Land Use and Land Cover Changes Impact on Groundwater

Kumari Yadav S (2023) Land Cover Change and Its Impact on Groundwater Resources: Findings and Recommendations. Groundwater - New Advances and Challenges. IntechOpen. Available at: http://dx.doi.org/10.5772/intechopen.110311.

This is a book to read. The editor of the book cited above examined many of the  groundwater studies recently completed that assess the impact of Land Use and Land Cover (LULC) changes on groundwater. As you can imagine many of the impacts vary and there are tremendous gaps in our current knowledge. Below I have excerpted some of the introduction highlights. You can order a copy of the book from Amazon.

Groundwater is an essential. It serves as a buffer against short- and long-term fluctuations in surface water availability brought on by climatic variability. Approximately 2 billion people on earth depend primarily on groundwater for domestic and agricultural.  Groundwater is crucial for irrigated agriculture and for ensuring the safety of the world’s food security. Feeding mankind is the largest use of water. It accounts for 90% of freshwater consumption. The annual groundwater use for irrigation is 545 km³ of which 43% of the water used annually comes from groundwater.

In many areas, groundwater may be the sole supply of water that is always present. The use of groundwater is influenced by variables, including accessibility, transportability, cost-effectiveness, and availability. The main reasons why people choose to use groundwater water are reliable supplies and reasonable prices 

Groundwater recharge is the vertical flow of water that reaches the water table and increases groundwater storage. Rates of recharge vary by orders of magnitude over space and time, depending on the interaction of climate, soil, geology, surface hydrology, vegetation, and land use. Groundwater recharge, which occurs primarily through rainfall-recharge and surface water and groundwater interaction processes, replenishes groundwater aquifer systems. The change in LULC impacts groundwater recharge processes by modifying the earth’s hydrological system and balance.

Scientists are finding that the quantity, locations, and timing of groundwater recharge and discharge are increasingly altered due to rising population, agricultural growth, and urban land area. For groundwater development and sustainable groundwater resource management, groundwater recharge determines the groundwater withdrawal rates in a region

Land use change is a complex, dynamic process, which has direct impacts on soil, water, and the atmosphere. The most urgent problem of the twenty-first century in terms of groundwater monitoring and accurate projections is the rapidly changing Land Use and Land Cover (LULC). LULC change is becoming a major ecological concern influencing the groundwater recharge significantly. Understanding groundwater recharge in turn is necessary to determine what is a sustainable use rates and analyze aquifer sensitivity to pollution.

Groundwater quality is declining due to rising water demand, urbanization, changing land use and land cover, and climate change. Changes in LULC are among the most significant anthropogenic interventions.  LULC impacts the surface of the Earth by changing vegetation in forests, water bodies, and adding human structures.

While groundwater is an essential and significant portion of the freshwater supply for household, agricultural, and commercial applications, the effects of LULC change on groundwater recharge are not adequately understood, which leads to groundwater depletion. Therefore, understanding the impacts of LULC change on the groundwater is needed for the optimal management of natural resources.

Changes in land cover in the USA caused a rise in both the minimum and maximum temperatures. Additionally, groundwater condition (both quality and quantity) and its recharge are negatively impacted by urbanization of previous agricultural and open spaces. The hydrology of the region has been shown to have changed as a result of the conversion of natural, agricultural, and other low-population density sites into urban/suburban populations. Evidence shows that when urbanization is excessive, more than half of the precipitation drains off and just a small portion is infiltrated deeply.

The change in land cover has a significant impact on the change in groundwater recharge. Estimating groundwater recharge is crucial in managing water resources including surface water resources. It has become widely accepted that changes in LULC have an impact on groundwater. Numerous factors influence LULC change and its impact on recharge. Understanding of these processes and monitoring their impact is required to manage groundwater resources to be sustainable.

The Prince William County Board of Supervisors has once again issued a directive to staff for a groundwater study. The PW County Department of Public Works has submitted a proposal to the Prince William County Board of Supervisors for Groundwater Study to address concerns with the impact of future developments and the sustainability of groundwater as a water supply.

Last time the Department of Public Works proposed only to have the U.S. Geological Survey (USGS) create a Soil Water Balance Model and that it was not necessary or cost effective to study the actual groundwater in the various soil types in the county. This was not followed up on and was inadequate to assure sustainable water for all our residents.  Approximately 15% of Prince William County depend on groundwater for their drinking water. This includes the about 16,000 private wells in the semi rural areas of the county and the Evergreen Water District is supplied by groundwater wells.

We do know that groundwater availability varies by location even within Prince William County (Nelms and Richardson, 1990). Precipitation and soil types determines how much the shallower groundwater is recharged annually. The volume of water that can be stored is controlled by the reservoir characteristics of the subsurface rocks. We need monitoring wells spread in the areas of the county where groundwater is depended on in each of the soil types. In addition, we need the groundwater wells of commercial users to track usage. We need to ensure the sustainability of the groundwater in Prince William County. The water supply is not unlimited.

 

The Piedmont and Blue Ridge Groundwater

About half of the nation’s population relies on groundwater for drinking water. As the nation’s population grows, the need for high-quality drinking-water supplies becomes ever more urgent. The USGS has identified 68 principal aquifers in the United States, these are regionally extensive aquifers that are used as sources of drinking water.

Groundwater pumped from these primary aquifers provides nearly 50% of the nation’s drinking water. Twenty of these principal aquifers account for about three quarters of the nation’s groundwater pumped for public supply. These aquifers also provide 85 % of the groundwater pumped for domestic (private) supply. Three of these principal aquifers are in Virginia and were evaluated by the USGS National Water-Quality Assessment Project, which began in2012 and continued through 2021. Below are excerpts from the evaluation of the Piedmont and Blue Ridge aquifers and information taken from the USGS Groundwater Atlas of the United States.

The Piedmont and Blue Ridge crystalline-rock aquifers underlie an area with a population of more than 25 million people in 11 states (map). The Piedmont and Blue Ridge crystalline-rock aquifers, together with the other rock types in the Piedmont and Blue Ridge regions, rank second in the Nation as a source of groundwater for private domestic supply, providing about 360 million gallons per day (Arnold and others, 2017a).

These aquifers are also an important source of public supply, and about 92 million gallons per day are pumped for that use. Land use overlying the Piedmont and Blue Ridge crystalline-rock aquifers is mostly undeveloped (71 %) and agricultural (19 %). The cities of Atlanta, Georgia, and Charlotte, North Carolina, overlie the aquifers, as well as suburbs of Richmond, Virginia; Washington, D.C.; Baltimore, Maryland; and Philadelphia, Pennsylvania.

The Piedmont and Blue Ridge Provinces are underlain by three principal types of bedrock aquifers. In order of decreasing area, these are crystalline-rock and undifferentiated sedimentary-rock aquifers, aquifers in early Mesozoic basins, and carbonate-rock aquifers. Unconsolidated aquifers that are part of the surficial aquifer system overlie the bedrock aquifers locally in Pennsylvania and northern New Jersey.

Crystalline-Rock and Undifferentiated Sedimentary-Rock Aquifers are the most widespread aquifers in the Piedmont and Blue Ridge Provinces. These aquifers extend over about 49,000 square miles, or about 86 % of the area, of these provinces. Most of the rocks that make up crystalline-rock and undifferentiated sedimentary-rock aquifers are crystalline metamorphic and igneous rocks of many types. The main types of crystalline rocks are coarse-grained gneisses and schists of various mineral composition; however, fine-grained rocks, such as phyllite and metamorphosed volcanic rocks, are common in places.

Unconsolidated material called regolith overlies the crystalline-rock and undifferentiated sedimentary-rock aquifers almost everywhere. Because the regolith material varies greatly in thickness, composition, and grain size, its hydraulic properties also vary greatly. However, the regolith is more permeable than the underlying bedrock. Water in the bedrock is stored in and moves through fractures, which form the only effective porosity in the bedrock.

Early Mesozoic rift basins are spread out in the Piedmont Province and occupy about 9 % of the combined area of the Blue Ridge and the Piedmont Provinces. Aquifers in early Mesozoic basins are primarily in three major basins-the Newark Basin in New Jersey and Pennsylvania is the largest basin and the one from which the most ground water is withdrawn; second largest is the Gettysburg Basin of Pennsylvania and Maryland; and third is the Culpeper Basin of Virginia.

The Culpeper Basin of northern Virginia and Maryland is an elongate, fault-bounded trough that trends north-northeast from the southern border of Madison County, Va., about 90 miles to Frederick County, Md. All the formations in the basin are part of the Culpeper Group. The lower part of the group consists of sandstone, siltstone, and conglomerate of Late Triassic age; the upper part consists of Lower Jurassic sedimentary rocks and interbedded basaltic lava flows.

The water in the Culpeper Basin is the least impacted by iron, manganese and sulfate in the region and of only moderate hardness. My home overlies a section of the Culpeper basin that runs through all but one small corner of northwestern Prince William County. I chose this area for the water. It requires no treatment.

Carbonate-Rock supports the largest aquifers in the Piedmont and Blue Ridge. Limestone, dolomite, and marble of Paleozoic and Precambrian age form carbonate-rock aquifers that extend over about 3 % of the Piedmont and the Blue Ridge Provinces. Although these carbonate rocks are of small extent, they are significant local sources of water. Carbonate-rock aquifers are in five areas of the Piedmont and the Blue Ridge Provinces. In addition to these areas, small, isolated elongate stringers of limestone and marble form minor aquifers locally, particularly in Virginia, and generally trend parallel to the Blue Ridge front.

Recharge is highly variable in the Blue Ridge and the Piedmont Provinces because it is determined by local precipitation and runoff, which are highly variable and are influenced by topographic relief, ground cover, compaction and the capacity of the land surface to accept infiltrating water. 

Most of the Piedmont and the Blue Ridge Provinces are covered by regolith. Compared to the Blue Ridge, the gentler topographic relief of the Piedmont and less precipitation make the Piedmont less subject to rapid denudation than the Blue Ridge and thus favor the accumulation of a thicker regolith. The combination of large areas of thin regolith and dense bedrock with minimal permeability in the Blue Ridge Province do not favor large amounts of ground-water recharge. These areas have a limited ability to provide water.

Almost all recharge is from precipitation that enters the aquifers through the porous regolith. Much of the recharge water moves laterally through the regolith and discharges to a nearby stream or depression during or shortly after a storm or precipitation event. Some of the water, however, moves downward through the regolith until it reaches the bedrock where it enters fractures in crystalline rocks and sandstones or solution openings in carbonate rocks.

The USGS Aquifer Studies were designed to evaluate groundwater used for public supply prior to any treatment. Groundwater quality was assessed by comparing contaminant concentrations to regulatory limits established for drinking water quality.  Trace elements and major and minor ions are naturally present in the minerals of rocks, soils and sediments, and in the water that comes into contact with those materials.

The USGS sampled 60 wells at depths that a used for public supply wells: 150-700 feet beneath grade. Samples were analyzed for 90 VOCs, of which 38 have human-health benchmarks. VOCs were detected at moderate concentrations in 5 percent of the study area but were not detected at high concentrations. Compounds detected at moderate concentrations were the disinfection byproduct chloroform and the solvent trichloroethylene (TCE).

Manganese was found to be present at high concentrations relative to the SMCL in about 15 % of the study wells. Iron was present at high concentrations relative to the SMCL in about 12 % of the wells.

Samples were analyzed for 227 pesticide compounds (pesticides and their breakdown products), of which 119 have human-health benchmarks. Pesticides were not detected at high or moderate concentrations in the study

In some areas, the pH of the groundwater was not in the SMCL range of 6.5 to 8.5. The pH did not meet the standard in 35 % of the study area, typically because it was less than 6.5, which is acidic and potentially corrosive.

The total dissolved solids (TDS) concentration is a usually considered a measure of the salinity of the groundwater, though all water naturally contains TDS as a result of the weathering and dissolution of minerals in rocks and sediments. Concentrations of TDS can be high because of natural factors or as a result of human activities such as applications of road salt, fertilizers, or other chemicals to the land surface in urban or agricultural areas. Concentrations of TDS were high in about 3 % of the study area. Chloride, fluoride, and sulfate—constituents that also contribute to TDS concentrations—were detected at moderate, but elevated concentrations.

Radioactivity is the release of energy or energetic particles during spontaneous decay of unstable atoms. Most of the radioactivity in groundwater comes from the decay of isotopes of uranium and thorium that are naturally present in minerals in aquifer materials. Samples were analyzed for eight radioactive constituents, of which four have human-health limits for drinking water. The USGS found radioactive constituents were present at high levels in about 30 % of the study area and at moderate levels in about 17 %. Radon (using the proposed alternative maximum contaminant level of 4,000 picocuries per liter) and gross-alpha activity were the only constituents that were present at high concentrations. Radium (combined concentration of Ra-226 and Ra-228 isotopes) was detected at moderate concentrations in 2% of the study area.

Nutrients are naturally present at low concentrations in groundwater; high and moderate concentrations (relative to human-health benchmarks) generally result from human activities. Samples were analyzed for five nutrients, of which two have human health benchmarks. Common sources of nutrients, aside from soils, include fertilizer applied to crops and landscaping, seepage from septic systems, and human and animal waste. No nutrients were detected at high concentrations in the study area. Nitrate was detected at moderate concentrations in about 3% of the study area.

 

Bad Water – Test it to Know

Bad water is a term that has popped up several times in community meetings. It is vague, and could mean almost anything. Though neighbors have declared at community meetings that old-timers “all say the water is bad”, they refuse to spend any money to test their drinking water wells, opting, instead, to buy bottled water to drink. The water they are calling “bad” is from the northwestern portion of the Culpeper groundwater basin that provides water to all our wells, and happens in fact to be quite good source water. When I purchased my home, one of my contingencies was water quality. I had the right to exit the purchase if the water quality was unacceptable to me. Though the seller was willing to accept my vague contingency all we could negotiate was a 12 day contingency period and in reality I had less time than that. The power needed to be turned on to operate the water pump, the pressure tank drained and the water run to clear out the well and lines which had been unused for six months.

There are reasonably priced informational oriented analysis package available to the consumer; however, the turn-around time for these products is about 4 weeks and the analytical limits were higher than I wanted for this first analysis. I was interested in obtaining a water supply as pristine as possible, and I would refuse any traces of any industrial compounds. I was specifically looking for solvents, hydrocarbon fuels, heavy metals and pesticide traces that might have resulted from previous land use or difficult taste quality issues. I determined my best option to verify water quality within the transaction time frame appeared to be to use an US EPA certified laboratory to perform a rush compliance analysis of the water sample for every primary and secondary contaminants listed under the Safe Drinking Water Act while simultaneously researching the history of the land.

The good news is the results confirmed that the on-site drinking water well provided water that met the Safe Drinking Water Standards and was free of even trace industrial contaminants only having traces (parts per million) of naturally occurring minerals such as iron, barium, cooper and moderately hard water (the presence of calcium carbonate), but even these secondary criteria were below recommended levels. I concluded the groundwater supplying the house was uncontaminated from its previous use as a dairy/cattle operation and the water quality good. To obtain that analysis within the time frame of the contingency period I spent $1,635.00, not an amount of money I could spend again, but the house was the most expensive purchase of my life and I did not want to purchase a house with that ambiguous “bad” water. The water also tasted good to me. What I missed during the rush analysis and investigation of the site was the risks of the local geology. Coming from California I had not been familiar with the local geological variations.

Groundwater flows under ambient pressure from Bull Run Mountain towards Bull Run, the river. Thus, groundwater flows west to east. The soils in our neighborhood and the surrounding area are described by the USGS as Balls Bluff Siltstone with a gravel, sand and clay type bedding plane. (That is the technical name for the flat plane, edged orange red rocks that are everywhere you put a shovel.) In the siltstone bedding plane, the fractures within the rocks run predominately north south. Thus while ground water flows generally speaking west to east, water or a contaminant that catches a fracture will carry the contaminant to drinking water depth in a north south pattern. Contaminants can enter the groundwater at these fractures and zigzag through the neighborhood. Though the neighborhood is bound by rivers to the east and south which serve as hydraulic breaks within the neighborhood we are an enclosed fracture system with a potential of contamination from the north and west. There is no natural attenuation in a fractured system. Any malfunctioning septic system, improper disposal, mishandling of waste at the nearby horse farm or spill on any property has the potential to impact the drinking water well of other residents to the south, southeast or east. There is no guarantee that the water will remain uncontaminated so I need to monitor it regularly as well as keep an eye out for likely sources of contamination. I have continued to test my water well at least once a year using much more affordable options that are available.

The Prince William County Service Authority, PWSA, provides public drinking water to various communities in Prince William County through several public supply systems one of which is the Bull Run Mountain and Evergreen System supplying those communities, our nearest neighbors. The Bull Run Mountain and Evergreen Water System is supplied from eight deep-drilled rock wells located throughout the water system in the lower part of Bull Run Mountain south of us but also part of the northwest portion of the Culpeper Basin. The PWSA describes the groundwater in this area as rated as high for susceptibility to contamination. “These ground water sources are constructed in an area that tends to promote migration of contaminants with land use activities of concern…within a 1000-ft radius of the well site.” Like all public water supplies the Bull Run Mountain and Evergreen Water System is required under the Safe Drinking Water Act, SDWA, to test their water monthly for compliance. I review their reports to track the northwestern Culpeper Basin water quality.

Under the SDWA, the Environmental Protection Agency, EPA, sets standards for 91 contaminants in drinking water including bacteria and disinfection by products. For each of these contaminants, EPA sets a legal limit, called a maximum contaminant level. EPA requires that all public water supplies be tested for this list of contaminants on a regular basis and meet these minimum standards. In addition, EPA sets secondary standards for less hazardous substances based on aesthetic characteristics of taste, smell and appearance, which public water systems and states can choose to adopt or not. Though 91 contaminants is a lot, there are approximately 80,000 chemicals in use in our society and an uncounted number of pathogens and while monthly testing is required, only bacterial contamination is tested each month the other contaminants are tested over a longer time frame in the Bull Run Mountain and Evergreen System. Nonetheless, the water quality has remained consistently good during the past year.

Though a couple of the public supply wells are filtered for sediment removal, the PWSA states in their annual report of water quality. “We are proud to be one of the few Virginia community water systems that do not require disinfection treatment. The Bull Run Mountain and Evergreen Water System is Virginia’s largest non-chlorinated community water supply. We pride ourselves with having pristine natural source waters. Most wells are dosed with sodium hydroxide to raise the pH and reduce the water’s natural corrosiveness.” The public supply homes and businesses are receiving water directly from the groundwater source with a little sodium hydroxide added to neutralize it. That is a verification of the base water quality. My well draws from under 100 feet below grade and has consistently tested at neutral pH every year. I do not treat my water, when I examine the analysis each year I have seen no need for any treatment.

Routine testing has shown that the natural source waters in the northwest portion of the Culpeper Basin are pristine. The only way to know if your water is good water or bad water is to test it. Contamination from human and animal waste and chemicals can be real health hazards and should be addressed immediately. However, most of the water quality issues with private wells are from naturally occurring contamination or impurities. While many natural contaminants such as iron, sulfate, and manganese are not considered serious health hazards, they can give drinking water an unpleasant taste, odor, or color. Do not rely solely on water treatment salespeople for water analysis. The tests they perform are often crude and sometimes misleading. They are selling water treatment. The Virginia Household Water Quality Program subsidizes the analysis cost for private drinking water well clinics in a few counties each year. In 2012 Prince William, Loudoun, Frederic are among the counties that will have clinics. The analysis offered by the state program now includes: total coliform, E. Coli, sulfate, nitrate, fluoride, copper, lead, arsenic, hardness, total dissolved solids, pH, manganese, iron, sodium and is estimated to cost $55 for each household. Take the time to attend the clinic and test your water. You can save $100-$200 and get free help in interpreting the results. Join us and know the quality of your water.

Who will Control your Water

Fresh water supply poses a real and looming environmental risk. Regional shortages of water will drive decisions that will impact our future.

According to the US Census Bureau there are 312 million people in the United States. The water that exists on the planet is finite, but always moving as part of the water cycle or hydrologic cycle, on, above, and below the surface of the Earth. The good news about water is that “on average” the United States uses less than 8% of the water that falls as precipitation within our borders annually. Unfortunately, precipitation varies from that average significantly on a regional basis and over time, and our need for water is often greatest where there is the least precipitation because of the need for irrigation. In addition, only the cities on the great lakes have adequate precipitation and water storage to supply their population’s water needs, so our urban center have become very used to thinking of appropriating water from nearby regions to the cities.

As population rises, the demand for fresh water for drinking, domestic use, for industry (especially power generation) and for agriculture increases. The demand for food and the water that is essential to produce food grows with population and wealth. Globally, farming is estimated to account for 60% -70% of fresh water use. Irrigated agricultural consumes over 75% of the water in California, which produces 17.6 % of U.S. crops, and 7 % of the U.S. livestock and livestock products. California produces about half of U.S. grown fruits, nuts, and vegetables. Several of these crops are currently produced only in California. In the United States we have used the various complicated, layered and hidden subsidies within the various “farm bills” and subsidized water to complicate the business of farming and obscure the true costs of food in America.

This past spring, even as the Mississippi River basin was inundated with water, large portions of the arid west were struggling with drought. Farmers in the west pumped groundwater (unsustainably) to produce their crops. Regional water supply and allocation of that water is a growing problem especially in the western states which are arid, dependent on irrigation and have multi-state water right compacts. One of the best known of these Compacts is the 1922 Colorado River Compact, negotiated by the seven basin states (Colorado, Nevada, Utah, New Mexico, Wyoming, Arizona, California, ) divided the Colorado River basin into upper and lower portions, allotted consumptive use of the Colorado’s water on the basis of territory rather than prior appropriation. Before this agreement was negotiated allocation of water rights (ownership) was based on historic use, first to use the water owned it in perpetuity. In a land where water was wealth and all water was diverted from its natural location, this was how it was done. The allocation of water rights based on territory allowed development to proceed in the lower basin (essentially California) while safeguarding supplies for the upper basin. Then, as now, California's growth and demand for water was viewed with concern by her neighbors.

The problem is that the allocations promised were more than 100% of the water available and the demand for water has exceeded the supply. Specifically, the amount of water allocated under the Colorado Compact was based on an expectation that the river's average flow was 16.4 million acre feet per year. Subsequent tree ring studies, however, have concluded that the long-term average water flow of the Colorado is significantly less. According to the University of Arizona, a better estimate would have been 13.2 million acre feet at the time of the Colorado Compact and the records going back to paleolithic times (more than 10,000 years ago) indicates periods of mega-droughts in the distant past. During the drought of 2001-2006 the Colorado River flow was estimated at 11 million acre feet and hit a low of 6 million acre feet in 2002. The situation was critical bordering on regional rationing when the drought ended. More than 23 million people of the lower basin are at least partially dependent upon the water resources of the Colorado River. Almost 74% of them reside in the greater Los Angeles and San Diego areas. The deep snow pact and rain of last winter in northern California has taken has taken emergency rationing off the table- until the next drought.

Population growth, increased food production and increased power production all consume more and more water. The water available from the Colorado River has not increased with the increased demand and may even be falling. Even without climate change, paleoclimate records show a history of tremendous droughts in the region, and now more than 35 million people (in the upper and lower basins) depend upon the Colorado River’s waters for their water supply. The need for water is always growing. California is the most populous state in the nation and Nevada was identified as the fastest-growing state in the country in the 2010 census growing over 35% since 2000. Despite aggressive conservation activities the region simply does not have enough water to meet the projected demand. Las Vegas, was in the midst of a building boom when the drought hit. While adding 400,000 people they were able to reduce water use by a third by the implementation of draconian conservation measures. This was city and suburban consumption, not agricultural or power generation use of water which is much more difficult to cut.

The states of the Colorado Compact need more water. Overuse is killing the Colorado water basin which suffers from decimated aquatic ecosystems, overdrawn and irreparably damaged groundwater aquifers, and polluted agricultural and urban runoff. California has focused all its attention on developing a plan for reducing carbon dioxide emissions which is unlikely to prevent climate change, but they have failed to develop a workable water budget (or a balanced state budget for that matter). For two decades the Pacific Institute has called for a revamp of river management to protect endangered fish species and critical ecosystem elements, free up water for restoration of the Colorado River delta, and eliminate long-term groundwater overdraft throughout the basin. California and the other Colorado Compact states could not face the simple fact of a limited water supply and ignored the warnings, preferring to think about that tomorrow.

Even the conservation measures implemented in Las Vegas and throughout the region are not enough to ensure the long term water supply. The Southern Nevada Water Authority has requested to build a pipeline to transfer 65 billion gallons of water from northern Nevada to Las Vegas. The state will decide in January whether to proceed with that plan. The project has encountered stiff opposition from conservationists and rural communities against tapping northern groundwater to fuel more growth in southern Nevada. The pressure to push the project forward is off after the large snow pact of last winter inundated the area in the spring thaw and filled Lake Mead for the first time in a decade. Lake Meade sits on the Nevada-Arizona border and was formed in 1935 after the construction of Hoover Dam. Lake Mead and the upstream Lake Powell are the major water storage facilities in the Colorado Compact system. Roughly 96% of Lake Mead's water comes from melted snow in the upper Colorado River basin states: Colorado, Utah, New Mexico and Wyoming.

Las Vegas is only one small area of the Colorado Compact. Regional politics demands maintaining a vibrant agricultural sector, quenching the thirst of growing urban and suburban, growing economies that also demand water for power and industry, despite the limitations of the water supply. Politicians do not seem able to make the hard choices that will balance their water budgets. Instead the politicians came up with the idea to investigate the “Long-Term Augmentation of the Water Supply of the Colorado River System.” The study commissioned by the Colorado Compact states and the federal government identified 12 long-term augmentation options: desalination of both brackish water and ocean water, coalbed methane produced water, recharging groundwater from other surface sources, reduction of consumptive use of water for power generation, reservoir evaporation reduction, storm water storage, vegetation management, importing water via boat, water reuse, weather modification, and importation of water from the Midwest. Former Governor of New Mexico, Bill Richardson suggested “compacts” with the great lake states to import water to the drier western states under a federal water Czar. One of the ideas explored by the Southern Nevada Water Authority is to pipe 1,000 cubic feet of water per second from the Mississippi River 1,000 miles west to the Colorado River. They estimated that this aqueduct-pipeline would cost $11.4 billion to construct and an unknown amount of money to operate and maintain. Pat Mulroy, general manager of the Southern Nevada Water Authority, who is responsible for ensuring that the 2 million residents of Las Vegas have water argues that this plan could flood proof the Mississippi River Basin while recharging the depleted Ogallala Aquifer under the Great Plains and maintain and increase agriculture on the eastern side of the Colorado River. The plan is to remake nature with a modern era of big infrastructure projects rather than accept the limits of nature and locating large water use projects where water is plentiful. Water control and allocation would be another federal power under this water augmentation plan.

Protect the Rural Crescent Protect Our Future

The Rural Crescent in Prince William County is an urban growth boundary for the county that is intended to preserve our agricultural heritage and sense of place as well as achieve the goals of favoring redevelopment along the Route 1 corridor rather than Greenfield development in rural areas where there is no development. However, while I strongly support redevelopment of areas with preexisting infrastructure which would allow Prince William County to improve storm water management (and score nutrient points for the EPA mandated TMDL) as well as revitalize older areas of the county and preserve the greenfields areas in my general support of sustainable development; the Rural Crescent is about water, specifically groundwater.

The Rural Crescent in Prince William aligns roughly with the Culpeper groundwater basin, one of the more important watersheds in Virginia. My home and much of the Prince William County Rural Crescent is located within the northeast quadrant and eastern quadrant of the Culpeper basin and consists of an interbedded sequence of sedimentary and basaltic rocks formed about 200 million years ago. These volcanic rocks are intersected by diabase intrusives and thermally metamorphosed rocks. The rocks of the Culpeper basin are highly fractured and overlain by a thin cover of overburden. The lack of overburden is a challenge to gardeners and limits natural protection to the aquifer. These sedimentary rocks are productive aquifers and feed not only the groundwater wells that provide drinking water to Manassas and other communities, but also feeds the tributaries to Bull Run and the Potomac.

Ground water flows under ambient pressure from Bull Run Mountain towards Bull Run generally west to east with a slight southern slant in the northeast quadrant. The soils in this area are described by the USGS as Balls Bluff Siltstone with a gravel, sand and clay type bedding plane. (That would be those flat plane, edged orange red rocks that are everywhere you put a shovel.) In the siltstone bedding plane, the fractures within the rock run predominately north south. Thus while ground water flows generally speaking west to east, water or a contaminant that catches a fracture will carry the contaminant to depth in a north south pattern. Contaminants can enter the groundwater at these fractures and zigzag through the aquifer, but these fractures also serve as recharge areas. Groundwater is usually cleaner than surface water and is typically protected against contamination from the surface by the soils and rock layers covering the aquifer, but there is inadequate overburden in much of the Rural Crescent. 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.

The fractured rock system that is so rich in water is also our weakness, there is no natural attenuation in a fractured system so that the groundwater as a drinking water resource can be easily destroyed without any real ability to recover. Any malfunctioning septic system, underground fuel storge tank, improper disposal, or hazardous spill on any property within this area has the potential to impact the drinking water wells to the south, southeast or east. Development of the Rural Crescent would introduce potential sources of contamination that could never (in our lifetimes) be remediated. In addition, development of the Rural Crescent threatens the water supply itself.

Generally, groundwater in the Culpeper Basin is renewed each year through precipitation. The water stored in the watershed can supply adequate water in wet years and droughts provided that there is adequate replenishment, the withdrawal of water is within the average recharge rate and that the source is protected from pollution. Properly managed and protected groundwater can be abstracted indefinitely. Groundwater recharge through precipitation requires adequate area for infiltration, control of sheet flow created by roads and paved areas, as well as protecting the most geologically favorable infiltration points. Precipitation flows over the ground as surface runoff. Not all runoff flows into rivers, much of it soaks into the ground as infiltration. Some water infiltrates deep into the ground and replenishes aquifers (saturated subsurface rock), which store huge amounts of freshwater for long periods of time. Some infiltration stays close to the land surface and can seep back into rivers, creeks, and ponds (and the ocean) as ground-water discharge, and some ground water finds openings in the land surface and emerges as freshwater springs.

Prince William has more than adequate water to supply the County even with significant growth in population and industry without rationing, but conservation and water management are necessary and protection of the groundwater recharge areas are essential to maintain the water supply. Most of Prince William County is within the Piedmont geologic region, the largest geological region in Virginia. The Piedmont is bordered by the “fall zone” on the east and the Blue Ridge Mountains on the west. Our little corner of the Piedmont 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 and recharged by rainfall through near surface. 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 along the base of the Blue Ridge Mountains and in the Rural Crescent area near Bull Run Mountain.

A small portion of Prince William County is located within the Costal Plain and should serve as a warning to us of what happens if you do not protect your watershed and its recharge. 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 along Route 95. 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. The fall zone was the area of recharge for the artesian aquifer, it was the geologic area where the earth folded and the lower mostly isolated artesian aquifer reached the surface and could be recharged with rainfall. By building Route 95 along the fall zone and developing the adjacent areas Virginia essentially paved over a significant portion of the recharge zone for the artesian groundwater aquifer.

The groundwater withdrawals of the Coastal Plain now total more than 130 million gallons a day. USGS monitoring wells in the region indicate that artesian water levels are falling at rates of roughly1.0 to 3.0 feet per year. The water level decline is the result of a decrease in the hydraulic pressure of the artesian aquifer. Hydraulic pressure falls because groundwater is lost from aquifer storage by withdrawals (pumping) and reduced recharge caused by development of the recharge zones. It is predicted by Frank W. Fletcher, Ph.D., P.G. that Fairfax and the Eastern Shore areas could run out of groundwater to meet the demand if appropriate groundwater management does not take place. Fortunately, to a large extent the Coastal Plain areas of Prince William County are provided drinking water from public supply that originates within the Culpeper Basin, but we need to protect our groundwater and the only way to ensure an adequate clean supply of water for Prince William County is to preserve the Rural Crescent from any further development. The land must remain open and unpaved to allow for adequate rainfall infiltration to recharge the groundwater and the area must be protected from potential sources of contamination. Protect the Rural Crescent to protect our future.

Backyard Chickens and the Chesapeake Bay Watershed

Comparing the small scale backyard raising of chickens to full scale agricultural operations as I did is not an appropriate or fair comparison because scale and density are important elements of their environmental impact. Nitrogen and phosphorus are essential nutrients of the growth of living organisms in our yards and in the Chesapeake Bay. However, excessive nitrogen and phosphorus degrade the water quality of our groundwater, surface water and the Chesapeake Bay-the entire water shed. As population density has increased in the watershed, the amount of nitrogen, phosphorus and sediment entering the bay has increased tremendously.

Each year, approaching 300 million pounds of nitrogen reaches the Chesapeake Bay. The majority of nitrogen pollution comes from sewage treatment plants, large-scale animal operations, agriculture, and air pollution from vehicle exhaust and power plants and other industrial sources. Other sources of nitrogen pollution include septic systems, runoff from roadways, development, residential and commercial lawn fertilizers, and small scale animal and agricultural sources (the keeping of horses, poultry, and other animals and growing vegetables in predominately suburban or exurban locations. Solutions to nitrogen pollution include upgrading sewage treatment plants, proper operation of septic systems, using nitrogen removal technologies on septic systems, and decreasing fertilizer applications to lawns and controlling suburban and exurban animal waste.

Over the past quarter century the excess nutrient contamination to the Chesapeake Bay has decreased in total, but the Bay’s waters remain seriously degraded and considerably short of attaining the 2010 water quality goals set forth in the Chesapeake 2000 agreement. As a result US EPA is developing a new federally mandated Total Maximum Daily Load (TMDL) plan to establish and apportion an allowable pollution budget among the states.

Over the past 25 years, nitrogen released to the Chesapeake Bay has fallen about 33% from agriculture, fallen about 40% from waste treatment plants, but increased about 15% from septic and mixed open use. During that same period of time phosphorus released into the Chesapeake Bay has fallen about 29% from agriculture, fallen about 65% from waste treatment plants and increased about 14% from septic and mixed open use. The population in the region has increased by more than 20% (including the urban core) during this time period.

According to the Delaware Department of Natural Resources and Environmental Control, the typical household generates 10-15 pounds of nitrogen per year and 1-2 pounds of phosphorus per year. According to a Maryland state study, each chicken generates approximately 0.41 lbs of Nitrogen per year and around 0.35 pounds of phosphorus per year. Thus, each household with 10 chickens would generate 4.1 pounds of nitrogen and 3.5 pounds of phosphorus per year. This is a significant increase in the nutrient load of a typical house hold, a more than three fold increase in phosphorus load and an increase of nitrogen load by more than 30%. This additional waste is delivered in an uncontrolled manner. The poor location of a chicken coop could potentially impact ground water and well heads both on and off site and should be subject to the same off sets as septic systems. In addition the nutrient load has to be addressed.

Dutchess County New York did a study to monitor the effectiveness of septic set backs and studied nitrate concentrations. They chose to use nitrate concentrations at half the drinking water level as a proxy for 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 and phosphorus. 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 concentrations. Nitrate was used as a proxy because all humans produce nitrate, 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 can vary tremendously. The Dutchess County study found that overall average density of on-site waste disposal should not exceed one unit per 2-3 acres for an average size household to ensure water quality.

Adequate dilution, soil filtration and time are necessary to ensure sustainable water quality. Unfortunately, by adding 10 chickens to a yard you have increased the nutrient load significantly, tripling the phosphorus and increasing the nitrogen by 30%. The geology of this area consists of an interbedded sequence of sedimentary and basaltic rocks. The rocks of the Culpeper basin are highly fractured and overlain by a thin cover of overburden. The lack of overburden limits natural protection to the aquifer. The sedimentary rocks create a productive aquifers, but allow contaminate to easily wash into the groundwater basin. Allowing backyard chickens represent a significant threat to the groundwater basin.

Chesapeake Bay Watershed and Backyard Chickens

On July 8th 2010 the Prince William Planning Commission held public hearings on a proposed change to the zoning and land use regulations within the county. Currently chickens and other farm animals are allowed on 2 acres or more of agricultural land, but only if there's no house on the land. If there's a house, the property is considered residential and chickens are not allowed. Though probably not intended this regulation serves to protect the groundwater of the county. The proposed change to the zoning law would allow up to 10 chickens, pigeons or doves, or 5 ducks, or 3 turkeys, geese or pea fowl, or one emu or ostrich, or some combination of those on 2 acres. The law would also require the birds to be kept in a fenced area, coop or cage at least 10 feet from the house on the property, and at least 15 feet from the property line. The Planning Commission has tabled the matter.

According to Rodale's All-New Encyclopedia of Organic Gardening, poultry manure (chicken in particular) is the richest animal manure in nitrogen (N), phosphoric acid (P) and potash (K). Chicken manure is considered "hot" and must be composted before adding it to the garden. Otherwise, it will burn any plants it comes in contact with. However, there is an even darker side to poultry manure. The main cause of the Chesapeake Bay's poor water quality and aquatic habitat loss is elevated levels of two of those nutrients, nitrogen and phosphorous. According to the Chesapeake Bay foundation, runoff from animal manure accounts for about one-quarter of the nitrogen and phosphorus pollution that feed "dead zones" downstream.

According to the Virginia Cooperative Extension, poultry yards, and enclosed holding areas are areas of concentrated and accumulated animal wastes. These areas can be a source of nitrate and bacteria contamination to groundwater. The impacts can be mitigated by utilization of farm best management practices (BMPs); however, backyard farmers are not often versed in appropriate waste management techniques. The potential for livestock and poultry operations to affect groundwater is greatest if located on Karst terrain or over sandy-textured permeable soils, or other susceptible groundwater basins.
According to the US Geological Survey (USGS), much of Prince William County, especially the northeastern portion is located within the Culpeper basin which is highly susceptible to contamination. This is the source of drinking water for all the private wells in the area and feeds the tributaries to Bull Run.

The geology of this area consists of an interbedded sequence of sedimentary and basaltic rocks. The rocks of the Culpeper basin are highly fractured and overlain by a thin cover of overburden (that would be soil). The lack of overburden is a challenge to gardens and limits natural protection to the aquifer. The sedimentary rocks create a productive aquifers, but allow contaminate to easily wash into the groundwater basin. Ground water flows under ambient pressure from Bull Run Mountain towards Bull Run, the river. The soils in this area are described by the USGS as Balls Bluff Siltstone with a gravel, sand and clay type bedding plane. (That is the technical name for the flat plane, edged orange red rocks that are everywhere you put a shovel.) In the siltstone bedding plane, the fractures within the rock run predominately north south. Thus while ground water flows generally speaking west to east, water or a contaminant that catches a fracture will carry the contaminant to drinking water depth in a north south pattern. Contaminants can enter the groundwater at these fractures and zigzag through the adjacent neighborhoods.

There are two risks that should be carefully considered by the Planning Commission when making this decision, potential contamination of the drinking water supply for the area and potential for contaminated runoff to impact the Chesapeake Bay. Runoff from animal manure accounts for about one-quarter of the nitrogen and phosphorus pollution that feed "dead zones" downstream. Over the past few years, as I have monitored my groundwater quality, I have watched the nitrogen levels in my neighborhood rise. Groundwater protection should be a major consideration in whether to allow poultry on all residential properties. As our area has become more suburban, density has increased, along with the utilization of groundwater for domestic purposes and the density of septic systems. Unless, they intend to regulate the micro poultry farms and require the implementation of and maintenance of BMPs to manage the waste the county Planning Commission should deny the request.

Rethinking Organic

Recently, I read “Organic Inc.” by Samuel Fromartz. The book did two things, first it allowed me to understand the origins of organic food and how the concept of organic food has evolved with the regulation of the market and industry. The insight Mr. Fromartz provided to the organic food industry and farming made me rethink my position on organic food. Though traditionally, before the government stepped in to regulate the market, organic foods were grown under natural conditions (without the use of inorganic fertilizers, pesticides, or herbicides; and either not processed, or processed without the use of additives). Now, under standards adopted by the U.S. Agriculture Dept. (USDA) in 2000 and fully effective in 2002, organic food is food grown, raised and processed without synthetic fertilizers and pesticides, and antibiotics may not be used in raising organic foods, in addition, the use of irradiation, biotechnology, and sewer-sludge fertilizer is also banned. Food whose ingredients are at least 95% organic by weight may carry the "USDA ORGANIC" label; products containing only organic ingredients are labeled 100% organic.

However, under the government regulations the word "organic" refers strictly to the way farmers grow and process agricultural products, such as fruits, vegetables, grains, dairy products and meat. Organic farming practices are designed to encourage soil and water conservation and reduce pollution. Farmers who grow organic produce and raise organic meat don't use conventional methods to fertilize, control weeds or prevent livestock disease. The USDA organic label means that the food was produced using organic methods sanctioned by the USDA. So far there has not been any hard evidence that organic food is more nutritious of better for you. Food health studies are exceedingly difficult to run long term. So to a large extent the health benefits of not eating fruits, vegetables and grains with pesticide residue and meat without antibiotics and feed grain or grass without pesticide residue has to be taken on faith.

In the past I have bought organic where I thought it mattered to protecting my family from exposure to chemicals. Like strawberries, lettuce, apples, vegetables especially root vegetables where the outside of the fruit and vegetable is eaten. Other than that, I tried to buy only American grown produce, vegetables, herbs, beans and grains (though occasionally I do buy a couple of bananas). In terms of meat, I purchase organic, grass fed and pastured beef, pork, lamb and free range chicken. We only eat wild caught fish. I started buying grass fed beef back in the day when I was doing environmental evaluations of farms, dairies and concentrated animal feed operations (CAFOs). I will not go into the highly gross details of that work that have resulted in me barely ever eating meat. However, my concerns for the animal welfare, mad cow disease, and environmental impact of CAFOs pushed me to buy my meat from the first sustainable farm I inspected. In addition grass fed beef (and other animals) is lower in saturated fat and better for you. This was confirmed by Marion Nestle, author of “What to Eat” and Professor of nutrition at NYU School of Public Health. I asked her at a lecture I attended and she said that grass fed beef was as low in saturated fat as chicken.

Organic crop land is less productive than conventional farm land. Organic farming also requires more labor to keep weeds down. The average corn crop yield per acre in organic farming is 17 percent lower than down in traditional farming. Results range between 5 percent for corn to 35 percent for rye. For potatoes, root vegetables and turnips, crop yields are on average 14 percent lower than in traditional farming. In various fruits the yield was reported to be around 20% per acre lower with organic. That reduction in yield is basically why organic food sells for a premium. This loss of yield is an expense of organic farming, though there is a cost savings in not utilizing chemicals and in having soil retain its fertility through organic techniques of crop rotation. The chemical pesticides add to the cost of the crops in conventional farming, and conventional farming requires more irrigation water than organic farming.

Not only does conventional farming utilize more water, but the pesticide runoff impacts both surface and groundwater. The true cost of water is not expressed in the irrigation water charges in many places and the cost of the pesticide impact to water is not yet known and only recently have we begun to think about that impact. These days I am buying American grown organic to do my tiny part to protect the health of the soil, surface and groundwaters at least in my “neighborhood.”

Septic Regulations and Protection of Public Health and Waters of the State

On September 28, 2009 the Virginia Department of Health published their proposed Alternative Onsite Septic System, AOSS, regulations for public comment. For single family homes the regulations require that these systems are installed with conservative horizontal set backs, are operated and maintained by a licensed operator, grab samples taken by a licensed operator at either once a year or every five years (there is an inconsistency in the proposed regulations) and analyzed by an EPA certified laboratory, and an operating manual and records need to be maintained on site.

While I think the sampling requirement which is expensive does not provide additional protection to the environment and the operating manual requirement is inappropriate, the operation and maintenance of the system by a qualified and trained individual is reasonable. (Whether that individual needs to be licensed by the Board for Waterworks and Wastewater Works Operators and Onsite Sewage System Professionals at the Department of Professional and Occupational Regulation (DPOR) as a professional operator is for another time.) The truth is people do not seem to be able take appropriate responsibility for their septic systems. One method to deal with this problem is to eliminate all but the most basic systems in the most geologically favorable locations (reduce percolation rate tolerances and design the systems as conservatively as possible). The other method is to regulate, control and track. Establish system performance and monitoring and maintenance requirements, establish a tracking system and operating permits for compliance monitoring, and establish fines and enforce the program as the current regulations propose. Some version of these proposed regulations will go into effect in the near future. So, Virginia has chosen the control and track approach.

Let’s look at how requiring operation and maintenance might protect public health and the environment. A real world example would be a geologically unfavorable groundwater rich location. The small development where I live is located within the northeast quadrant of the Culpeper basin in Prince William County. The soil (if you want to call it that) consists of an interbedded sequence of sedimentary and basaltic rocks created around 200 million years ago probably by volcanic action. The rocks of the Culpeper basin are highly fractured and overlain by a thin cover of overburden. The lack of overburden is a challenge to gardens and limits natural protection to the aquifer. The sedimentary rocks are highly productive aquifers, but also subject to fractures that allow contaminants to move swiftly and easily through the system and easily reach depth in the groundwater aquifer.

Groundwater flows under ambient pressure from Bull Run Mountain towards Bull Run, the river. Thus, groundwater flows west to east. The soils in our neighborhood are described by the USGS as Balls Bluff Siltstone with a gravel, sand and clay type bedding plane. (That is the technical name for the flat plane, edged orange red rocks that are everywhere you put a shovel.) In the siltstone bedding plane, the fractures within the rock run predominately north south. Thus while ground water flows generally speaking west to east, water or a contaminant that catches a fracture will carry the contaminant to drinking water depth in a north south pattern. Contaminants can enter the groundwater at these fractures and zigzag through the neighborhood. The neighborhood is bound to the south by a river and the area is bound to the east by a river. There are also natural ponds, a manmade pond, and seasonal creeks. The rivers serve as hydraulic breaks. There is no natural attenuation in a fractured system. Any malfunctioning septic system, improper disposal, or spill on any property has the potential to impact the drinking water well of other residents to the south, southeast or east.

The new alternative septic regulations would require me and all my neighbors to properly operate and maintain their septic systems. Hopefully, preventing the neighbor’s septic system from contaminating the drinking water wells in the neighborhood. (I already have a operation and maintenance contract and my septic alarms to an automatic dialer to the maintenance company and my e-mail.) A cracked septic tank, malfunctioning system, improper management of stables, dumping of chemicals down the drain or in the yard, all have the potential to impact large sections of the neighborhood and need to be diligently guarded against by all residents. The need to negotiate the best rates for AOSS contracts may offer the opportunity for the HOA to create a buying group and educate neighbors. This could serve to protect all our drinking water. That remains to be seen; in the meantime I will be testing my water twice a year.