Water, Water Everywhere, How Much is there to Drink?

All the water that ever was or will be on earth is here right now. More than 97% of the Earth’s water is within the in oceans. The remaining 2.8% is the water within the land masses. The land masses contain all the fresh water on the planet. Of the land surface water, 77% is contained in icecaps and glaciers and for all practical purposes is inaccessible in the short run. The remaining fresh water is stored primarily in the subsurface as ground water with a tiny fraction of a percent of water is stored as rivers and lakes.

The water on earth never rests, it is constantly moving within the hydrologic cycle along various complex pathways and over a wide variety of time scales. Water moves quickly through some pathways -rain falling in summer may return to the atmosphere in a matter of hours or days by evaporation. Water may travel through other pathways for years, decades, centuries, or more—the groundwater stored in the Wasia aquifer in Saudi Arabia fell from the atmosphere as rain thousands of years ago.

Water enters the atmosphere through evaporation and exits as precipitation -rain or snow. Typically, water remains in the atmosphere as vapor for about 10 days and it is this time that allows water to move from the oceans to the land mass. Then condenses and becomes rain, snow, or mist. The pattern of precipitation changes over time and causing or responding to changes in the climate of the planet. A falling raindrop might evaporate, or perhaps be taken up by a blade of grass or other plant. The rain drop might fall on the ground and form a puddle or run off across hard packed soil or pavement. This water will likely evaporate, infiltrate the soil or travel to a stream and ultimately flow to an ocean; at any point along this journey water can evaporate and start again. The average time for water to go from rain to stream flow to oceans ranges between 16 and 26 days. Mankind has interrupted the flow of streams and rivers to the oceans by diverting water for irrigation and building reservoirs, thus slowing or interrupting its flow to the ocean. http://pubs.usgs.gov/circ/2007/1308/pdf/C1308_508.pdf

Not all surface water flows to oceans. Some lakes and wetlands have no surface drainage. They lose water to evaporation and to groundwater. Water moves much more slowly in the subsurface than in the atmosphere or on land surface. Water that infiltrates the soil can remain in the unsaturated zone where it is returned to the atmosphere by evaporation or plant transpiration or the water it can discharge to the surface in a channel becoming surface flow; or it can begin the longer journey- traverse the unsaturated zone and recharge an underlying aquifer. The water that remains in the unsaturated zone typically remains in the subsurface less than a year. Infiltrated water that travels to the saturated zone, and becomes recharge for the aquifer spends much more time in the subsurface. The time that it takes for water to travel through the entire thickness of the unsaturated zone varies tremendously. It can take mere hours to travel through thin unsaturated zones in humid regions to millennia, for thick unsaturated zones in arid regions. The types of soil and rock, the amount of overburden and ground cover and the thickness of the unsaturated zone determines the travel time.

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 or fall far below demands during drought periods. Despite conservation the need for water continues to grow planet wide with the growth of human population and the development of emerging economies.

Groundwater Management in Virginia

The Virginia Ground Water Management Act of 1992 mandates the regulation of large groundwater withdrawals in certain portions of the Commonwealth to prevent adverse impacts due to over utilization of the resource. There are currently two proposed changes to the regulations. It has been proposed to expand the Eastern Virginia Ground Water Management Area to include the Counties of Caroline, King and Queen, Gloucester, Mathews, Middlesex, Essex, King George, Westmoreland, Richmond, Lancaster and Northumberland; parts of Spotsylvania, Stafford, Prince William, Fairfax and Arlington Counties; and the City of Alexandria. This would expand groundwater withdrawals beyond the confines of the Tidewater, west of the fall zone, into another groundwater basin. Currently, this Ground Water Management Area includes every county and city south of the York River and its tributaries and east of I 95, except Gloucester, Mathews, Middlesex Counties. The proposed expansion would bring these three counties on the edge of the Chesapeake Bay, and the corresponding area north of the York and its tributaries, into the regulated area. The boundaries of the Eastern Shore Ground Water Management Area would remain unchanged.

Ground water levels in the Tidewater region of Virginia’s coastal plain are continuing to decline. Impacts from groundwater withdrawals are propagating along the fall zone into the coastal plain and have the potential to interfere with wells in these areas. However, you cannot manage the several groundwater basins as if they were a single basin, but you cannot ignore the interrelation between the basins. The smallest of examples in this area is Bull Run which feeds the Occoquan Reservoir originates in the Piedmont. The coastal plain has been the area of the most intense growth and the area was forecast by Virginia Tech to have inadequate reserves to meet the next drought if not addressed. Given current ground water declines, the entire coastal plain aquifer system must be managed to maintain a sustainable future supply of ground water. Virginia is blessed with what appears to be rich resources of water, but they are not infinite. Surprisingly little hard data on the groundwater has been collected. As a much wiser man than I pointed out, without data there can be no understanding of our resources and our planet. What level of withdrawal does the Agency propose to allow in each basin?

The second proposed change is a little frightening because it both ambiguous and seemingly ambitious in its reach: the Board and DEQ propose “to consider amending the Ground Water Withdrawal Regulation, 9 VAC 25 610 to address the increasing demand on limited groundwater resources, changes to the administrative review process, and regulatory changes necessitated by new information on the coastal plain aquifer system.” Virginia is estimated to use 188 million gallons of groundwater each day to supply public water systems, industry, agriculture, commercial operations and mining. This excludes over 40 million gallons a day that supplies private domestic well in the state including my well. While applaud the agency’s proactive stance, to take action to manage and maintain our water resources before crisis strikes, I wonder how can the DEQ even propose regulations on diverse geology, demand and groundwater basins and do so without data. Though the goal is laudable, what methods are they proposing to manage, control, protect and allocate a resource that is not well understood? The agencies’ reasons for proposing this action echo and elaborate on their explanation of reasons for proposing to expand the Ground Water Management Area, but that is not enough.
Even more ominous, the Board is preparing “to address for which users and for what purposes this finite resource should be allocated” and “to address what constitutes an adequate margin of safety and what technical criteria are defensible for determining whether or not to issue a permit and for what amounts.” All of this appears to signal a readiness and desire to control the most valuable resource in the commonwealth of Virginia. Without water there can be no life, no economy. More importantly, the Agency seems to have determined that allocation of water resources will be performed by government with a strategy or manner of its choosing. The agency proposes to allocate the most valuable resource in the commonwealth of Virginia without answering the question of How should water be allocated. The Agency is determined to proceed to avoid ground water declines. Before the Agency proceeds to manage the groundwater use for Virginia, the people must determine how this resource should be managed.

California, What Are You Doing?

California’s natural hydrology is too limited to support growth in population, industry, and agriculture and possibly the current level of water use. Not only is California relative arid, but subject to, seasonal and climatic variability that threaten a reliable water supply. Approximately 70 percent of the State’s average annual rain and snow melt runoff occurs north of Sacramento, while about 75 percent of the State’s urban and agricultural water needs are to the south. Most of the State’s precipitation falls between October and April with half of it occurring December through February in average years. Yet, the peak demand for this water occurs in the summer months. Climatic variability includes dramatic deviations from average supply conditions by way of either droughts or flooding. California has dealt with the limitations resulting from its natural hydrology by developing an intricate system of reservoirs, canals, and pipelines under federal, State and local projects.

However, a significant portion of California’s water supply needs is also met by groundwater. Typically, groundwater supplies about 30 percent of California’s urban and agricultural uses. In dry years, groundwater use increases to about 40 percent statewide and 60% or more in some regions. California is mining its groundwater, using it at a rate higher than can be recharged. The groundwater in California may be a relic of the last ice age and is not being replaced or likely to be replaced under the current climate conditions.

For more than a half a century the Central Valley of California has been one of the most productive agriculture regions of the world. This has been made possible by the ample supply of water used for irrigation. On less than 1% of the total farmland in the U.S. the Central Valley produces 8% of the agricultural output (as measured by value). In 2002 this translated to $17 billion in crop value. This is all made possible by a combination of surface water diversions and groundwater pumping. Approximately one sixth of the irrigated land in the United States is in the Central Valley (Bureau of Reclamation, 1994) and approximately one eighth of all groundwater pumped in the United States is pumped in the Central Valley. It is possible that this irrigated agricultural model is not sustainable. California's current budget crisis have brought to the forefront the idea that federal taxes on the citizens of California support a disproportionate amount of the federal budget (an argument for smaller government). When will California realize that they have spent a sizable amount of their non-renewable water subsidizing the ranch landowners and cost of food in America.

When you withdraw the groundwater from fine-grained compressible confining beds of sediments and do not replace it, the land subsides. The incredibly fertile Central Valley was identified by the research efforts of Joseph Poland as the location of maximum subsidence in the United States. Once the land subsides, it looses its water holding capacity and will never recover as an aquifer. Groundwater mining in the Central Valley has slowed, at least until the recent water crisis. In 2007 the USGS estimated the rate of groundwater mining to be only 300 cubic feet per second. This change is due to the surface water agricultural deliveries of 13,000 cubic feet per second while groundwater irrigation deliveries are now (or at least were) at 5,900 cubic feet per second.Nonetheless, the clock is running. California’s non renewable water resource has been subsidizing the food budgets of America. California has been using up their water to produce cheap food for America and make ranch owners (the term for the mega farmers in California) richer. California is squandering its future and making decisions that almost certainly will require desalinization to support the population unless they recognize the true cost of water and make realistic decisions on its allocation.

Water Sustainability

Without water there can be no life. Water is our most valuable resource and how we manage its use or allow its abuse may determine the fate of mankind. The earth's total water supply is vast, estimated to be about 333 million cubic miles of water, over 96 % of which is saltwater. Fresh water represents only 4% of the total water of the earth. Over two thirds of the freshwater on earth (68%), is locked up in ice and glaciers, about 30% of freshwater is in the ground as groundwater, and thus, surface-water sources (such as rivers) only represent about 2% of the fresh water and 1/10,000th of 1% of total water, yet rivers are the source of most of the water people use. The interaction between surface water and groundwater is complex, site specific and not fully understood.

According to the US Geological Survey about 26 % of the freshwater used in the United States in 2000 came from ground-water sources; the other 74 % came from surface water. Groundwater is an important natural resource, especially in those parts of the country that don't have ample surface-water sources, such as the arid West. Groundwater is a renewable resource, but not in the way that sun light is. Groundwater recharges at various rates from precipitation and other sources of infiltration. The US Geological Survey estimated that the nation receives about a trillion gallons of recharge to the groundwater aquifers each day. (USGS circular 415). The recharge is not spread evenly across the nation or even where the water is needed.

There are costs and limits to the amount of groundwater available for extraction from the aquifer. Wells need to be drilled, pumps installed and operated and water moved through a delivery system. These represent the direct expenses of groundwater pumping. There are indirect costs. The amount of groundwater removed from an aquifer needs to be sustainable and should ideally match the recharge rate. Water captured by pumping a well will result in changes in the local or regional hydraulic balance- a reduction in discharge to surface water at some other location, 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. Changing the recharge rate by diverting water from the system can change the entire water balance and ecology of a region. Pulling large quantities of groundwater from one well rather than a series of smaller geographically spaced wells will have a much larger impact on the groundwater basin.

Groundwater availability and recharge rates vary locally and regionally and can be impacted by man. Over pumping of groundwater that results in compaction of the soils and subsidence which is permanent loss of water storage capacity in the region. Over pumping of groundwater in costal regions can lower groundwater tables or in a confined artesian system result in salt water intrusion. Development often is characterized by pavement and building that prevents the infiltration of precipitation that occurred before development. In some areas of the country (and world), groundwater currently being pumped entered the aquifer a millennia ago when the climate in that area was wetter. That water is not being replaced under these climate conditions and may ultimately be used up. Centralized wastewater systems further compound the problem by collecting the used groundwater, treating it and releasing the water into a stream or to the ocean in costal areas. Decentralized, managed and density controlled alternative onsite sewage systems may be a better solution for maintaining the groundwater resource, or as is done in areas of Florida and Long Island land application of the treated water from waste water systems.

Our freshwater resources need to be managed as a whole. The utilization of groundwater resources in an unsustainable manner can result in impacts to the entire region, including the decrease in water level and aquifer storage, reductions in stream flow and lake levels, loss of wetland and riparian ecosystems, land subsidence, saltwater intrusion and changes in groundwater quality. Each groundwater system or basin is unique and must be managed individually, and the data necessary to understand and manage water resources must be gathered locally over time to track and respond to changes in groundwater quantity and quality as well as stream flow. All groundwater is not equal and there a consequences of withdrawing water from an aquifer beyond its recharge rate. Water is critical to life and we need to manage this most valuable resource before our cities and western states run out.

The Geological Regions of Virginia

Loudoun County’s proposed amendments to the zoning ordinances that would create a Limestone Overlay District (LOD) got me thinking of about the geology of the state. I did not grow up in Virginia, but not only is my husband a native son of the Commonwealth, but he comes from a long line of teachers and I have sweet memories of a road trip with his Aunt Louise amusing her great nephew with teachable moments as we drove through the Valley, to the Blue Ridge, to the Piedmont. It was not until years later that I realized that Aunt Louise had been teaching her five year old great nephew (and me) the geological regions of Virginia.

The geological regions of Virginia are (from east to west) the Coastal Plain, the Piedmont, the Blue Ridge, the Valley and Ridge and the (Cumberland) Plateau. Historically, the geology of these regions has determined what the lands can be used for and by implication the nature of the communities that developed in these regions. Post World War II development of the suburbs had disconnected us from the direct ties to geology, but the density of the population and the demand for water, specifically groundwater is bringing us bank to understanding our geological destiny. The natural occurrence of groundwater depends on the geological conditions.

The Costal Plain of Virginia is composed mostly of unconsolidated geologic deposits and extends from the Atlantic coast to the “fall zone” a geological line that runs north-south through Fairfax, Fredericksburg, Richmond, and Petersburg. At its widest portion the Costal Plain is over 100 miles wide. Costal Plain deposits consist of alternating layers of unconsolidated sand, gravel, silt, shell strata and clay and slopes generally southeast. There are two groundwater systems, an unconfined aquifer and a lower artesian aquifer both flow in the general direction of the topography slope towards the ocean. In the 1990’s it was estimated that approximately half of Virginia’s groundwater use was in this region. The principal recharge area for these aquifers is the land around the fall zone where the aquifers outcrop. There is some leakage from the upper to the lower aquifer, but that is relatively insignificant. The Costal Plain’s artesian aquifer has an enormous groundwater storage capacity and Virginia remains a relatively wet location, but pumping (possibly over pumping) has lowered the artesian pressure allowing some salt water intrusion near the coast and overbuilding in the recharge zone has impacted the availability of water. It is projected with little more population growth that during drought years Fairfax and the Norfolk-Virginia Beach area will have inadequate water.

The Piedmont is bordered by the “fall zone” on the east and the Blue Ridge Mountains on the west. The Piedmont is the largest geological region in Virginia and has a diverse geology largely dominated by igneous and metamorphic rocks, with some areas of sedimentary rocks. The area has limited overburden and the fractures and fault lines formed in the rocks store and transmit groundwater. The size and number of water bearing fractures decrease with depth so significant supplies of water are generally located in the first few hundred feet. There is a wide variation in groundwater quality and yield ranging from under 1 gallon to over 50 gallons a minute. The largest yields are obtained where fracture and fault system are extensive (like my neighborhood) along the base of the Blue Ridge Mountains. In other areas of the Piedmont, disintegration of the granite bedrock forms a zone of granular material with slow recharge and relatively high and annoying amounts of iron and sulfur. The fractures and faults offer a route of transport for any contaminants so that the most water rich areas are the most susceptible to contamination.

The Blue Ridge province lies to the west of the Piedmont and is a narrow zone (4-25 miles wide) of mountains that runs from North Carolina to Maryland with the highest elevations in Virginia. The bedrock is near the surface and relatively impervious and contains limited amounts of water in joints, fractures and fault zones. Igneous and metamorphic rocks are most common on the eastern slope (and into the Piedmont) and sedimentary rocks are common on the western slope. Water yields are low and limited and typically very high in iron.

The Valley and Ridge region is to the west of the Blue Ridge Mountains and is underlain by consolidated sedimentary rocks of limestone, dolomite, shale and conglomerate. Limestone and dolomite occur beneath lowlands, such as the Shenandoah Valley (also within the lowlands between the Potomac and the Catoctin Mountains) these deposits consistently form productive aquifers. Karst features such as sinkholes, caves, and large springs are found in the Valley and Ridge province. The ridges in the upland area are typically underlain by sandstone and shale with limited groundwater yield. Limestone frequently contains underground channels that store and transmit groundwater. Rapid movement of water in the limestone area makes the pollution potential high. Aquifers are often recharged directly by streams crossing fault zones giving wells in these areas the highest yields. This direct surface water to groundwater recharge can create serious water quality problems. The groundwater in these zones bypasses any natural filtration the soil might have provided. The quality of the groundwater would reflect the quality of the seasonal streams and surface water.

The final and smallest geological region of Virginia is the Cumberland Plateau also called the Appalachian Plateau which includes the southwester tip of Virginia. This region is underlain by sedimentary rocks, primarily sandstone, shale and the coal. It is the presence of coal that has most determined the fate of this region. The gentle folding of these formations has created domes and basins and faulting has occurred. Groundwater quality is generally best in the bedrock above the stream level. The groundwater in the stream level contains high concentrations of sulfate, sulfite, nitrate, iron and carbon dioxide. The water improves at 150-300 feet below this area. Groundwater is generally used for small domestic purposes and processing coal. The shallow nature of the groundwater allows for relatively easy contamination.

Virginia is rich in water our actions will determine if we remain so. The process by which water from rainfall, snowmelt, streams and rivers flows into water bearing geologic formation is the groundwater recharge process. The climate change models (as limited and faulty as they may be) predict that Virginia will become a bit wetter and warmer (think North Carolina). A failure of the water supply in Virginia will be due to our own actions and decision. The land surface through which groundwater is recharged must remain open and uncontaminated to maintain the quality and quantity of groundwater of the Commonwealth of Virginia.

Groundwater the Fluid of Life

To survive over time, a population must live within the carrying capacity of its ecosystem, which represents a form of natural capital. One of the most important elements of the ecosystem is potable water. Without water there can be no life. As populations grow water is needed for drinking, bathing, to support irrigated agriculture and industry.

Unlike other natural resources or raw materials, groundwater is present throughout the world. Possibilities for its abstraction vary greatly from place to place, owing to rainfall conditions and the distribution of aquifers (rock and sand layers in whose pore spaces the groundwater sits). Generally, groundwater is renewed only during a part of each year through precipitation, but can be abstracted year-round. Provided that there is adequate replenishment, and that the source is protected from pollution, groundwater can be abstracted indefinitely.

Groundwater forms the invisible, subsurface part of the natural water cycle, in which evaporation, precipitation, seepage and discharge are the main components. The “visible” components are all strongly affected by weather and climate, and although they can be contaminated quickly, they generally recover quickly too. By contrast, the subsurface processes of groundwater are much slower and longer lasting, ranging from years to millennia. However, with careful management, these different timescales can be used to create an integrated system of water supply that is robust in the face of drought.

The groundwater cycle in humid and arid regions differ fundamentally from each other. In humid climates, with high rainfall, large volumes of water seep into the groundwater, which contributes actively to the water cycle feeding streams, springs and wetlands during periods when the rainfall is lower. In semi-arid and arid climates, there is by contrast practically no exchange between the surface water and groundwater because the small volume of seepage from the occasional rainfall only rarely penetrates the thick and dry (unsaturated) soils. The groundwater is much deeper and isolated from surface contact. In these areas groundwater resources are only minimally recharged. Our understanding of the complete water cycle is only rudimentary.

Any attempt to accurately model the groundwater component of the water cycle requires adequate measurements and observations over decades. The computer models in common use in the United States only address the shallower groundwater and surface water interactions; GSFLOW (USGS) and ArcHydro (ESRI) are two commonly used models. This has not yet been done, instead rules of thumb and common knowledge assumptions are utilized instead of facts. Robert Bisson of Earth Water Global believes that there is much more water below the Earth’s surface than commonly believed and that the majority of the earth’s water passes beneath the measured surface and groundwater zones undetected.

We do know that groundwater availability varies by location. Precipitation and soil type determines how much the shallower groundwater is recharged annually. However the volume of water that can be stored is controlled by the reservoir characteristics of the subsurface rocks. Groundwater may be present today even in places with very dry climates because of the nature of the local geology and the historic climate cycles that have occurred through time. In the north-eastern Sahara, the Nubian Sandstone Aquifer System underlies an area of more than 750,000 square miles in Chad, Egypt, Libya and Sudan, and contains huge amounts of fresh groundwater. Giant groundwater deposits of comparable size and limited recharge are thought to exist on nearly all continents, but the amount of groundwater that can be pumped out is unknown. Water resources can be used sustainably only if their volume and variation through time are understood. However such information is often lacking, even in so-called developed regions. Hydrology as a science is very young and so little is known. Is it possible that water in these arid regions is finite and non-renewable because of changes in the earth’s climate over the millenia? According to Victor Ponce of San Diego State University, deep percolation represents 2% of the precipitation in California. He believes that the shallow groundwater belongs to surface waters. Any pumping of shallow water (especially for irrigation) effectively shortcuts the natural process, returning to the land surface groundwater that was going to return to the surface waters anyway.

Groundwater is usually cleaner than surface water. Groundwater is typically protected against contamination from the surface by the soils and rock layers covering the aquifer. This is the only available clean drinking water in many parts of the world. However, rising world population, changes in land use and rapid industrialization increasingly place groundwater in jeopardy. Once contaminated, groundwater is very difficult to clean and often after removal of contaminated plumes only long term abandonment of use to allow for natural attenuation is the only possible course of action. As droughts and water shortages appear the value of groundwater has begun to be more fully appreciated. Precious groundwater resources increasingly need to be protected and well managed to allow for sustainable long-term use.

The demand for water is rising as population, economic activity and agricultural irrigation grow. However, worldwide resources of accessible water are decreasing, due to overuse or pollution. The balance between demand (consumption) and supply (resource) is becoming unstable. More than 30 countries suffer from serious chronic water shortage, and groundwater is increasingly being used to cover the demand. According to UNESCO Water for People between 700 and 800 billion US tons of ground water are pumped each year. This is two hundred times the annual consumption of oil and coal used each year.

California Water Wars

Friday night the California State Legislature ended its session for the year without taking any action in regards to the state’s water supply issues. There were a set of bills that reportedly would have both diverted water from the Sacramento San Pablo Delta and restored the habitat while potentially adding damns that would somehow add additional water along with the storage. The bills would also require a reduction of 20% in per capita urban water use and created a monitoring system for groundwater statewide. The legislation reportedly lost support of the Sierra Club, the Republicans and some other environmental groups. The fundamentals of the water supply system for California need to be addressed carefully and in a coordinated manner. The legislature has essentially chosen to continue the status quo which is unsustainable. The entire economy of California and possibly the United States will be impacted by the way in which California chooses to allocate water. Slapping another band-aid on the California water supply system is not how to address the complicated ecological, economic and human issues; nor is doing nothing. Cutbacks in surface irrigation water will results in increased pumping in the Central Valley which is nothing more than a geologic trough filled with sediments containing groundwater.

For more than a half a century the Central Valley of California has been one of the most productive agriculture regions of the world. This has been made possible by the ample supply of water used for irrigation. On less than 1% of the total farmland in the U.S. the Central Valley produces 8% of the agricultural output (as measured by value). In 2002 this translated to $17 billion in crop value. This is all made possible by a combination of surface water diversions and groundwater pumping. Approximately one sixth of the irrigated land in the United States is in the Central Valley (Bureau of Reclamation, 1994) and approximately one eighth of all groundwater pumped in the United States is pumped in the Central Valley.

According to the US Geological Survey the before the extensive development of irrigation of the Central Valley the natural recharge of groundwater from precipitation and surface water inflows equaled the outflows to evapotranspiration and surface water. After development of irrigation in the Central Valley the balance changed. Recharge to the groundwater was from irrigation return flow, precipitation and surface water inflow. Outflow was from groundwater withdrawals and increased surface water outflows. The net result was that the Central Valley, a 20,000 square mile area of California was mining groundwater at approximately 1,900 cubic feet per second from 1962 to 2003.

When you withdraw the groundwater from fine-grained compressible confining beds of sediments and do not replace it, the land subsides. The incredibly fertile Central Valley was identified by the research efforts of Joseph Poland as the location of maximum subsidence in the United States. Though the tremendous amount of subsidence was famously documented in 1977, it was not until 2003 that the water balance changed to slow the subsidence. In 2007 the USGS estimated the rate of groundwater mining to be 300 cubic feet per second. This change is due to the surface water agricultural deliveries of 13,000 cubic feet per second while groundwater irrigation deliveries are now (or at least were) at 5,900 cubic feet per second. When I was consulting, I saw vineyards and orchards in the Central Valley with groundwater irrigation wells. These vineyards were mortgaged. If the surface water allocation is reduced, how much groundwater are they going to pump? It is their livelihood, it is their investment, it is their way of life. Even if the surface water allocation to irrigation is not reduced the Central Valley is still mining groundwater that is not being recharged. The problems in the Delta estuary maybe more visible, but the long term viability of groundwater is our future.

Groundwater Use and Septic Recharge a Green Solution

It is a Common perception that Septic Systems are highly consumptive. However as studies by the USGS, North Carolina Division of Water Quality and the Dutchess County Water & Wastewater Authority have clearly shown, when designed for the correct densities and recharge rates, well (or even surface water) use combined with septic systems is highly sustainable and ecologically sound (Draper, 2006; USGS, 2002). Surface-water resources and groundwater treated in Septic onsite wastewater treatment systems are non-consumptive because they increase base flow into the watershed, and the water can be reused. Properly designed and managed traditional septic systems, alternative septic systems and clustered septic system are an effective method of waste disposal and trod lightly on the earth’s resources. According to the US EPA alternative septic systems, both single family and clustered, exceed the standards for sewage treatment plants and replenish existing groundwater systems, returning clean water to the earth’s water cycle. These alternative onsite systems can be more sustainable to the surrounding ecosystem than sewers and centralized waste treatment and are certainly less expensive for the homeowners in sparsely populated areas. However, the systems need to work properly and alternative systems with multiple tanks, compressors and various parts require consistent maintenance to continue working properly. Remember though, what goes into your septic system goes into the earth. Think carefully about the products you use to clean your house. Paint, solvents, gasoline, insecticides and poisons should never go down your drain. Every chemical you pour down your drain is buried in your yard. In a multitude of ways your yard is part of the earth’s yard.

The 2006 USGS study of water use and recharge in the Atlanta area (before the watering ban) found that average household indoor water use was 200 gallons per day and in the summer months the total water use increased to about 300 gallons per day including outdoor water use. Sustainability should be examined in light of that level of usage. The Dutchess County Water & Wastewater Authority commissioned a study by the Chazen Company at about the same time to better understand County-wide aquifer recharge rates and to provide guidance for setting sustainable development densities specifically related to the use of individual wells and conventional individual septic systems based upon average aquifer recharge. While the quantitative results of the study would apply to the soil types, rainfall and temperature ranges specific to the watershed studied, extrapolations can be made to nearby locations. The weather from New England to the Mid Atlantic to the South becomes warmer and wetter. Currently, average rainfall for New York is 39 inches per year while for Virginia it is more than 45 inches per year. The hydrologic soil groups present in New York are the same groups present in Virginia, but I would guess there is a higher concentration of C/D and D areas. The predominant area of the study, Wappinger Creek is C and C/D soil category. Chestnut Lick, a large creek, behind my house has similar soil hydrologic properties, but the soils on the acres surrounding the house contain a higher proportion of clay. This may be natural or due to the excavation associated with development of the lot and road.

Shallow groundwater flow, or groundwater runoff, intercepts the land surface, feeding springs, and creeks and seeping back into the surface waters as the perennial flow or streams, rivers and other freshwater bodies such as swamps, lakes and ponds. Deep groundwater flow also known as groundwater runout, does not intercept the land surface, flowing instead directly into the ocean. Of all the Earth’s water, only 3% is estimated to be freshwater. Groundwater is estimated to be more than 30% of the freshwater. Precipitation is the source of all groundwater, both shallow and deep. Hydrology is a young science and the modeling of the water cycle is not complete. The recharge rates and water cycle of the shallow groundwater in humid environments is much better modeled and understood than the deep earth sources of groundwater. So, while the entire water cycle is essential to man’s survival, only the shallow cycle will be discussed here.

Aquifer recharge consists of the portion of rain and snow (mostly rain in Virginia) that seeps through the soil to the saturated water zone, the aquifer. Another form of recharge is interflow which is infiltration water that flow along clay and bedrock layers, and roots to reach surface stream without entering the aquifer. Only the aquifer recharge supports wells and septic system dilution, while both recharge and interflow support the surface water supplies. In watersheds with high clay content in the soils a large portion of the rains is lost in runoff creating seasonal streams and high creek and river flow during the spring and fall rainy season. The average daily aquifer recharge (from rain and snow only excluding septic recycling) for Soils C, C/D and D in Prince William Virginia are estimated 326-583 gallons per acre. It is essential in a sustainable system that the groundwater level be maintained with recharge and adequate surface water is supplied to maintain the ecology even during drought years. My property totals more than 10 acres and our total indoor and outdoor household water usage was clocked during the early summer at between 100 and 150 gallons a day. We do not water our garden; trying to plant only what will thrive in the natural environment unaided. Virginia gets plenty of rainfall and it seems silly to plant anything that requires irrigation. Thus, not only is my septic system non-consumptive, the recharge rate vastly exceeds our water usage (and hopefully our neighbors since our water supply is dependent on total demand and recharge of the aquifer).

Though as demonstrated by the USGS studies, septic is a non-consumptive use of water, it is important that the septic system is designed and operated in a way that protects the environment. Whatever goes down the toilet or the drain goes into the earth. (See Septic Systems and the Ecologically Sustainable Life.)The Dutchess County report used nitrate concentrations at half the drinking water level as a proxy to achieve adequate dilution and natural attenuation of all contaminants. Historically, horizontal and vertical setbacks were developed without consideration of the dilution for wastewater components like nitrate, pharmaceutical residue, caffeine and other substances we humans consume, process or produce. The NY Department of Health separation distances were assumed (and these are almost identical to the Virginia setbacks), but the overall regional density of septic systems was examined to ensure that groundwater resources would not be overwhelmed by the total load of contaminants. The density recommendations were developed based on the nitrate concentration in traditional septic wastewater. Nitrate was used as a proxy because all humans produce about 10 pounds of nitrate per year, it does not easily break down and there is a drinking water standard. The target concentration was half the drinking water level to ensure all outcomes are safely below the standard since household size varies tremendously.

The Dutchess County study and the NC study found that overall average density of on-site waste disposal should not exceed one unit per 2-3 acres for an average size house to ensure water quality and recharge in groundwater supplies. The controlling factor in minimum lot size requirements in the northeast appears to be maintaining water quality, not groundwater recharge. Adequate dilution, soil filtration and time are necessary to ensure sustainable water quality. An interesting point is that it is not cost effective to install central water or waste disposal on parcels larger than about a half acre, since the cost of the piping (line connections) between parcels becomes much too high. Clustered or conservation subdivisions can be built, but need to maintain the overall density by maintaining open space. Those who live in dense population areas might want to look to the sustainable ideas of Adam Matthews and Siobhan O’Connor in Good magazine, the water issue, though, I find their idea of a composting toilet in any environment to be really scary from a public health perspective.