Solar Panels Buy Now or Wait

The answer to that question depends on where you live, your cost of electricity, the orientation of your roof, and if you have to borrow the money to install the solar panels. However, the economics of solar panels with just the federal tax credit now make sense even in locations like Prince William County Virginia where there are no rebates or other subsidies beyond the federal tax credit. Above is a comparison of the costs and benefits of my solar panels compared to what that system would cost today.

There are several components to the cost and return of a solar system. The first cost is the cost of the system. The market cost of solar panels and installation has been falling for years. When I signed the contract to purchase my roof mounted solar system in 2009 (though it was not installed until May 2010) the cost per kilowatt for the Sharp panels I bought was about $6,700 plus permits and installation. These days that cost is about $1,800. I could probably have the same system that cost me $58,540 installed for around $19,000.That reduction in price goes a long way to make solar a reasonable purchase. Back in 2009 I was able to obtain a state rebate of $12,000 which is no longer available in Virginia. I also used the 30% federal tax credit which is still available. The net cost of the solar system in 2010 after rebates and tax credits was $32,578 today it would be about $13,300 for the same 7.36 kilowatt system.

To calculate the return on a solar photovoltaic system you need to know how much power the solar panels actually make. Now this is really weird, but with three years of data my solar panels make more power than predicted by the PV Watts model and the maximum output exceeds their rated power production. Instead of the expected 9 megawatts of power each year my solar panels have produced an average of 10.8 megawatts each year. This “bonus” was a pleasant surprise. I do not know whether it is due to having a steep angle roof that faces dead-on south over-looking a 3 acre open field or if the sharp solar panels are more efficient than rated. The dry weather in the past year might also have contributed to the higher than anticipated power production. Nonetheless, my solar panels make more electricity than predicted and that production rate would translate into a 9% return on investment (before depreciation) for solar panels bought today. It is not a spectacular return, but respectable and would justify installing solar panels and helping to reduce the summer peak demand on the power grid.

Lifetime power produced by my panels

However, with only the power generated by solar panels my return would around 4% before depreciation. To take the risk of buying and installing the solar photovoltaic system a chance for additional return on my investment was necessary. Solar Renewable Energy Certificates or SREC are another incentive that was available to me in 2010, but is no longer available for Virginia residents.

A SREC is a credit for each megawatt hours of electricity that is produced (and used by me). SRECs have value only because some states have solar set asides from their Renewable Portfolio Standards, RPS, which require that a portion of energy produced by a utility be produced by renewable power. Utilities in those states buy SRECs from solar installation producers. It is a way for states to ensure that the upfront cost of solar power is recovered from utility companies (and ultimately from the rate paying consumers). Most states at this point require their utilities to buy SRECs only from residents of their own states creating a closed market where the prices typically start off high until supply responds to that price. Other states, like Virginia, have no current solar RPS requirement and their RPS is voluntary. There are a couple of states, like Pennsylvania allow their utilities to buy their RPS from any resident within the PJM regional transmission organization. The Pennsylvania SREC price collapsed in early 2011 due essentially to oversupply and a method of calculating the penalty fee, the Solar Alternative Compliance Payment, SACP. It is to be noted that my electricity provider, NOVEC, would buy my SRECs for $15 each which is exactly what they pay for other forms of renewable energy they buy.

Within the PJM, a regional electricity transmission organization in 13 eastern states and the District of Columbia, I can sell my SRECs to utilities in Pennsylvania and Washington, DC (because I registered my system before the market was closed to outside systems). I had my solar system certified by both Pennsylvania and Washington though at the time only Pennsylvania was a viable SREC market. Today the Pennsylvania market has collapsed and in Washington DC my SRECs are worth around $400 for the moment. It will not last, all SREC markets get overbuilt in response to a high SREC value, but Washington DC has significant land constraints limiting large commercial solar arrays. So the SREC market may remain viable for a couple of years, I hope so, but I am not depending on it.

I had the choice to sell my solar renewable energy credits by estimate on the spot market or I can shop for a long-term SREC contract. The discount for a long term contract is huge and I refused to allow the company to put a lean on my house. A second option was a “guaranteed” price contract. In that case the fine print indicates that if the market collapses I might not have a viable guarantor of the payments. I would be giving up the upside without a true guarantee of price. The value of SRECs will go up and down depending on the supply and demand as determined by the number of solar installations, states requiring RPS, and states allowing sale within the PJM regional transmission organizations. RPS requirements are currently set to increase over time, but regulations and markets change. SRECs in Pennsylvania have ranged from $200-$300 per megawatt hour in 2010 and then collapsed and fell to $13 as the market remained open and became hugely overbuilt. Washington DC is currently undersupplied to meet the mandate so the SRECS have passed $400 each. The market will respond (I only hope not too quickly or too much). There was a time that New Jersey SRECS topped $670, they fell to $65 and are currently $140.

So while it lasts, the revenue from the sale of SRECs is higher than the value of the electricity the solar panels make. Today’s pricing make the return on investment in a solar photovoltaic system simpler to calculate here in Prince William County. There are other locations where various rebates and incentives and higher electricity rates make the return rich enough to support a market in financing alternatives, but it takes time and some level of expertise to optimize the solar incentives markets. Also, the incentives need to be paid for with either tax dollars (Department of Energy loan guarantees, grants and other incentives) or higher electricity rates- the renewable energy to fulfill the RPS and solar carve outs costs more than energy produced from other sources and results in higher electricity rates.

Groundwater Drought in Western Prince William

USGS monitoring well 49V1

It seemed that all of last week we had rain here in western Prince William County, my garden blooms and I am getting my garden in shape. As I was considering planting three trees that would need to be watered until they became established, I checked the water level in the U.S. Geological Survey (USGS) groundwater monitoring well up the road and was shocked at the water level. The median groundwater level for May based on 39 years of data is 9 feet below grade. The monitoring well’s groundwater level had fallen to just about 14 feet below grade. This was the lowest level of groundwater recorded for that well during May over the entire 39 years of data that had been recorded. The USGS maintains a group of 20 groundwater monitoring wells in Virginia that measure groundwater conditions daily and can be viewed online. One of the Virginia wells, 49V1 is just up the road from me in the same groundwater basin and serves as the proxy of the condition of my well.

The water level in a well usually fluctuates naturally during the year. Groundwater levels tend to be highest in the early spring in response to winter snowmelt and spring rainfall when the groundwater is recharged. Groundwater levels begin to fall in May and typically continue to decline during summer as plants and trees use the available shallow groundwater to grow and streamflow draws water. Natural groundwater levels usually reach their lowest point in late September or October when fall rains begin to recharge the groundwater again, though the lowest level ever recorded at the monitoring well up the road was in July 2011 at 15.38 feet below land surface. If the groundwater level in May is already this low, I am very worried about July and the general health of the aquifer. The natural fluctuations of groundwater levels are most pronounced in shallower wells like mine that are the most susceptible to drought.

The USGS has been using long-term groundwater monitoring data, combined with groundwater models, to improve our understanding of the storage and flow of groundwater. Whenever you pump water from a well it has to be balanced by a loss of water from storage in the groundwater aquifer. Groundwater is recharged from rain and surface infiltration from things like septic. If too much water is pumped, water tables can drop in unconfined aquifer like the one here in the Piedmont region of Virginia. The growing population and the effects of recent droughts have made the need for an updated status on the availability of the groundwater necessary and the USGS has been expanding their groundwater studies nationally.  I called the USGS Virginia Water Science Center in Richmond, Virginia and spoke to David Nelms the groundwater specialist. I happen to catch him right after the Drought Taskforce Meeting and so he was able to give me a well-considered opinion of what might be causing the low groundwater levels.

Mr. Nelms confirmed that this is the lowest groundwater level recorded in this region in May in 39 years. Though the Virginia Department of Environmental Quality, DEQ, has listed the groundwater conditions for Northern Virginia (including Prince William County) as normal, according to the USGS there is a small area in the Piedmont that just did not get enough rain last fall and over the winter to overcome the soil moisture deficit from the drought of 2012. According to Mr. Nelms this area of the Piedmont did not catch enough rainfall during the rains last fall even with Hurricane Sandy passing through. Though the water levels in the past couple of years have fallen to levels lower than recorded over the previous 39 years, the USGS did not think that anything other than a lack of rainfall was causing the low water levels. Mr. Nelms noted that the seasonal variation in groundwater levels seemed to be more extreme in recent years, and that the ownership of the property where the monitoring well is located had changed hands and could indicate a change in use could have impacted the apparent static pumping level by increasing the cone of depression if for instance the well had been used for irrigation or a sprinkler system. The USGS was not aware of any change in water use. As Mr. Nelms pointed the water level needs to be watched because it impacts not only the wells in western Prince William (including the Evergreen public water supply system), but also the surface water tributaries to the public water supply systems drawing from the Occoquan Reservoir and the Potomac River. Potomac River flow was also low for this time of year. Data from the National Weather Service’s Middle Atlantic River Forecast Center shows that the Potomac basin upstream of Washington, D.C. had a precipitation total which for the year to date is 1.5 inches below normal. We need to keep an eye on the water level and rainfall this summer.

USGS Data for 49V1

The 17 Year Cicadas are About to Arrive in Virginia

Many people know periodical cicadas by the name "17-year locusts" or "13-year locusts", but they are not the locusts of biblical note, which are a type of migrating grasshopper. However, if you live in the area if this year’s emergence, when the 17 year cicadas arrive in the next several days it may indeed feel like a plague. In Virginia there are seventeen broods of the 17-year cicada and thirteen broods of the 13-year cicada. Every year they will emerge somewhere in the state, but this is one of the largest in this region and coincides with the emergence up though Connecticut.

Some counties in Virginia have several broods that impact all or part of the county. The 2004 emergence impacted Loudoun, Prince William, Fairfax and Fauquier all of which will be impacted by the Magicicada Brood II that is emerging this year. The 17 year periodical cicadas or Magicicada adults have black bodies, red eyes and orange wing veins, with a black "W" near the tips of the forewings. The annual Cicada or dog day cicada as it is also called are related to the periodical cicada and appear every summer during the long, hot dog days of July and August. These cicadas have two- to five-year life cycles, but their broods overlap and some appear every summer. That is not the Cicadas that are now emerging from the ground.

17 Year Periodical Cicadas

Right now mature nymphs are emerging from the soil and climbing onto nearby vegetation and other vertical surfaces. They then molt to the winged adult stage. The emergence is tightly synchronized, with most adults appearing within a few nights. Adult cicadas live for only two to four weeks. When the 17 year periodical cicadas emerge the density can be shocking and noisy. It is common to have tens to hundreds of thousands of periodical cicadas per acre, but there are records of up to a million and a half periodical cicadas. This is far beyond the density of most other cicada species and half of the cicadas are “singing.” Male cicadas sing quite loudly by vibrating membranes on the sides of their abdominal segment. Male songs and choruses are a courtship ritual to attract females for mating. The males’ choruses have been known to drive people to distraction-stay inside with the windows closed and if need be use a fan for white noise. After mating, females lay their eggs in narrow young twigs slicing into the wood and depositing up to 400 eggs in total for each female in 40 to 50 locations each.

It is the egg laying that does most of the damage associated with periodical cicadas. Cicada eggs remain in the twigs for six to ten weeks before hatching. The nymphs do not feed on the twigs. The newly hatched, ant-like nymphs fall to the ground where they burrow 6 to 18 inches underground to feed on roots. Mature trees and shrubs usually survive even dense emergences of cicadas without long term damage, but in the summer of a large emergence many deciduous trees turn brown due to the breakage and death of peripheral twigs caused by the females laying their eggs and the emergence of the nymphs. Nonetheless, only young trees are usually permanently damaged and that is because so much of these trees are small twigs and branches. Newly planted trees need to be protected from periodical cicadas. Newly planted trees can be covered with a fine netting to keep the cicadas from reaching the small tender twigs. Secure the netting around the trunk to stop them from climbing up into the tree.Fruit trees need to be protected from the cicadas if they are to fruit this year.

Apparently because of their long life cycles and the synchronization of their emergences, periodical cicadas do not have natural population control by predators, even though everything from birds to spiders to snakes to dogs eats them opportunistically when they do appear. The massive emergence is believed to overwhelm predators and most of the periodical cicadas survive to mate and reproduce. Which is the whole point of the emergence. Cicadas are not poisonous and do not have a stinger. Their survival and expansion strategy is based purely on numbers.

Tri-County Parkway Public Hearing

If you have strong feelings about the Tri-County Parkway or you simply care about road development you need to attend the VDOT public hearing in Northern Virginia on May 29, 2013, 6 PM. The meeting will be held at the VDOT District Office, Potomac Conference Center 4975 Alliance Drive, Suite 1N201 in Fairfax, VA 22030.

The hearing is intended to solicit public comments on the draft Six-Year Improvement Program that is being released by the Commonwealth Transportation Board (CTB) ) on May 15, 2013 in in VDOT’s Central Office Auditorium located at 1201 E Broad St., Richmond, VA, and will be available online at www.Virginiadot.org on May 15th after the meeting.

As a result of the transportation funding plan passed by the General Assembly and signed into law by Governor McDonnell this year, funding is available for highway, road and bridge projects as well as rail, transit, bicycle, pedestrian and other transportation projects. The projects planned for the next six fiscal years beginning July 1, 2013 will be finalized in the next 45 days.

CTB will hold four public hearings to solicit comments about these “essential” projects identified in the draft report. In addition, the tentative list of projects selected by the CTB for Transportation Alternatives Program funding will be available on May 15th . The CTB states that public comments will be considered before the CTB adopts its final program in June.

If you cannot attend the meeting , comments can be sent by mail or email. For VDOT projects, the mailing address is Programming Director, Virginia Department of Transportation, 1401 East Broad St., Richmond, VA 23219 or email six-yearprogram@vdot.virginia.gov.

Opposition to the planned route of the Tri-County Parkway is building on the county level. On May 2nd Delegate Hugo, Delegate Marshall and Supervisor Candland participated in a well attended community meeting organized by “Say No to the Tri-County Parkway” at Bull Run Middle School. Then during Citizen’s Time at the Prince William County Board of Supervisors regular meeting on May 7th  several people associated with "Say No to the Tri-County Parkway” spoke out against the planned route of the Tri-County Parkway and the closing of U.S. 29 and VA 234 through the Park and asked the supervisors to support the community group in their quest to stop the parkway.

Chairman Stewart while affirming the need for an outer beltway, pointed out that in 2005 the PWC Board of Supervisors passed a resolution in support of locating the Tri-County Parkway east of the Battlefield which would move it out of the Rural Crescent and away from the direct watershed of Bull Run. He stated that closing VA 234 and U.S. 29 through the park would be very disruptive of traffic and that the Board of Supervisors did not in any way support that plan.

On May 14th Congressman Frank Wolf sent a letter to the Governor that can be read at this link.

Two Scientists Claim Roundup Linked to Diseases of the Western Diet

In the news have been articles about a “report” that was published in the online journal Entropy. This report or paper was a rational scientific argument based on the systematic search of the literature and possible pathways of impact that led the authors to believe that many of the health problems that appear to be associated with a Western diet could be explained by biological disruptions that have already been attributed to glyphosate. These include digestive issues, obesity, autism, Alzheimer’s disease, depression, Parkinson’s disease, liver diseases, and cancer. The paper was authored by Stephanie Seneff, a researcher at the Computer Science and Artificial Intelligence Laboratory of MIT, and Anthony Samsel, a retired science consultant from Arthur D. Little, Inc. as well as a member of the Union of Concerned Scientists.

Glyphosate (N-phosphonomethylglycine), the active ingredient in the herbicide Roundup that is manufactured by Monsanto (though the formulation is no longer under patent) is according to the authors, the most popular herbicide in use today in the United States, and increasingly throughout the World. Today, Americans spray an estimated 180-185 million pounds of the weed killer, on their yards and farms every year. All the acute toxicity tests have indicated glyphosate is nearly nontoxic to mammals. The typical description (by services that want to spray it in my yard) is that you could drink a bucket of the stuff and be perfectly fine. Thus, any residues of glyphosate that are ingested from food sources are safe. As a consequence, measurement of its presence in food is practically nonexistent. Glyphosate and its metabolite aminomethylpholphonic acid (AMPA) have not been covered in the reports from the Center for Disease Control on Human Exposure to Environmental Chemicals, so human exposure has not been measured.

Nonetheless, there have been for some time a minority of scientists and experts who believes that glyphosate may instead be much more toxic than is claimed and Anthony Samsel and Stephanie Seneff have put together their paper to argue the case for reexamining potential impacts to human health from low level constant exposure to glyphosate and studying that exposure. In humans, only small amounts (~2%) of ingested glyphosate are metabolized to AMPA, and the rest enters the blood stream and is eliminated through the urine. The philosophy that tiny amounts of chemicals are of no health consequence has been the cornerstone of toxicology and regulation, but that has recently come into question with our increased ability to measure trace amounts of chemicals. For many environmental chemicals, more research is needed to determine whether exposure at the extremely low levels is a cause for health concern.

While correlation does not necessary imply causation, the authors develop the argument that the recent increase in digestive issues, obesity, autism, Alzheimer’s disease, depression, Parkinson’s disease, liver diseases, and cancer can be traced back to a combination of gut dysbiosis, impaired sulfate transport, and suppression of the activity of the various members of the cytochrome P450 (CYP) family of enzymes. In the literature study they found evidence that glyphosate disrupts gut bacteria and suppresses the CYP enzyme class.

As the authors point out the Western diet is a delivery system for glyphosate and other potentially toxic chemicals used in industrial agriculture. The diet they refer to consists primarily of processed foods based on corn, wheat, soy and sugar, consumed in high quantities. Chemical residues of insecticides, fungicides and herbicides like glyphosate contaminate the diet. In addition, since 2000 there has been widespread adoption in the U.S. of Roundup Ready® (RR) crops, for the production of soy, beet sugar, and corn. Confined animal feeding operations (CAFOs) are used to produce corn feed animals that produce meat that is vastly different from pasture raised, grass feed cows, pigs, sheep, goats, chickens. Now we are even feeding farm-raised fish corn. According to the authors the corn feed to these animals is laced with herbicide due to the late application of the herbicide. As a consequence, animal products like, eggs, butter, cheese and milk are also contaminated with these residues. The authors argue that glyphosate enhances the damaging effects of other food borne chemical residues and environmental toxins as well.

This paper is certainly food for thought, but without measurements of the presence of AMPA in human populations and further research there is only speculation. The authors do propose a pathway of impact to human health that should be investigated further. This paper was prepared (and peer reviewed) to be submitted to the U.S. EPA for consideration in the standard registration review they are conducting of glyphosate to determine if it’s use should be limited. The study is among many comments submitted to the EPA that is expected to complete their review by 2015. Monsanto and industry experts have submitted a review of their studies and believe that glyphosate has been proved safe to humans and the environment. As for me, I feel good about the “extra” money I spend buying organic grass fed meat and organic foods and all that extra time I spend cooking and preparing food. My personal decisions on  pesticides and herbicides is a blanket policy because my well draws from a shallow aquifer in a fractured rock system.

The proposed route of human impact of glyphosate from the article.

Samsel, A.; Seneff, S. Glyphosate’s Suppression of Cytochrome P450 Enzymes and Amino Acid Biosynthesis by the Gut Microbiome: Pathways to Modern Diseases. Entropy 2013, 15, 1416-1463

Tri-County Parkway to Destroy the Rural Crescent

From VDOT final report 2013

When the Deputy Secretary of Transportation, David Tyeryar, presented the scope of the planned crescent shaped North South Corridor, limited access cargo and truck highway, (the Tri-County Parkway) he glossed over a few key essential points. The Deputy Secretary pointed out the highway corridor is approximately 45 miles in length, and is essentially a more direct route for cargo and truck traffic connecting I-95 to Dulles Airport and Route 7. What he forgot to mention is that the North South Corridor portion alone will cost over $1,000,000,000, run through Prince William County’s Rural Crescent potentially damaging our watershed and impacting our groundwater resources, eliminates one of three corridors in our green infrastructure and once the segment of the Tri-County Parkway between I-66 and VA 234 is complete, U.S. 29 and VA 234 through the Park are planned to be closed.
                             

red is 6 lands and blue 4 lanes

As Supervisor Candland (whose Gainesville District will be bisected by the six lane highway) pointed out this plan is troubling on many levels. Supervisor Candland has concerns about the effect of the planned Tri-County Parkway and greater crescent shaped roadway will have on commuters, the environment and our community, but the Tri-County roadway was approved by the Prince William County Board of Supervisors two years ago. So, on the county level, it has been approved. Supervisor Candland was not in office at the time, but the Gainesville Supervisor at the time (John Stirrup) was one of two votes against the plan.

Last Monday, April 29, 2013, Delegate Tim Hugo (R-40th), along with State Senators Dick Black (R-13th), Richard Stuart (R-28th), Jill Vogel (R-27th), and Delegates Bob Marshall (R-13th) and Michael Webert (R-18th), have all come out against the planned Bi-County Parkway (the North-South Corridor). Delegate Hugo will be attending a community meeting tonight at Bull Run Middle School at 7 pm in the cafeteria. The meeting was organized by "Say No to the Tri-County Parkway." There is still an opportunity to impact the VDOT plans through our state legislature and also through allocation of Federal Transportation funds so also contact Congressman Frank Wolf, Senator Tim Kaine, and Senator Mark Warner with your concerns. You can go to the Piedmont Environmental Council action center to help you express your concerns to our elected officials.

As Delegate Hugo stated “this road will destroy the Rural Crescent, land that the Prince William Board of County Supervisors has pledged to protect.” This project threatens our water resources and green infrastructure. The Rural Crescent is located within the northeast quadrant and eastern quadrant of the Culpeper groundwater basin and consists of an interbedded sequence of sedimentary and basaltic that is highly fractured and overlain by a thin cover of overburden. Groundwater 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 there is limited if any natural attenuation in this type of geology and the aquifer could be polluted beyond our ability to remediate.

Why the Rural Crescent was formed is less important than understanding that the Rural Crescent provides a significant portion of our green infrastructure to our community. Green infrastructure connects the still intact habitat areas through a network of corridors that provide for wildlife movement and trails as well as pathways for pollinators. Maintaining intact, connected natural landscapes is essential for basic ecosystem and watershed preservation to ensure that there will always be clean air and water in Northern Virginia.

In building out the county and highway system Fairfax County overdeveloped eliminating much of the county’s green corridors and is now dependent to a large extent on the regional green infrastructure from neighboring Loudoun and Prince William Counties. These green corridors maintain a tree canopy and control runoff to prevent stream bank erosion and water quality impairments and maintain adequate water flows through groundwater and surface recharge. These green corridors are vital to ensuring safe water supplies, water recreation and the ecological integrity of the region.

The Northern Virginia Regional Commission (NVRC) has developed a Conservation Corridor Planning Project which is a regional effort to identify essential green infrastructure and help area governments to avoid the mistakes of the past and maintain the few remaining green corridors along the rivers and reservoirs in Fairfax and integrate green infrastructure planning into the future development planning of Prince William and Loudoun counties.

This roadway cuts through and destroys one of three priority conservation areas for the region. The conservation area begins at the Bull Run Mountains and heads east across Route 15 to Manassas covering the land between Route 50 and 29 to the confluence of the Occoquan River with Belmont Bay. This corridor is rich in water and environmental resources that ultimately deliver drinking water to over one million Northern Virginia residents. The Occoquan Reservoir, one of the country’s first water reclamation facilities where sewage treatment water is returned to provide water recreation. The western portion of the area is part of the Culpeper Basin Important Birding Area and the Culpeper Basin Groundwater Aquifer. Preventing water contamination and ensuring adequate groundwater recharge are vital to ensuring safe water supplies, recreation opportunities and the ecological integrity of the region.

If you want to protect Prince William County, go to Say No to the Tri-County Parkway's  meeting speak to Delegate Hugo and write to Congressman Frank Wolf, Senator Tim Kaine, and Senator Mark Warner.

Prince William County the Retirement Mecca that will Survive Climate Change

The climate of the earth is constantly changing. Scientific studies have indicated that over the past century the earth has warmed 1.3 degrees Fahrenheit. This warming is not particularly alarming in itself given our planetary history, but the speed of this temperature increase and the fact that the warming is projected to continue at an accelerated pace is worrisome. The planetary warming is forecast to cause sea levels to rise due to melting of sea ice in parts of the world, and changes in weather and patterns and precipitation. If carbon dioxide (CO2) concentrations in the atmosphere are the driving force in earth’s temperature that many scientists believe, then these trends are likely to continue. On a whole earth basis the climate models show at this point there is nothing that we can do to stop global warming and climate change.

As the concentrations of CO2 in the atmosphere increase, the warming produced by the greenhouse gas effect is strengthened. Computer modeling of the climate predicts that there will be feedbacks that significantly increase the impact from the increasing CO2. Even if the concentration of CO2 in the earth’s atmosphere were to stabilize at this level, the changes in the climate of the earth in response to the atmospheric CO2 levels would continue for hundreds of years. In reality, the global emissions of CO2 will not stabilize or decrease any time soon and will continue to rise for at least a generation. What is going to happen will happen, so we need to plan for change and make decisions for the next 30-50 years based on likely outcomes.

It is my plan to live for another 40 years. My relatives do pretty well and I am an optimist and a “real food” and exercise devotee. So when it came time to select a place to live in retirement, climate change was one of the factors taken into consideration- water availability, distance from the coast, elevation, along with proximity to family, medical service and an airport and several other factors. Now, I find myself in northwest Prince William County a place that the Washington Post recently described as becoming “a regional retirement mecca, a small-scale version of Florida on the outskirts of Washington.” I made my choices based to a large extent on general projections of climate released by various groups, not having the tools or resources to do much more.

Now, however, the Interstate Commission on the Potomac River Basin (ICPRB) has completed a study in water supply availability and the health of the Potomac Watershed for various climate scenarios. The focus of their study was the Potomac River, which supplies water to the Washington Aqueduct, Washington Suburban Sanitary Commission (WSSC), and Fairfax Water who all funded the study. The Potomac River supplies 78% of the regions drinking water and the water utilities of the region must plan for the future. In addition, there must be adequate flow of the Potomac below Little Falls to ensure that the balance of saline and fresh water for the health of the Chesapeake Bay estuary. So, on the water rate payer’s nickel I get to see what the future might look like here in in Prince William County.

The National Research Program of the U.S. Geological Survey (USGS) actually performed the study using six of the global climate models and three atmospheric CO2 scenarios to create 18 separate possible scenarios. The USGS then “downscaled” the 18 global climate predictions to the Potomac River basin and to other areas as part of a separate project on climate change being conducted by the Chesapeake Bay Program Office and the USGS’s Virginia Water Science Center (your tax dollars at work). In addition, the Chesapeake Bay Program’s Phase 5 Watershed Model was used to estimate the impact of changing temperatures and precipitation on Potomac basin stream flows.

The most advanced types of models currently being used to project future global climate are general circulation models (GCMs). A GCM is a numerical model which represents the important physical, chemical, and biological processes on the Earth’s surface, in the atmosphere, and/or in oceanic systems that affect climate. The USGS used models from the National Center for Atmospheric Research (USA), Norway, Australia, Russia and Japan as listed in the chart below.

From ICPRB publication

In addition, the three CO2 emissions scenarios were based on IPCC’s Climate Change 2007: Synthesis Report (IPCC, 2007c). The USGS used relatively low emissions (B1), medium emissions (A1B), and high emissions (A2) temperature forecasts for each model to create the 18 scenarios.

IPCC Climate Change 2007

There is tremendous uncertainty in projecting the future climate of the earth, especially at the regional scale. Though global climate models are continually being refined and improved, they do not capture complexity of the interrelations of earth’s land, water, and atmospheric systems that we do not yet fully understand. Local nuisances can be lost in the broad sweeps of mathematical modeling of a living system. Scientific confidence in global model projections is higher for temperature than for precipitation, higher for global scales rather than small regional scales, and higher for longer time frames than shorter ones. Nonetheless, with all those disclaimers, the USGS did get some predictions out of their 18 scenarios.

Though it is predicted by the climate models that precipitation will increase on a global scale, when dealing with only the Potomac River basin, the models differed on whether precipitation will increase or decrease. The models project that the total annual precipitation varies from plus 9% to minus 9% or that the rainfall/ snowmelt that averaged 42.2 inches during the reference period (1988-1999) may stay within 4 inches of that average. Though, it is to be noted, that year to year weather variations in rainfall in the region are large, precipitation has varied from over 80 inches to below 20 inches in the past. Also, in the 18 climate scenarios, the increase in annual average temperature by 2040 increases for the area from 1.3 to 4.1 degrees Fahrenheit when compared with the reference period of 1988 to 1999. The average increase, over all scenarios is 2.7 degrees Fahrenheit. (These temperature predictions were the basis of the energy savings and water savings projects for my home that were geared for a slightly warmer, drier climate, though I am still hoping for wetter.)

Though annual rainfall increases in half of the climate change scenarios, flow in the Potomac River falls in most scenarios. Changes in both temperature and precipitation affect stream flows. Changes in rain or snow affect the amount of water that runs off the land surface and enters streams during rainfall. Precipitation also affects the amount of water recharging groundwater aquifers, which are the primary source of stream flow during dry weather periods. Increasing temperatures will cause more rain to be lost to evaporation from the soil, streams, and will increase transpiration, the water released to the atmosphere by plants. These increases in evaporation and transpiration will tend to reduce flow in streams which in turn reduces flow in the Potomac. With rising population, this could require changes in water use and supply for the area and reduce groundwater availability for private well owners like me.

Average annual basin-wide evaporation and transpiration is predicted to increase by 6-8%. Groundwater recharge decreases under all but three of the climate scenarios, and as I watch the statistically low water level in the monitoring well up the road, I worry about my well water supply. According to study results, the seasonal pattern of groundwater recharge does not change significantly under climate change, with January, February, and March remaining the months of greatest recharge. However, the average annual amount of groundwater that provides base flow to streams and the water in my well, is predicted to decrease in 16 out of the 18 scenarios by as much as 34% in one case.

Results for the 18 climate scenarios fell into three categories: minor impact, moderate impact, and major impact. The biggest impact is the ability of the regional water utilities to continue to supply water on demand during droughts as the climate changes. Six of the scenarios are predicted to have little impact on the system during a moderate drought and the projected population of the region can be supplied with drinking water from the Potomac River and current systems and operations. Six of the climate change scenarios fall into the “moderate impact” category. Under these scenarios the region is predicted to experience more frequent and stricter water use restrictions, but no water supply shortages during a moderate drought. Reservoir levels are predicted to fall to significantly lower levels during a drought than would occur in the absence of climate change with the projected and assumed increase in population.

However, the remaining six climate change scenarios are scary. Under these dreadful six scenarios, unless we make changes in the water supply systems we run out of water. These scenarios predict that both mandatory and emergency water use restrictions would be imposed and most system reservoirs would become empty or close to empty during a moderate drought. In addition, these six scenarios predict on some days of the drought the Potomac River would fail to provide sufficient water to meet demand and environmental needs. Our regional water utilities: The Washington Aqueduct, Washington Suburban Sanitary Commission (WSSC), and Fairfax Water working together with the ICPRB can make changes to the structure and operation of the water supply system to make it more robust. The Potomac River will continue to supply water to the region, we will have to use it more wisely to ensure adequate water supply in the future, but there will be water.  Clearly though, development in the groundwater recharge zones (mostly the Rural Crescent in Prince William County) and open areas needs to be limited to protect the groundwater and stream base flow that supplies our water.