December 2000

Clean Water: A Regional Asset That Needs Our Protection

We get up in the morning and hop into the shower. We brush our teeth at the bathroom sink. We go into the kitchen and fix a cup of coffee or tea. We put our dirty dishes into the dishwasher and our dirty clothes into the washing machine. We turn a handle, push a button or turn a dial and take it for granted that clean, fresh water will appear to help us get through our daily lives. We hardly ever think about where the water comes from or how it gets into our homes.

We who live and work in the Baltimore area are fortunate to have an excellent metropolitan water system, among the best in the United States. Our water system is indeed among our most important assets-a foundation for our state and regional economy and quality of life.

While generally good, our sources of drinking water have been heavily stressed by our urban and agricultural activities over the last several decades. We have had to work hard to protect these valuable drinking water sources. As urban growth continues into the future, we will need to work even harder to prevent degradation of our sources of drinking water and to improve its quality wherever possible.

Where does our drinking water come from?

More than two-thirds of the region's 2.5 million inhabitants get their water from Baltimore City's Liberty, Loch Raven and Prettyboy reservoirs. Do you live within the shaded portion of the adjacent map? If you do, you live in a reservoir watershed. The rain that falls on your yard may end up in one of those reservoirs, along with residue from lawn fertilizers and the herbicides and pesticides you use in your garden. What you and others do in and around your homes and communities ultimately affects the sources of drinking water for the entire region-including your own drinking water, even if your water comes from a well.

What are the threats to the quality of the water in our reservoirs?

The three major threats to our water quality are nutrient enrichment, hazardous waste and loss of storage capacity in our reservoirs.

An excess of phosphorus flows into the reservoir from fields and lawns, soil erosion, septic systems and animal waste. Although some phosphorus occurs naturally in the soil, fertilizers add even more water-soluble phosphorus to serve as a nutrient for plant growth and development. Excessive phosphorus in our reservoirs leads to an overgrowth of algae, which is difficult and expensive to treat. The resulting drinking water often has noxious odors and colors.

Hazardous waste, such as oil, pesticides, paints and toxic chemicals, can enter the water system through residential or industrial sources, or from accidental spills.

Reservoirs lose storage capacity because of silting and sedimentation. Soil erosion in the watershed hastens the process. Loss of storage capacity reduces the "residence time" of water in the reservoirs, which in turn reduces the natural capacity of the lakes to cleanse the water before treatment. It also reduces the amount of available water during droughts.

Filtration and treatment remove sediment and the majority of pollutants from our water, but our first priority should be protecting the water supply. Dr. Dan Okun of the University of North Carolina spoke about source water protection at a recent satellite teleconference of the American Water Works Association.

Dr. Okun pointed out that the purity of water wasn't perceived to be an issue until the mid-nineteenth century, when London was plagued by a series of cholera outbreaks. According to the prevailing wisdom, vapors from the Thames were responsible for health problems along the river. Dr. John Snow, physician to Queen Victoria, did some epidemiological sleuthing, and found that the majority of cholera cases were centered around one well in central London. Six years later, during another cholera outbreak, Dr. Snow determined that the death rate was nine times higher among people whose water was drawn from the Thames in mid-London than among those whose water came from a cleaner, upstream section of the Thames. The purity of the source water was definitively linked with human health.

By the early 20th century, filtration and chlorination were standard practices for treating water for public consumption. However, by the middle of the 20th century, synthetic organic chemicals began finding their way into source water. Some of these chemicals came from the agricultural and residential use of pesticides and herbicides, and others from industrial sources. Some of these chemicals turned out to be carcinogenic. Filtration and chlorination can't handle this kind of chemical load. The cost of effective treatment increases as the quality of the source water decreases. Source water protection must be an ongoing activity.

How can we protect our water supply?

Local government must understand how land use affects water quality. Urban and industrial runoff have become significant sources of water pollution. Impervious surface areas, such as paved roads and parking lots, contribute to runoff. Preserving open space and minimizing impervious areas will help control runoff. All six local jurisdictions participate in BMC's Reservoir Watershed Protection Program, along with the Maryland Departments of Agriculture, the Environment and Natural Resources.

Individuals need to be aware of how their choices affect water quality. Homeowners can apply conservation measures to lawn and garden projects to reduce the use of fertilizers and pesticides.

Homeowners can get an inexpensive soil test from the University of Maryland Cooperative Extension to help minimize runoff from over-fertilization. New lawns should be tested after grading but before seeding. Established lawns, landscape plants and perennial gardens may be tested every three years. Call 1-800-342-2507 to request a soil test kit and instructions.

Planting islands feature a mix of trees, shrubs and groundcovers to reduce lawnmowing, and the use of fertilizers, herbicides and pesticides. These islands provide year-round beauty and homes for birds and other wildlife. A variety of native trees and shrubs should be used in combination with long-blooming perennials and groundcovers.

Native and beneficial plants for this area include flowering perennials such as the Black-Eyed Susan, purple cornflower and wild columbine; trees such as the American holly, red maple and willow oak; and shrubs such as bayberry, highbush blueberry and red twig dogwood.

For information about reservoir watershed protection, contact Jack Anderson at 410-732-0500 ext. 1006, or at janderson@baltometro.org.

To learn more about lawn and garden care, contact the Maryland Cooperative Extension Home and Garden Information Center at 1-800-342-2507, or visit their website at http://www.hgic.umd.edu/.