The Formation of Streams

 The Birth and Growth of Streams

Streams and rivers are an essential part of our water supply, but where do they come from? Streams form through the combined effects of gravity and the accumulation of water from various sources, including rain, melting snow, and underground springs. These initial flows are typically small, but as they travel across the landscape, they eventually merge to form larger river systems.

Headwaters and Surface Runoff

Streams begin at a high point known as the headwaters or source. When precipitation exceeds the soil’s capacity to absorb water, the excess flows downhill as surface runoff, collecting in lower areas. This runoff carves out small, temporary trenches called rills, which widen and deepen into larger channels known as gullies over time. Some streams are also sustained by springs or the water table. The water table, marking the upper boundary of groundwater, must maintain contact with a stream to continue feeding it. When a riverbank intersects a saturated layer of earth, groundwater seeps out, supporting the stream’s flow even during dry periods.

How Streams Become Rivers

As water continues its downhill journey toward its base level—such as the Bay or Occoquan Reservoir—small streams join together to form larger bodies of water. Examples of these smaller streams or rivers include Broad Run, Cedar Run, Slate Run, Bull Run, and Catharpin Creek, which all contribute to a larger “parent” river like the Occoquan River. The specific location where two streams or a tributary and a river meet is known as a confluence. This branching network of tributaries, which gathers water from a defined land area, is referred to as a watershed or drainage basin.

The Importance of Groundwater

Groundwater is a crucial source of water for streams and rivers, often providing 30% to over 50% of their total annual flow. This steady, slow-moving contribution is called baseflow, acting as a “savings account” that sustains streams over time.

Gaining Streams and the Water Table

In many areas, streams are classified as “gaining” streams because they receive a direct supply of water from the ground. For groundwater to enter a stream, the water table—the top of the underground saturated zone—must be higher than the stream’s water level. Water naturally moves from regions of high pressure (saturated ground) to lower pressure (the open stream channel), seeping through the streambed and banks. However, if groundwater is excessively withdrawn or if groundwater recharge is reduced—such as by increasing impervious surfaces through land use change—the connection between groundwater and the stream can be severed.

Groundwater’s Role in Sustaining Flow

Groundwater is the main reason why many rivers continue to flow even during extended periods without rain. While rainwater, or runoff, reaches a river quickly, groundwater may take days, months, or even years to move through soil and rock before eventually seeping into a stream. This process provides a steady flow between rainstorms, ensuring a reliable minimum water supply that supports aquatic life and meets human needs during dry spells. This process is also why land use changes may take decades to impair stream flow.

Ecological Impacts of Groundwater and Streams

The interaction between groundwater and streams does more than maintain water levels; it also supports ecological health. Because groundwater remains at a fairly constant temperature throughout the year, it keeps streams cooler in summer and warmer in winter, creating vital “thermal refuges” for fish and other aquatic life. As water circulates between the ground and the stream, it transports carbon, oxygen, and nutrients that nourish complex ecosystems within he hyporheic zone—the saturated sediment layer just beneath the streambed. Without the groundwater flow streams loose this ability to support the living ecology.

Human Impacts on Groundwater and Streams

Human activities, changes in land use, and climate change can disrupt the natural connection between groundwater and streams. Excessive pumping from wells can lower the water table below the level of a stream, causing the stream to lose water to the ground or even run dry. Another significant impact comes from impervious surfaces, such as pavement and buildings, which prevent rainwater from soaking into the ground and recharging groundwater. This eventually leads to a lower water table and reduced baseflow in local streams.

Drought Expands

All of the Potomac watershed is currently in drought. The U.S. Drought Monitor Map released last Thursday shows shows 88.8% of the Potomac Basin in Severe Drought and  11.2% in Moderate Drought. The current conditions have triggered the Virginia Department of Environmental Quality (DEQ) to issue a drought warning advisory for 22 counties and 13 cities, and expanded the drought watch advisory to now include 61 counties and 18 cities in Virginia.  For now, the Potomac River’s flows are adequate to meet the water demands of the Washington metropolitan area, but are well below normal for this time of year.

A drought warning advisory is intended to increase awareness that the onset of a significant drought event is imminent and includes the following areas:

• Northern Virginia: Arlington, Fairfax, Fauquier, Loudoun, and Prince William counties and the cities of Alexandria, Fairfax, Falls Church, Manassas, and Manassas Park. 
• Roanoke River: Bedford, Campbell, Charlotte, Franklin, Halifax, Henry, Mecklenburg, Patrick, Pittsylvania, and Roanoke counties and the cities of Danville, Martinsville, Roanoke, and Salem. 
• Shenandoah: Augusta, Clarke, Frederick, Page, Rockingham, Shenandoah, and Warren counties and the cities of Harrisonburg, Staunton, Waynesboro, and Winchester.  

 Here in Prince William County Virginia rainfall averages approximately 44 inches per year, but varies from year to year. Last year we were about 9 inches short of average and in the first 4 months of this water year we have had about half the usual amount of rainfall.  Climate forecasts are for our region to get wetter with more intense rainstorms and droughts to get more severe. (ICPRB).

This precipitation deficit continues and has resulted in further declines and sustained much-below normal streamflow, groundwater, and soil moisture levels throughout most of the Commonwealth, especially in the Piedmont and Blue Ridge regions. Reservoir levels remain largely normal, except for Smith Mountain Lake, which is 0.26 feet below Warning level (791.5 ft) and Lake Moomaw, which is currently 1.48 feet below the watch threshold.

from DEQ

DEQ is working with local governments, public water works, and water users in the affected areas to ensure that conservation and drought response plans and ordinances are followed. Be alert for drought response notifications. Though, at least we do not have to worry about people water their lawns and plants and using more water when they should be conserving (which happened two summers ago).

The Magnificent Woodland

We are now entering the seventh year of my woodland restoration project. My property is just over ten acres, with about three acres dedicated to lawn and ornamental gardens. The remaining seven acres consist of woodland, much of which falls within the Chesapeake Bay's "resource protected area" (RPA).

When we first arrived, I didn’t worry about dead trees—they’re an important part of nature’s renewal process. A thriving forest features living trees that are part of a complex ecosystem along with understory shrubs and groundcover. Natural succession means saplings will eventually replace aging trees. For years, my approach to the RPA was one of benign neglect, letting nature protect the stream.

However, around ten years ago, I saw signs that something was going wrong. Invasive insects, rampant vines, and a dramatic increase in deer and other wildlife started to damage the woodland. Deer favor native plants, eating young tree saplings while leaving invasive species like autumn olive untouched. As gaps appeared in the canopy, invasive vines and shrubs moved in instead of young native trees.

The woodland before Wetland Studies and Solutions began work in this section

Woodlands play a crucial role in ecological balance. The tree canopy—made up of leaves, branches, and bark—acts as a shield during storms, intercepting and slowing rainfall. A mature tree can hold over 100 gallons of water during a single rain event, and this slows water flow. By catching raindrops before they hit the ground, vegetation reduces erosion and keeps soil from clogging up with particles. Water intercepted by trees either drips down or runs along trunks, reaching the ground slowly and helping prevent rapid surges that can overload storm drains.

Trees and natural plants transform soil, making it more absorbent. Their deep root systems create channels for water to soak in rather than collecting on the surface. As roots grow and decay, they contribute organic material, binding soil into stable aggregates and enhancing its ability to store water—even where soils are compacted by urban activity. Fallen leaves and decaying plant matter form a spongy layer that further traps water, allowing it to filter gently into the earth.

Plants and trees also act as pumps, returning water to the atmosphere through evapotranspiration. Roots draw moisture from the earth, which is then released as vapor through leaf pores, while water caught on surfaces evaporates directly back into the air. This ongoing cycle clears space in the soil, so it’s ready to absorb rain again.

Finally, stems, stalks, and leaves slow water movement over the land. Dense growth like tall grass and shrubs creates friction, lowering water speed. Riparian buffers—like my woodland along Chestnut Lick—help slow floodwaters and reduce erosion, preventing bank collapse and minimizing downstream flooding.

credit Steve Ward

Last summer we came to the conclusion that the money and time that has been poured into the woodland was worth it. However, we also realized that this project will never end. 

Impacts of Land Use Change on a Watershed

A watershed is an area of land that collects precipitation, such as rainfall and snow, and directs it into a common water body—whether a stream, river, or, in the case of Prince William County, the Occoquan Reservoir. Land use changes can dramatically alter the natural functioning of watersheds, with impacts beginning almost immediately after land is cleared, leveled, or developed with roads and impervious surfaces. These changes result in increased volume and speed of stormwater runoff. Over the course of 20 to 50 years, initial disturbances lead to lasting ecological and physical transformations. When 35–50% of a forested watershed is replaced by impervious surfaces—well above the 10% threshold where significant degradation typically starts—the movement and fate of water within the landscape are permanently altered.

When Impacts Happen

Watersheds respond quickly to shifts in land use. The removal of vegetation and the installation of pavement cause stormwater runoff to become nearly instantaneous during rainfall events, with surface runoff reaching up to 16 times that of undisturbed areas. This dramatic increase highlights the immediate impact of development. To address these concerns, stormwater management measures are often integrated into development plans, aiming to slow, capture, and treat runoff before it enters local water bodies.

• Short-Term (1–10 Years): Substantial increases in streamflow and sediment loads occur soon after clear-cutting and construction activities.
• Long-Term (20–50 Years): Over decades, cumulative effects emerge, such as persistent deficits in soil moisture and changes in water flow pathways due to road networks and infrastructure.

What are the Impacts to the Watershed

When impervious surfaces account for 35–50% of a watershed, notable hydrological and ecological changes take place. Pavement and buildings prevent precipitation from soaking into the soil. Under natural conditions, much of the rainfall infiltrates the ground, helping to replenish aquifers. However, when surfaces are sealed, infiltration declines sharply, which in turn reduces groundwater recharge.

During dry periods, streams depend on groundwater—known as baseflow—to maintain their flow. A high percentage of impervious cover reduces this recharge, lowering groundwater levels and separating streams from their underlying water sources. This results in reduced streamflow during dry spells and can transform perennial streams into intermittent ones.

Hydrological Changes

Flashier Streams: Stormwater runoff reaches streams more rapidly and in larger volumes, causing higher peak flows and more frequent flooding.

Reduced Groundwater Recharge: Impervious surfaces prevent water from infiltrating the soil, leading to lower water tables and streams that may dry up during summer months, ultimately causing streams to become intermittent.

Physical and Water Quality Changes

Increased speed and volume of stormwater runoff erode stream banks, cause incision (downcutting), and result in "blowouts" that destroy aquatic habitats. Stormwater runoff collects contaminants such as oils, heavy metals, road salts, and nutrients (nitrates and phosphates) from paved surfaces, and carries them directly into waterways without the natural filtering effects of forests. Rainwater heats up as it travels over sun-exposed pavement, raising stream temperatures and stressing or killing sensitive aquatic organisms. The reduced groundwater availability limits natural cooling, resulting in higher temperatures in urban and suburban areas.

Ecological Decline

At high levels of development, sensitive species such as trout and salamanders disappear, leaving only more pollution-tolerant organisms. The removal of old-growth trees eliminates deep roots and canopies that previously provided carbon storage, pollutant trapping, and soil stabilization, leading to further ecological imbalance.

Role and Limitations of Green Infrastructure & LID Features

Green Infrastructure (GI) and Low Impact Development (LID) are increasingly promoted as solutions to watershed challenges. These approaches focus on natural processes—such as infiltration, evaporation, and transpiration—to manage water where it falls. However, their effectiveness is generally limited to handling the first inch of rainfall, making them an incomplete solution for all impacts of land use change.

Unlike forests, which are self-sustaining, GI requires ongoing maintenance. For example, permeable pavements must be vacuumed to prevent clogging, and bioswales need sediment removal to maintain infiltration rates. Research suggests that Green Infrastructure should be designed for future climate scenarios, including increased storm intensity, to ensure sustainability over a 20-year lifecycle.

While GI and LID strategies can reduce the impacts of 35–50% development, they typically result in a "managed" watershed that is more costly to operate and more vulnerable to extreme weather events than a natural system. In watersheds with 35–50% impervious cover, Green Infrastructure is moderately effective at improving groundwater recharge, but its success depends on implementation density, storm event scale, and system maintenance. Unlike forests, GI systems require routine human intervention, such as vacuuming permeable pavements and maintaining bioswales, which are ineffective as roadways and in regions with frequent freeze-thaw cycles.

Green Infrastructure aims to slow down water movement and promote infiltration. It is most effective for frequent, low-intensity rainfall events (typically less than 0.8 to 1.0 inch). In these cases, dense GI installations can capture and infiltrate enough water to closely mimic natural forested conditions. Studies of urban catchments with approximately 35% impervious cover have shown that retrofitting with GI elements like rain gardens and porous pavements can increase infiltration and reduce total surface runoff.

In highly urbanized areas with 64% impervious cover, only about 2.4% of rainfall naturally infiltrates the ground. Implementing infiltration practices in zones with high impervious surfaces can raise this rate to roughly 5.2%, doubling recharge. This is still far below the recharge in a natural environment which is about 50%.

 

from U.S. EPA

 References:

Pegah Jalali, Sergey Rabotyagov, Quantifying cumulative effectiveness of green stormwater infrastructure in improving water quality, Science of The Total Environment, Volume 731, 2020, 138953, ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv.2020.138953.

 https://www.mdpi.com/2073-4441/11/10/1992

Alam, T.; Mahmoud, A.; Jones, K.D.; Bezares-Cruz, J.C.; Guerrero, J. A Comparison of Three Types of Permeable Pavements for Urban Runoff Mitigation in the Semi-Arid South Texas, U.S.A. Water 2019, 11, 1992. https://doi.org/10.3390/w11101992

 Zuo, Shangjun. (2025). Green Infrastructure / LID for Urban Stormwater Management. Science and Technology of Engineering, Chemistry and Environmental Protection. 1. 10.61173/pz840329.

The Occoquan Reservoir and Overlay Protection Area (ORPA)

ORPA from PWC

To ensure the protection of the Occoquan Reservoir—a primary drinking water source for eastern Prince William County and eastern Fairfax County—Prince William County established an overlay district in the lower Occoquan Watershed, known as the ORPA. Despite the intent of this protective measure, subsequent rezoning requests from developers has led to exemptions for some of the largest undeveloped parcels, which were recently approved by the Prince William Board of County Supervisors. The fundamental objective of the ORPA is to maintain natural landscapes, limit higher-density development and safeguard the region’s drinking water supply for both well owners and municipal customers; however, recent board actions have not aligned with these priorities.

Urbanization and Watershed Health

Although other parts of the United States may feature higher urban densities, the Occoquan watershed is regarded as the most urbanized while still retaining a functional watershed system. Preserving the watershed and its drinking water resources is essential, but the impact of land use decisions may only become evident over decades due to the slow pace of ecological change.

Groundwater functions as a reserve for rivers and streams, replenished through precipitation and subject to fluctuations stemming from rainfall patterns and land use alterations. Maintaining groundwater recharge within the Occoquan watershed is crucial for sustaining local water supplies and supporting river and stream ecosystems.

Impact of Land Use on Water Resources

Increases in impervious surfaces, such as roads, pavement, and buildings, exceeding 5–10% of an area can have two critical consequences: reduced infiltration of precipitation and accelerated stormwater runoff, both of which hinder groundwater recharge. These effects contribute to increased flooding and diminished water reserves over time. As groundwater levels decline, perennial streams supplying rivers transform into ephemeral flows, disconnected from surface water systems. Research indicates that watersheds experience degradation once 5–10% of their area is developed, although limited restoration potential remains initially. When urbanization surpasses the tipping point, water quality ceases to respond to remediation efforts, and complete restoration of the watershed becomes unattainable. Data from the Northern Virginia Regional Commission (NVRC) shows that by 2015, impervious surfaces in the lower Occoquan area had already reached 11%.

Interconnectedness of Water Resources

The preservation of the Occoquan Reservoir, serving over 800,000 residents, is intrinsically linked with the protection of all water sources in the region. Hydrologic connectivity ensures that precipitation enters the water table, contributes to groundwater, and feeds directly into streams and rivers. Disrupting this hydrological balance has broad consequences. The water supply for the Occoquan Reservoir comes from multiple sources: Bull Run Watershed (25%), Occoquan River Watershed (48%), groundwater and other watershed (21%), and reclaimed water from UOSA (6%). Should the watershed be compromised, only stormwater runoff and UOSA-reclaimed water would remain viable.

The Hydrologic Cycle and Growing Demand

A functioning watershed continually renews freshwater supplies via the hydrologic cycle, supplemented in the case of the Occoquan Reservoir by returning reclaimed wastewater to the Occoquan River. However, population growth, increased affluence, and expanded commercial activity increase water demand. Since the inception of the Occoquan Reservoir management plan nearly five decades ago, the regional population has grown six-fold. The original objectives included implementing advanced water treatment technologies, ensuring all reclaimed water met stringent standards prior to discharge, and capping the basin population at 100,000.

Groundwater Characteristics in Prince William County

Groundwater quantity and quality in Prince William County vary according to the underlying geology and hydrogeology. Generally, recharge occurs at higher elevations, with flow toward streams and estuaries, though these dynamics differ between consolidated rock formations and unconsolidated sediments. The proposed ORPA area, located outside the Culpeper Basin but within the Piedmont geologic province, primarily features hydrogeologic group D (igneous rocks), with transitions toward group E and the Coastal Plain in certain sectors.

Wells located here are highly vulnerable to drought conditions and often yield slightly acidic water. The igneous substrate exhibits subhorizontal sheeting and vertical joints beneath substantial overburden, producing well yields ranging from 1.2 to 100 gallons per minute. These characteristics support the prevalence of private household wells within the area. The only proxy well for Hydrogeologic group D, situated in Prince William Forest Park—the county’s least disturbed area—shows declining groundwater trends, but data remain insufficient to assess long-term sustainability.

Threats to the Region’s Water Supply

Significant threats to the region’s water resources stem from the conversion of woodland and open space to impervious surfaces, which eliminate groundwater recharge and reduce streamflow. The rapid loss of forest cover lowers water tables, degrades habitats, intensifies drought conditions, and raises salinity levels. In just seven years, Prince William County lost nearly 2,000 acres of tree canopy to development.

As highlighted by Dr. Stanley Grant, director of the Occoquan Watershed Monitoring Laboratory, emerging water quality challenges originate from ongoing urban expansion. The sustainability of the water supply for the 800,000 residents dependent on the Occoquan Watershed is jeopardized by increasing population densities and impervious surfaces. Once the density exceeds 100 people per square mile, the rate of impervious cover increases rapidly, threatening the continued existence of the nation’s most urbanized functional watershed and driving up water supply costs.

Rising Salinity and the Cost of Water

Salinity in the reservoir continues to rise, potentially approaching critical thresholds. Increased salt concentrations result primarily from winter road treatments during wet periods and reclaimed UOSA water during dry spells. Projected trends indicate further sodium increases due to cooling discharges from data centers and continued population growth. Expanded impervious coverage exacerbates salt runoff into the watershed.

Currently, removing salt from drinking water requires investing billions in desalination infrastructure, as regional plants lack this capability. Continued suburban sprawl into previously undeveloped areas will first elevate both water infrastructure costs and the cost of water for the residents. Then, diminished water availability will become the growing problem.

The Report Card for America 2025

 Every four years, the American Society of Civil Engineers’ (ASCE) Report Card for America’s Infrastructure evaluates the condition and performance of American infrastructure. The ASCE assigns letter grades based on the physical condition and needed investments for improvement. The 2025 ASCE Report Card for America's Infrastructure gave the United States an overall grade of C, the highest cumulative grade since ASCE began issuing assessments in 1998. This is an improvement from the C- awarded in the 2021 report and D+ awarded in 2017 and 2013 and the D in 2009. We are moving in the right direction mostly attributed to recent significant investment in infrastructure.

Infrastructure is the backbone of the U.S. economy. It is critical to our nation’s prosperity and the public’s health and welfare. For the U.S. economy to be the most competitive in the world, we need a first class infrastructure system – transport systems that move people and goods efficiently and at reasonable cost by land, water, and air; transmission systems that deliver reliable, low-cost power from a wide range of energy sources to balance intermittent and dispatchable; and water systems that drive industrial processes as well as the daily functions in our homes. Yet our investment in infrastructure had been faltering for decades. We have failed to maintain and expand the infrastructure built by our parents and grandparents.

Only recently, have we as a nation begun to address this. The grade improvement in 2025 is largely attributed to the Infrastructure Investment and Jobs Act (IIJA), which has funded over 60,000 projects since 2021. However, while economists generally agree that the U.S. can run budget deficits for extended periods, doing so perpetually at current levels is considered unsustainable and carries significant long-term risks. There are signs that other nations are turning to alternatives rather than the us dollar as the reserve currency.

Despite the new-high grade of C, aging systems are in need of more investment. The aging infrastructure is  increasingly vulnerable to extreme weather. The ASCE reports that 27 weather related events in 2024 alone caused over $182 billion in damages. The ASCE estimates investment needs total $9.1 trillion for all 18 current Report Card categories to reach a state of good repair over the next 10 years. Public data and ASCE’s 2024 Bridging the Gap study forecast $5.4 trillion in public and private investments in the 10-year period, 2024 through 2033, if Congress continues recent funding levels. This leaves a gap of $3.7 trillion in investments for America’s infrastructure if we keep investing at current funding levels. However, if Congress were to snap back to investment levels in place prior to recent increases in federal spending, that gap would increase significantly.

Poor infrastructure currently costs the average American household approximately $2,000 to $2,700 annually due to delays and inefficiencies. The costs of doing business and, therefore, prices will increase if surface transportation systems worsen, ports, airports and inland waterways become further outdated or congested, and if water, wastewater and electricity infrastructure systems continue to deteriorate or fail to keep up with changing demand. Increased reliance on electricity to support AI and data-driven systems and industries is particularly important when the cost of service outages and interruptions is business failure. Irregular delivery of water and wastewater services and electricity will make production processes more expensive and divert household disposable income to these basic necessities

However, the United States is no longer as rich a nation as we once were. We are spending more than the nation is taking in. Economists generally agree that while the U.S. can run budget deficits for extended periods, doing so perpetually at current levels is considered unsustainable and carries significant long-term risks. To address the national budget deficit while ensuring necessary infrastructure investments, experts and policymakers have proposed a range of significant spending cuts, increased taxes and alternative financing mechanisms. Balancing these competing priorities should involves a combination of reducing non-infrastructure spending and leveraging private capital, but often involves reducing the investment in maintaining infrastructure. 

The Congressional Budget Office (CBO) expects federal debt to reach 118% of GDP by 2035 and potentially exceed 200% by 2049. Net interest outlays are becoming the primary driver of the deficit. In 2026, interest payments are the second-largest federal expense, costing nearly $1 trillion annually. The annual budget deficit is around $2 trillion. This cannot be allowed to continue. Persistently high deficits are projected to cause several "drag" effects on the nation's future. Heavy government borrowing reduces available capital for private investment, which slows productivity and wage growth.

As the national debt grows the nation must pay higher interest rates to induce other nations to buy the debt. We, as a nation, have less ability to respond to crises (recessions, wars, national disasters or pandemics) because a higher portion of the budget is locked into interest payments. Excessive borrowing is already eroding the U.S. dollar's status as the global reserve currency, making it harder and more expensive to finance future debt. Economists also broadly agree that the growing national debt—which surpassed $38 trillion by late 2025 is considered a major risk to long-term price stability

The Rural Crescent Was about Water

The update to the Comprehensive Plan, Pathway to 2040 does us no favors. It sacrificed the sustainability and quality of our water resources for greenfield development and growth through sprawl. Removing the protected Rural Crescent from the Prince William County comprehensive plan and allowing for higher density sprawling suburban development, even with green infrastructure (GI), will over time likely result in impairment to our water resources that provide the fresh source water for the Occoquan Reservoir. 

The Rural Crescent, established in 1998, acted as a crucial urban growth boundary, protecting an extensive area of undeveloped farmland and forests. Its primary functions, which are vital for the county's water supply, include: 

• Watershed protection: It covered most of the Prince William County’s 40% of the Occoquan Watershed, a key source of public drinking water for a large portion of Northern Virginia.
• Groundwater recharge: The large amount of open, pervious land allowed rainwater to slowly infiltrate the ground, replenishing the aquifers that supply wells for the western part of the county and providing base flow to the streams and creeks that come together to form Bull Run and the Occoquan River.
• Pollutant filtration: The natural landscape's vegetation and soil effectively filtered pollutants before they enter local streams and the Occoquan Reservoir. 

Higher density sprawling suburban development fundamentally alters these natural processes by introducing vast areas of impervious surfaces (roofs, roads, parking lots). This leads to: 

• Increased and rapid stormwater runoff: This causes erosion, flooding, and carries pollutants directly into waterways.
• Inland salinization: More roads and neighborhoods increase the amount of seasonal salting and increases the salinity of our streams, creeks, and rivers -all our water resources.
• Reduced groundwater recharge: Water cannot penetrate impervious surfaces, putting groundwater supplies at risk as well as impairing our perennial streams which depend on the surface /groundwater interface to survive.
• Infrastructure strain: High-density development requires the extension of public water and sewer lines, which has historically been restricted in the Rural Crescent to prevent this very sprawl and its associated costs and environmental impacts. 

While green infrastructure practices (like rain gardens and permeable pavements) are effective at managing stormwater within developed areas, they cannot fully replicate the scale and efficiency of a vast, naturally functioning forest and open space ecosystem. Preserving large natural landscapes is widely considered the most effective method for protecting regional water resources. Green Infrastructure is a necessary mitigation tool within existing or designated development areas, not a substitute for the preservation of critical environmental lands.