Water In Eastern Prince William County

There was a Town Hall meeting held at Jenkins Elementary School on Thursday, June 2nd  2022 about the changes planned in land us in the Comprehensive Plan Update and Amendments and what the impact will be on Prince William County. Below is my talk:

If you live in the eastern portion of Prince William County you should care very much about the fate of the Rural Crescent because the Rural Crescent is about water, your water. The public water supply in eastern Prince William (blue) comes from the Occoquan Reservoir. PWSA purchases 15 million gallons of water a day from Fairfax Water for you- it is all drawn from the Occoquan Reservoir. 

The Rural Crescent allows rain water to flow gently over vegetation, feed the aquifers that provide water to the private wells and the Evergreen water system, but also feeds the tributaries to Bull Run and the Occoquan River assuring the base flow to the rivers and streams that feed the Reservoir.

Development will impair the recharge of the groundwater aquifer, but also increase sediment and salt flow into the Occoquan Reservoir, reduce stream flow and deteriorate water quality while increasing demand for water to feed more homes, businesses and data centers.

Development increases impervious cover from roads, pavement and buildings does two things. It reduces the open area for rain and snow to seep into the ground and percolate into the groundwater and the impervious surfaces cause stormwater velocity to increase preventing water from having enough time to percolate into the earth, increasing storm flooding and preventing recharge of groundwater from occurring. According to the EPA groundwater recharge is reduced from 50% to about 15% and runoff increases from around 10% to 55%.

When generally open rural area is developed stormwater runoff increases in quantity and velocity washing away stream banks, flooding roads and buildings, carrying fertilizers, oil, grease, and road salt to the Occoquan Reservoir. The salt level in the Occoquan Reservoir is rising almost to the critical point, Fairfax Water says it will cost $1-$2 billion to build desalination treatment their plants.

Our future and our children’s future is our water. We can’t allow it to be destroyed by paving roads and building data centers, warehouses and housing developments that will produce windfall profits for the landowners while leaving us with the bill of one to two  billion dollars to remove the increasing salt level from the Occoquan Waters.

Parts of California are Sinking a Foot a Year

Since the 1920s, excessive pumping of groundwater at thousands of wells in California’s San Joaquin Valley has caused land in sections of the valley to subside, or sink, by almost 30 feet. This subsidence is exacerbated during droughts, when farmers rely heavily on groundwater to sustain one of the most productive agricultural regions in the nation. Once the land subsides it's capacity to hold groundwater cannot be restored.

from Vasco et al

Subsidence induced by groundwater depletion is a grave problem in California’s Tulare Basin, and while certainly not surprise, scientists at NASA have been alarmed by how much faster the areas of the San Joaquin Valley are sinking during this extended drought period. NASA found that sections of the Tulare Basin are sinking at a rate of about a foot a year.

Subsidence can also cause structural damage to the infrastructure we build on top of the earth- like roads, bridges, and pipes.  Often, permanently losing storage space for water as the earth compacts. A group of scientists supported by their various organizations combined the data from two orbiting satellite-based systems to monitor the variations within the Tulare basin at various timescales.

Using the Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) observations, which provide estimates of the displacements of the Earth’s surface, and terrestrial water storage changes measured from NASA’s Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-on (FO) missions the scientists were able to model the groundwater changes.

 However,  changes in the gravity field sensed by GRACE and GRACE-FO can be traced to a variety of sources such as ground movement, soil moisture, water table variations, and snow cover. Thus, it was  diffcult, if not impossible, for the scientists to distinguish between water mass changes in the shallow unconfined aquifer and in the underlying confined aquifer using gravitational observations alone.

Corcoran clay separates the shallower unconfined aquifer from the confined aquifer below. Recharge occurs in the unconfined aquifer from snow, runoff, and precipitation. Groundwater storage in both the unconfined and confined aquifers is detected by the GRACE satellites. Compaction, believed to occur predominantly in the confined aquifer, causes the displacement of the Earth’s surface measured by Sentinel-1 Synthetic Aperture Radar (SAR) satellites.

Though much more work needs to be done, results suggest that available Sentinel and GRACE satellite data can indeed monitor hydrological variations over time. With future improvements in observations, and additional satellites planned for 2023, there should be even better monitoring of the changes in the Tulare basin in the future.

Read the article here if you are interested.

Vasco, Donald W., Kim, Kyra H., Farr, Tom G., Reager, J. T., Bekaert, David, Sangha, Simran S., Rutqvist, Jonny Beaudoing, Hiroko K., 2022/03/09: “Using Sentinel-1 and GRACE satellite data to monitor the hydrological variations within the Tulare Basin, California,” Scientific Reports, 3867 vol 12 issue 1.

Using Lidar to Measure Reservoir Storage

Elevation-Area-Capacity Relationships of LakePowell in 2018 and Estimated Loss of Storage Capacity Since 1963

Scientific Investigations Report 2022-5017
Water Resources Mission Area
Prepared in cooperation with the Bureau of Reclamation

For a while now, we’ve been waiting for LIDAR, light detection and ranging technology, to bring us the elusive self-driving car. Unfortunately, it always seem to be 5 years out. However, I read with amazement about a team of scientists from South America and the United Kingdom who used helicopter-mounted lidar to peer below the rainforest foliage and get a view of the remains of structures below the trees discovering villages that are hundreds of years old and had been swallowed by the jungle.

Now, scientists are finding many other uses for Lidar. The U.S. Geological Survey (USGS) , in cooperation with the Bureau of Reclamation (Reclamation), surveyed Lake Powell between fall 2017 and spring 2018 topographic light detection and ranging (lidar) data (land elevation) and multibeam bathymetry (bed elevation of a water body to calculate the capacity of Lake Powell, the second largest reservoir in the nation.

Lake Powell is located on the Colorado River across the Utah– Arizona border and was created in 1963 by the completion of the Glen Canyon Dam. Nearly 200 miles of the Colorado River was flooded upstream from the dam creating the reservoir/lake. In the United States only Lake Mead, which is approximately 300 miles downstream on the Colorado River is larger.

Though the instrumental record of the Upper Colorado River Basin is robust, with daily stream gage monitoring going back decades, only two studies have estimated the Lake Powell storage capacity. The original, pre-Glen Canyon Dam elevation-area-capacity tables (Bureau of Reclamation, 1963) that were calculated from contour maps and a reservoir-wide, range-line bathymetric survey that was completed 25 years post-impoundment in 1986 (Ferrari, 1988). Both studies utilized the best-available technology at the time but lacked the precision of current surveying methods.

Lake Powell has continuously trapped sediment from the sediment-laden Colorado and San Juan Rivers at the river deltas, diminishing the storage capacity at the highest elevations of the reservoir. During the most recent survey of Lake Powell, USGS scientists used high-resolution multibeam bathymetry and lidar to create the equivalent of an underwater topographic map of the reservoir. The data were then combined to create a topobathymetric digital elevation model (TBDEM), a continuous representation of submerged bathymetry and subaerial topography.

Just as the land above the water has its highs and lows, so too does the land beneath the water’s surface. Those features are known as bathymetry. In a reservoir the build-up of sediment slowly over time reduces the capacity of to the reservoir – how much water it can hold.

The lidar topographic data were acquired during a 2-day airborne survey on April 2 and April 3, 2018, and completed by The Atlantic Group, LLC they found that the total storage capacity of Lake Powell is now 25,160,000 acre-feet. This is a decrease of 1,833,000 acre-feet or 6.79% of storage capacity from 1963 to 2018. The average annual loss in storage capacity was approximately 33,270 acre-feet per year between 1963 and 2018.

Locally, the Occoquan Reservoir in an urbanized area has suffered a 15% loss of capacity associated with accelerated siltation over a shorter period of time.

Vanishing Groundwater

From  Famiglietti and Rodell 

In the August National Geographic is an article with great pictures about the Ogallala aquifer. The High Plains aquifer in the central United States running from South Dakota through Nebraska, Kansas, Colorado, New Mexico, Oklahoma to Texas is commonly known as the Ogallala aquifer (because the Ogallala formation makes up about three quarters of the aquifer) became news and burst into public awareness due to the protests associated with the Keystone XL Pipeline.

As highlighted by National Geographic there is a much bigger threat to the Ogallala; the aquifer is being depleted because the groundwater within much of it is predominately non-renewable. The groundwater aquifer that spans and estimated 174,000 square miles is the primary source of water for the High Plains. This was open range land until the groundwater from the aquifer was used to turn the range land into irrigated crops. However, according to John Opie in “Ogallala: Water for a Dry Land” this is essentially fossil water that was generated 10,000-25,000 years ago by the melting of the glaciers of the Rockies.

Groundwater laws and regulations vary by state. In Kansas and Nebraska the state owns the groundwater and rights to use the water were granted (in perpetuity) to property owners. Unfortunately, like water rights elsewhere rights granted for use often exceed water available. Where water is wealth, this happens over and over again. In Texas as in Virginia any groundwater you can pump from under your land is yours by right. Though the states are monitoring water usage, they do not have the political will to cut usage. While in Virginia we could limit use of groundwater to a level that would be sustainable, our aquifers are young and recharging; the High Plains aquifer could only manage the depletion of the aquifer. Farmers are selling their water in the form of cheap corn for ethanol, and their grandchildren or possibly even their children will have no water to farm. Everyone wants someone else to stop pumping groundwater. It does not seem possible to regulate and control private wells.

Science now can demonstrate the depletion. The Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) to quantify groundwater depletion are satellites that are used to measure changes in gravity caused by moisture. The satellites are used to measure monthly changes in total earth water storage by converting observed gravity anomalies they measure from space into changes of equivalent water content. This method of converting the gravity data to water data was developed by Matthew Rodell & James S. Famiglietti in 1999. Dr. Famiglietti and Dr. Rodell and a group of researchers at the University of California, Irvine, the University of Texas, and the Hydrological Sciences Branch at NASA GSFC have worked in partnership to apply GRACE and GLDAS to perform real world groundwater monitoring. NASA has been collecting data for more than 13 years. Last year they published two papers using the first 10 years of collected data to quantify groundwater use, resilience and stability. The news was not good.

Though, ten years of data may not be adequate to determine accurate changes in water availability and groundwater recharge. Using GRACE data, Drs. Famiglietti and Rodell identified what appear to be  areas of water depletion in the United States. These areas include the important food producing regions in California’s Central Valley, and the southern High Plains (the southern part of the Ogallala); large areas of the southeastern U. S. that has been plagued by persistent drought, including Alabama, and portions of the Mid-Atlantic region. Based on the data since 2003, the wetter, northern half of the U.S. has become wetter, while the drier, southern half has become generally drier. As seen in the diagram above, Virginia’s aquifers are under stress. It is difficult to undo water dependent development; however, it is essential that we prevent further development that would impact water sustainability.

On the most local level, Prince William county, we need to examine the sustainability of water resources as an essential part of the Comprehensive Plan. The current version of the comprehensive plan does not even consider water sustainability, and only mentions the Rural Crescent as requiring each single family home to have 10 acres. The basic zoning that exists now in the Rural Crescent is A1- agricultural, allowing one house per 10 acres. The real problem is that highest and best use of the land in the current environment is developing homes. Cutting up the rural crescent into 10 acre parcels or building large churches, schools or even random clustered developments reduces the groundwater recharge, increases the demand for water, increase the potential for contamination, erodes the land by increasing the stormwater velocity over pavement, roadways, buildings and increases sediment flow into our rivers and our Bay.

Whether or not continued residential growth will seriously deplete groundwater supplies is an open issue that has not been studied. But the failure of groundwater supplies or extensive contamination as has happened in areas of Fairfax and Loudoun Counties; however, could destroy property values (after all who buys a house without running water?) and lead to enormous additional costs to homeowners and taxpayers and a lower quality of life for all. Loudoun Water is spending tens of millions of dollars to solve the water problems in Raspberry Falls and Selma communities alone that they are charging to all water customers.

The Groundwater in the West is being Used Up

From Castle et.al.

A new study released last week by scientists at NASA Goddard Space Flight Center and University of California at Irvine has found that groundwater storage within the Colorado River Basin has been depleted by 41 million acre feet since late 2004. Most of the depletion has come since 2010 as the region endures an extended drought. This study is the first to quantify the amount groundwater used in the seven western states of the Colorado River Compact. According to the U.S. Bureau of Reclamation, the federal water management agency, the basin has been suffering from prolonged, severe drought since 2000 and has experienced the driest 14-year period in the last hundred years.

Observing the groundwater buried beneath layers of soil and rock was almost impossible until, the twin satellites known as the Gravity Recovery and Climate Experiment, or GRACE, were launched in March 2002. At the time few believed the satellites could measure changes in groundwater, but thanks to work of Dr. Jay (James S.) Famiglietti and his graduate student (at the time) Matt Rodell, who were then working at the University of Texas at Austin the techniques for measuring groundwater using the GRACE satellites were developed and proven. Expanding on that work is this new paper by Stephanie L. Castle, Brian F. Thomas, John T. Reager, Matthew Rodell, Sean C. Swenson, and James S. Famiglietti.

While the need to use groundwater resources to meet Basin water demands has long been recognized, the quantity of available groundwater and the sustainable rate of groundwater use are not known. As the drought in the western states has persisted for most of this century, water management under drought conditions has focused only on surface water resources- the flow of the Colorado, the levels in Lake Mead and Lake Powell. There is neither enough data nor a regulatory framework to fully manage groundwater. However, as this study shows us, by only managing the water withdrawals from the reservoirs (Lake Mead and Lake Powell) water use may not have been reduced at all, but instead groundwater may have made up more of the shortfall in water.

From Castle e.t al.

The study found that the Colorado River Basin lost almost 53 million acre feet of water over the study period with 12 million acre feet coming from the falling level in the two reservoirs and the remaining 41 million acre feet being pumped out from groundwater. The scientists estimated changes in groundwater storage during the 9-year drought period, when reservoir volumes were intensively managed to maintain hydropower production, maintain water levels above the public supply water intake pumps, and to meet surface water allocations to the Basin states using the methods developed by Drs. Jay Famiglietti and Matt Rodell.

The total water storage in a region as seen by the satellites is comprised of soil moisture, snow water equivalent, surface water (including river flow and reservoirs), and groundwater. Accessible water is assumed to be surface water reservoir storage and groundwater storage. They assumed Lakes Mead and Powell accounted for the majority of the observed surface water change as they comprise approximately four times the annual flow of the river and make up 85% of surface water in the Basin at any time. So the flow of the river was ignored introducing an error of 5%-15%. USGS and ADWR monitoring wells in the Colorado Basin showed good agreement with the GRACE-based estimates further confirming the methodology.

A brief recovery in groundwater storage was observed in the data from June 2009-March 2010, when moderately wetter conditions provided a combination of potential groundwater recharge and temporarily alleviated the need to augment surface water supplies, but the overall observed trend is not good. As the Bureau of Reclamation more tightly controlled and limited surface withdrawals, groundwater reserves were tapped to make up the loss, demonstrating the close connection between surface water availability and groundwater use. As available water in the west has been diminished by an extended drought and demand for water has actually increased over these years, solely managing surface water in the Colorado Basin, without regard to groundwater loss, has resulted in the 41 million acre foot reduction in ground water reserves which predominately occurred from April 2010 to November 2013.

Groundwater is typically used to augment the limited surface water supplies in the arid, Lower Colorado Basin and across the entire Basin during drought. Groundwater represents the largest supply of water for irrigation within the Basin and against all reason irrigated acreage in the Colorado Basin increased during the study period. Furthermore, according to Drs. Famiglietti and Rodell, the prolonged drought across the southwestern region of the United States has resulted in overreliance on groundwater by public water to minimize impacts of the drought on public water supply. The decrease of an average of 4.5 million acre feet of groundwater each year may merely reflect the problems with the Colorado River Compact, the regulatory framework already in place to manage surface waters. The Compact which allocates the flow of the Colorado River to Colorado, Utah, Wyoming, New Mexico, Arizona, Nevada and California and through a 1944 treaty to Mexico promised what turned out to be more than 100% of the water available at the time and the current researchers believe that the over allocation of the Colorado River’s water was 30% during the study period based on the groundwater loss of 4.5 million acre feet a year from the groundwater reserves.

Specifically, the amount of water allocated under the Colorado Compact was based on an expectation that the river's average flow was 16.5 million acre feet per year. 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 and climate forecasts for the future are dire. The political hurdles the Colorado River Compact may need to be renegotiated and include groundwater resources. 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 current drought in California has only emphasized the need for more active and enforceable groundwater management throughout the Basin, in particular, during drought. During the study period the scientists observed that groundwater is already being used to fill the gap between Basin demands and the annual, renewable surface water supply.

Managing groundwater is a daunting task. Even today groundwater sustainability is still not fully understood. In addition, there are droughts, climate changes; water draws from surface water changes the recharge rate of the groundwater. The U.S. Geological Survey did not begin quantitative analysis of the major groundwater systems of the United States until 1978 and since that time there has been tremendous evolution in the understanding of and ability to model groundwater systems. Before the groundwater basin is irreparably overdrawn, we need to understand what sustainable water use in the region is and embrace it. Otherwise the groundwater will be pumped until it is gone.

See the excellent blog post by Jay Famiglietti

What’s EPA Doing about Fracking?

EPA will be holding a webinar on their fracking studies that includes research approach, status, and next steps if you are interested. The webinar will be presented on two different days, Thursday, January 3rd and Friday, January 4th 2013. Jeanne Briskin, Hydraulic Fracturing Research Coordinator, Office of Science Policy, Office of Research and Development will be the instructor and the webinars are: on January 3, 2013, 2:00 PM - 3:00 PM, EST and January 4, 2013, 12:00 PM - 1:00 PM, EST. Just click through on the links and sign up.

The United States has vast reserves of natural gas within shale and rock formations. During the past decade, extracting that gas has become commercially viable as a result of the advances made in horizontal drilling and hydraulic fracturing (fracking) techniques. With the rapid increase in fracking has come the increase in concerns about its potential impacts on drinking water. In response to public concern ignited by the film Gasland and protests by anti-fracking groups, the US House of Representatives requested that the US Environmental Protection Agency (EPA) examine the relationship between fracking and drinking water resources in 2009. In 2011, the EPA began a series of research projects into the impacts and potential impacts of fracking on water. Also, in April 2012 EPA released the first federal air rules for natural gas wells that are hydraulically fractured, specificallyvrequiring operators of new fractured natural gas wells to use “green completion,” which is a series of technologies and practices to capture natural gas and other volatile substance that might otherwise escape the well during the completion period when most volatile release takes place.

Hydraulic fracturing has its own water cycle and involves the pressurized injection of fluids commonly made up of mostly water and chemical additives into a geologic formation. The pressure used exceeds the rock strength and the fluid opens or enlarges fractures in the rock. As the formation is fractured, a “propping agent,” such as sand or ceramic beads, is pumped into the fractures to keep them from closing as the pumping pressure is released. The fracturing fluids (water and chemical additives) are partially recovered and returned to the surface. Natural gas will flow from pores and fractures in the rock into the wells allowing for enhanced access to the methane reserve. Two to five million gallons of water are typically necessary to frack one horizontal well in a shale formation. Water used for fracturing fluids is acquired from surface water or groundwater in the local area. Wastewaters from the hydraulic fracturing process (flowback or water produced in the well) may be disposed in several ways. The water that flows back after fracturing may be returned underground using injection well, discharged to surface waters after treatment to remove contaminants, or applied to land surfaces. Not all fracturing fluids injected into the geologic formation during hydraulic fracturing are recovered. The EPA estimates that the fluids recovered range from 15-80% of the volume injected depending on the site. The long term fate of any residual fluid has not been studied.  

Each stage of the fracking water cycle is a potential area for impact to drinking water supplies especially from human error and irresponsibly and improperly handling chemicals and contaminated water and poorly managing and protecting our water resources.  The steps in the fracking water cycle are:

Water acquisition. Chemical mixing. Pressurized Well injection. Flowback and produced water (collectively referred to as “hydraulic fracturing wastewater”) recovery. Wastewater treatment and disposal. Geology, hydrology and human behavior will produce vastly different outcomes for different regions of the county and different gas companies.

from US EPA

EPA is engaged in a number of research projects that will be the basis of their actions and future regulations for oil and gas operations. Whether the EPA will regulate oil and gas exploration nationally or leave the oversight in the hands of the states is an open question. There is an argument that water resources and geology are very local phenomena and cannot be generalized over the nation and that hydraulic fracturing should remain under local oversight. The 2005 energy law exempts fracking from the Safe Drinking Water Act based on the 2004 EPA study “Evaluation of Impacts to Underground Sources of Drinking Water by Hydraulic Fracturing of Coalbed Methane Reservoirs.” In that report EPA reviewed 11 major coal basins mined for coalbed methane and saw no conclusive evidence that water quality degradation on underground drinking water supplies had occurred as a direct result of the injection of hydraulic fracturing fluids, but fracking of coalbeds generally involves a fraction of the water used in hydraulic fracking of shale gas.

The current fracking projects are a series of studies. Existing Data from multiple sources have been obtained for review and analysis. Well construction and hydraulic fracturing records provided by well drillers are being reviewed for 333 oil and gas wells across the United States; data within these records are being examined to assess the effectiveness of current well construction practices at containing gases and liquids before, during, and after hydraulic fracturing. In addition information on the chemicals and practices used in hydraulic fracturing has been collected from nine companies that hydraulically fractured a total of 24,925 wells between September 2009 and October 2010. Data on causes and volumes of spills of hydraulic fracturing fluids and wastewater are being collected and reviewed from state spill databases.

Computer models are being developed to identify conditions that may lead to impacts on drinking water resources from hydraulic fracturing. The EPA has created hypothetical scenarios for  water acquisition, well injection, and wastewater treatment and waste disposal stages of the water cycle that they hope to have the models evaluate. Computer models are also being used to explore the possibility of subsurface gas and fluid migration from deep shale formations to overlying aquifers in six different scenarios. The effectiveness of the models would be dependent on how closely the model predicts transport behavior in rock and shale and the similarity in behavior of different formations.

Laboratory studies are being performed to identifying potential impacts of inadequately treating hydraulic fracturing wastewater and discharging it to rivers. Experiments are being designed to test how well common wastewater treatment processes remove selected contaminants from hydraulic fracturing wastewater, including radium and other metals. Since wastewater treatment plants are not designed to remove more than biological waste and bacteria, any removal of fracking chemicals and contaminants would be incidental. I do not expect that wastewater treatment plants would be able to treat flowback water for the contaminants associated with geological formations and fracking chemicals.

The EPA has identified chemicals used in hydraulic fracturing fluids from 2005 to 2011 and chemicals found in flowback and produced water. The EPA is performing toxicity assessments based on chemical, physical, and toxicological properties for chemicals with known chemical structures. Existing toxicology models are being used to estimate properties in cases where information is not available. The important thing that EPA is doing is bringing together all the data and previous work to get as complete picture of what we know about how hydraulic fracturing may be impacting our water resources.