MS4s, the federal government has imposed the requirement that 75% of urban MS4 lands meet aggressive performance standard through retrofit and redevelopment. I’m, quite frankly, not sure what that means in terms of installation and operation of storm systems, but the recent merger of the Virginia Department of Conservation and Recreation to have the Department of Environmental Quality (DEQ) be the lead agency for stormwater management is intended in part to address this.

In order to reduce the stormwater runoff carrying nitrogen, phosphorus, sediment and other pollutants from existing suburban residential areas stormwater best management practices (BMPs) will need to be implemented in the suburban communities. DNR, DEQ and the counties and cities of Virginia are going to have to implement non-point source nutrient management throughout the watershed. Homeowner Associations and individual homeowners need to individually and as a group reduce the nutrients and sediment run off from their properties.

Nutrient management and soil and water conservation districts (SWCDs) play a pivotal role in preventing such runoff in the agricultural community. In fact, SWCDs have been in the business of fighting erosion which prevents nutrient and sediment pollution since the mid-1930s, but agricultural operations are businesses that can see the direct result of maintaining their top soil and that have learned over the years to deal with various regulations. The challenge is much greater for the individual homeowner and the disperse sources of non-point source contamination; septic systems, poor drainage, impervious ground cover, lawn and plant fertilization, and household behaviors.

Virginia's 47 soil and water conservation districts have for years focused mainly on on-the-ground work implementing best management practices (BMPs) on farms. They have used the agricultural cost share program as the carrot to help foster the acceptance of BMPs and now have 100% funding available for their livestock exclusion program. DCR and the counties and conservation districts are attempting to develop strategies to reach out to not only farmers, but also urban and suburban landowners, and other land managers to encourage and help them to reduce their stormwater runoff and nutrient loads. Controlling runoff pollution is everyone's business and education and community have to be a large part of implementation. Each of us causes runoff pollution, and each of us must act to reduce its effects.

The difficult question is how does one educate the public of their responsibilities and then ensure that the public meets them? Suburban and semi-rural BMPs have the potential to significantly reduce nutrient and sediment pollution in the Chesapeake Bay, but DCR, DEQ and the Virginia Department of Health (VDH) have struggled to reach, educate and motivate the public. The VDH has set up an advisory committee of private sector septic design, maintenance and installation companies to assist in the transition to privatize the industry to the greatest extent possible and increase compliance with septic regulations by the public. Loudoun County has been in the forefront of innovative programs and to reach the public and appears to have successfully managed to privatize septic design, installation, maintenance and inspection within the county while utilizing their resources to track compliance.

Another area where Loudoun County is leading is experimenting with suburban BMP implementation programs. Loudoun County funded a pilot program with the county Soil and Water Conservation District to implement non-agricultural stream buffer plantings in several suburban developments. The Conservation district worked with county staff, the Department of Forestry, HOAs, individual homeowners, and all other stakeholders to plant canopy trees and under story plantings along stream banks to reduce erosion of the stream bank. The county provided funding for the pilot project at $7,000 per acre for a total of 10 acres the HOAs provided labor for the plantings and a covenant to maintain the plantings in perpetuity. The model of conservation districts working with suburban HOAs (especially the semi-rural developments) is one that could be copied and implemented broadly to include not only buffer plantings but infiltration trenches, bio-retention areas, rain gardens and curb cuts, dry swales and even septic maintenance best practices.