Though 71 % of the earth’s surface is covered in water (the oceans, the ice caps, the atmospheric water), it makes up only 0.025 percent of the mass of the planet — 25/100,000ths of Earth. Scientists believe that the water on Earth is somewhere between 4.3 to 4.5 billion years old, the most astonishing things about water is that all the water on Earth arrived here when Earth was formed, or shortly thereafter. “There is, in fact, no mechanism on Earth for creating or destroying large quantities of water. The water we have is what's been here, literally, forever…”
These facts are all from Charles Fishman’s book, The Big Thirst: The Secret Life and Turbulent Future of Water. It’s a good read; however, it does not clearly focus on the sustainability of our water supply. The need for water is constant it does not come and go with the weather. The need for water grows with population and wealth (though water demand in the United States has flattened out). While overall there is adequate fresh water in the United States, it is not available uniformly or when and where we need it. Water adequacy and sustainability is a local issue.
Water never rests entering the atmosphere through evaporation and exits as precipitation -rain or snow. Climate and weather patterns determine where it will snow or rain. Typically, water remains in the atmosphere as vapor for about 10 days allowing water molecules to move from the oceans to the land mass where it condenses -becoming rain, snow, or mist. The pattern of precipitation changes over time responding to changes in the climate of the planet.
Rain drops falls fall to earth and will evaporate, infiltrate into the soil, recharge groundwater or flow along the ground to a stream and ultimately flow into rivers and to the ocean-moving always moving. Mankind has interrupted the flow of streams and rivers to the oceans by diverting water for irrigation, withdrawing drinking water and building reservoirs, thus interrupting its flow to the ocean. We have also interrupted the recharge of groundwater. Changing the use of the land, covering it with buildings, driveways, roads, walkway and other impervious surfaces will change the hydrology of the site reducing groundwater recharge in the surrounding area. Once the hydrology is destroyed by development, it cannot be easily restored, if at all.
The available supply of fresh water is limited to that naturally renewed by the hydrologic cycle or artificially replenished by the activities of mankind. The recharge rate, the amount of natural replenishment, varies with weather and can exceed water demands during unusually wet periods like last year or fall far below demands during drought periods. A community or society becomes unstable if water resources are “used up” –groundwater used up, reservoirs pumped dry.
The Rural Crescent was created in 1998 and originally intended as an urban growth boundary for the county was designed to preserve the agricultural heritage and force redevelopment along the Route 1 corridor rather than development in the remaining rural areas. This was to be accomplished by limiting development to one home per 10 acres with no access to public sewers. To adequately judge the usefulness of the Rural Crescent the study must consider its impact on water resources and water ecology. While the Rural Crescent may have been the wrong policy to preserve our agricultural heritage, it has been a success at preserving water resources, protecting our groundwater and supporting the ecosystem of our region.
Preserving the Rural Crescent is essential to a sustainable Prince William County. The first half of sustainable development is the redevelopment of Brownfields along the Route 1 corridor rather than Greenfield development in rural areas where there is no existing infrastructure. Redevelopment along Route 1 would help Prince William County to improve storm water management as well as revitalize these older areas of the county. This redevelopment would take place without significantly increasing pavement and impervious surfaces. The second portion of sustainable development is to ensure adequate water for our county now and in the future.
The Rural Crescent is about water, specifically groundwater, though it also protects the Occoquan Watershed that is part of the primary supply of Fairfax Water. Residents within Rural Crescent rely on private wells for water and septic systems for wastewater disposal. Increased development can have an adverse impact on surrounding private wells and septic systems. There are limits to the amount of groundwater available for extraction from the aquifer. To be sustainable, the amount of groundwater removed from an aquifer match the recharge rate. Increasing the direct demand by pumping to supply water to commercial or residential users or reducing the recharge rate by diverting surface flow and adding pavement and roads will result in changes in the local or regional hydraulic balance- a reduction in discharge to surface water at, an increase in recharge from surface water, or a loss of storage in the aquifer by falling water table or some combination of these effects.
Prince William County is engaged in revising the sections of the Comprehensive Plan that pertain to the Rural Crescent. The details of the revisions being considered have not been finalized or released, but I am lead to believe that allowing significantly increased housing densities and clustered development within what is now the Rural Crescent is being considered. We need to study how any proposed land use change will impact water and groundwater sustainability for existing homes. The right of existing property owners to their water is primary and valuable and should not be compromised or impaired. Because there are natural fluctuations in groundwater levels it is easy to mask or ignore signs of the beginnings of destruction of the water resources that we depend on. Fluctuations in climate or rainfall and imperfect measurements and vantage points mask trends from clear view.
Changing the character of the Rural Crescent to include cluster development could impact water availability to the existing residents and impact base flow to our rivers. Bringing in public water and sewer connections even if they are limited to cluster development along what is being called the transition area, such expansion may exceed the capacity of the current systems and require water and sewer infrastructure expansion. Clustered properties cannot rely on well and septic- they are simply too close together, clustered development will be connected to public water supplied by Prince William Service Authority.
Currently, public water in the areas adjacent to the Rural Crescent is supplied by a combination of groundwater wells and surface water supply that is purchased from Fairfax Water and Lake Manassas. There is a cost to purchase additional capacity from Fairfax Water and that water is not unlimited. The viability of using groundwater wells to expand public supply from the Evergreen System is unknown. In addition, piping and pumps will have to carry water from its source to any new development. This would force the County to find additional sources of water at greater incremental cost to all ratepayers and such sources may not even be available. In addition, water mains and sewage piping are costly not only to build, but also to maintain.
For more than two centuries the waters of the Potomac seemed unlimited. It is not, Fairfax Water, Loudoun Water, WSSC, and the Washington Aqueduct all share the waters of the Potomac. The Interstate Commission on the Potomac River Basin, ICPRB, manages the Potomac River allocation of the regional water supply during times of low flow and plan for future water supply. The Washington DC region has reached the point in population density and development that during times of drought, natural flows on the Potomac are not always sufficient to allow water withdrawals by the utilities (including power generation which takes an awesome amount of water) while still maintaining a minimum flow in the river for sustaining aquatic resources.
Last winter the Virginia Legislature amended the comprehensive planning process (§§ 15.2-2223 and 15.2-2224 of the Code of Virginia ) to include planning for the continued availability, quality and sustainability of groundwater and surface water resources on a County level. State law now requires that the County plan to have good quality water for all its residents (present and future). Let's make sure that we carefully carry out that goal.
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