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Groundwater
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class="breadcrumbs__item"><a href="https://www.chesapeakebay.net/issues" class="breadcrumbs__link">Learn the Issues</a></li> </ol> </nav> <h1 class="pageHeader__title">Groundwater</h1> <div class="blurb pageHeader__blurb"><p>Drops of rain or snow that fall onto the land can seep through the soil and into groundwater, which can become contaminated when pollutants on land seep underground.</p></div> </div> </header> <section class="l-master__main l-twoColumn" id="" > <div class="l-twoColumn__main" id="two-column-main"> <figure id="8bed6e1b-b09a-455e-bb48-39202c374430" class="responsiveMedia figure mediaLeft"> <img class="responsiveMedia__image figure__image" src="https://www.chesapeakebay.net/files/images/content/_900xAUTO_crop_center-center_100_none/06.17_groundwater_issues_image.jpg" srcset="https://www.chesapeakebay.net/files/images/content/_1800xAUTO_crop_center-center_100_none/06.17_groundwater_issues_image.jpg 2x" width="900" height="600" alt="Photo of slightly polluted water that will be absorbed by the ground below."><figcaption class="figure__caption"> Water rises just above the surface in Caroline County, Maryland. <span class="credit">(Photo by Chesapeake Bay Program)</span> </figcaption> </figure> <h2 id="overview">Overview</h2> <p>Drops of rain or snow that fall onto the land do not always wash straight into rivers or streams: instead, precipitation can seep through the soil and into groundwater. Groundwater can become contaminated when pollutants on the land seep underground, pushing nutrients and chemical contaminants into nearby waterways. In the Chesapeake Bay region, the slow pace of polluted groundwater flowing into the Bay results in a “lag-time” between the adoption of pollution-reducing practices and the positive effects those practices have on a particular river or stream.</p> <h2 id="what-is-groundwater">What is groundwater?</h2> <p>Water isn't just found on above ground: groundwater is water that can be found under the earth’s surface, stored in the cracks and spaces between particles of soil, sand and rock. Precipitation can recharge groundwater supplies: rain and melting snow soak into the ground and travel downward to reach solid, impermeable bedrock. Here, groundwater stops moving downward and starts saturating the surrounding soil, forming an area known as an aquifer.</p> <p>Groundwater comes to the earth’s surface when it flows through a spring or into rivers, streams and lakes. Scientists with the U.S. Geological Survey (USGS) have <a href="http://pubs.usgs.gov/fs/fs15099/">found</a> that in an average year, almost 27 of the 50 billion gallons of streamflow that enter the Chesapeake Bay come from groundwater.</p> <p>By drilling wells into underground aquifers, groundwater can also be extracted from the earth for human uses. Much of our groundwater is used to irrigate crops, and more than half of the United States relies on groundwater for drinking water. But communities can face water shortages when groundwater is used faster than it is replenished.</p> <p>USGS scientists <a href="https://www.chesapeakebay.net/news/blog/groundwater_withdrawal_causing_land_to_sink_in_lower_chesapeake_region">found</a> that the withdrawal of groundwater in the lower Bay region has caused the land to sink, worsening the effects of sea-level rise and increasing the severity of floods along the Delmarva Peninsula and Virginia Coastal Plain.</p> <h2 id="how-do-pollutants-reach-groundwater">How do pollutants reach groundwater?</h2> <p>Groundwater can become contaminated when pollutants on the land seep into underground aquifers. A number of human activities can pose a threat to groundwater, including:</p> <ul><li>leaking or damaged storage tanks of gasoline or oil,</li><li>abandoned containers or uncontrolled spills of hazardous waste,</li><li>fertilizers, pesticides or road salts applied to lawns, fields and roads, and</li><li>leaking landfills and septic systems.</li></ul> <h2 id="how-is-polluted-groundwater-harming-the-chesapeake-bay">How is polluted groundwater harming the Chesapeake Bay?</h2> <p>When contaminated groundwater comes to the surface, it can pollute rivers and streams. In our watershed, polluted groundwater often pushes <a href="https://www.chesapeakebay.net/issues/threats-to-the-bay/nutrient-runoff">nutrients</a> and <a href="https://www.chesapeakebay.net/issues/chemical_contaminants">chemical contaminants</a> into the Chesapeake Bay. Several studies have found that the slow movement of polluted groundwater into the Bay is lengthening the “lag-time” between the adoption of pollution-reducing practices and the positive effects of those practices on a particular river or stream.</p> <p>A USGS model showed that groundwater on the Delmarva Peninsula—and the excess nitrogen it can contain—takes an average of 20 to 40 years to flow through the area’s aquifers and into rivers and streams. This means that slow-moving groundwater could push nutrient pollution into the Bay even after we have lowered the amount of nitrogen and phosphorous we put on the land. In some parts of Delmarva, the groundwater that is now flowing into local waterways contains nitrogen linked to fertilizer used three decades ago.</p> <h2 id="what-you-can-do">What you can do</h2> <p>To lower the amount of pollutants seeping into groundwater, lower the amount of fertilizers, pesticides and road salt applied to your lawn and driveway, and ensure that storage tanks and septic systems are properly managed to avoid allowing gasoline, oil or wastewater to soak into the ground.</p> <aside class="callout callout--progress"> <h2 class="callout__title">Partnership goals<span class="appendedIcon">‍<img src="https://www.chesapeakebay.net/assets/images/progress-logo--icon.svg" width="84" height="37" alt=""></span></h2> <p>The Chesapeake Bay Program is committed to reducing nitrogen, phosphorus and sediment pollution through its <a href="https://www.chesapeakeprogress.com/clean-water/watershed-implementation-plans">2025 Watershed Implementation Plans</a>. As of 2023, the best management practices (BMPs) in place to reduce pollution are estimated to achieve 57% of the nitrogen reductions, 67% of the phosphorus reductions and 100% of the sediment reductions needed to attain applicable water quality standards when compared to the 2009 loads.</p> <a href="https://www.chesapeakeprogress.com/clean-water/watershed-implementation-plans" class="pageLink--inverse" target="_blank">Track our work at ChesapeakeProgress.com<span class="appendedIcon">‍<i class="fas fa-angle-right"></i></span></a> </aside> </div> <div class="l-twoColumn__asides" id="two-column-asides"> <aside class="panel loboOwl"> <h2 class="h4">FAQ</h2> <div class="ladder"> <details class="accordion"> <summary class="accordion__handle accordion__handle--link"><h3 class="u-step-0">What is groundwater?</h3></summary> <div class="accordion__body"> <p> Groundwater is water that can be found under the earth’s surface, stored in the cracks and spaces between particles of soil, sand and rock.</p> </div> </details> <details class="accordion"> <summary class="accordion__handle accordion__handle--link"><h3 class="u-step-0">How does groundwater become polluted?</h3></summary> <div class="accordion__body"> <p> Groundwater can become contaminated when pollutants on the land seep into underground aquifers.</p> </div> </details> <details class="accordion"> <summary class="accordion__handle accordion__handle--link"><h3 class="u-step-0">How does polluted groundwater affect the Chesapeake Bay?</h3></summary> <div class="accordion__body"> <p> Contaminated groundwater can push pollutants into the Chesapeake Bay. The slow movement of polluted groundwater into the Bay can lengthen the “lag-time” between the adoption of a pollution-reducing practice and the positive effect of that practice on a particular river or stream.</p> </div> </details> <div> <a href="/discover/faq" class="pageLink">More FAQs<span class="appendedIcon">‍<i class="fas fa-angle-right"></i></span></a> </div> </div> </aside> <aside class="panel loboOwl"> <h2 class="h4">Terms</h2> <div class="ladder"> <details class="accordion"> <summary class="accordion__handle accordion__handle--link u-bold">Aquifer</summary> <div class="accordion__body"> <p>A body of permeable rock that can contain or transmit groundwater.</p> </div> </details> <details class="accordion"> <summary class="accordion__handle accordion__handle--link u-bold">Bedrock</summary> <div class="accordion__body"> <p>Solid rock underlying the earth’s surface.</p> </div> </details> <details class="accordion"> <summary class="accordion__handle accordion__handle--link u-bold">Groundwater</summary> <div class="accordion__body"> <p>Water that is stored under the earth’s surface, in the cracks and spaces between particles of soil, sand and rock.</p> </div> </details> <details class="accordion"> <summary class="accordion__handle accordion__handle--link u-bold">Lag-time</summary> <div class="accordion__body"> <p>The span of time between the adoption of a pollution-reducing practice and the visible effects of that practice on a particular waterway.</p> </div> </details> <details class="accordion"> <summary class="accordion__handle accordion__handle--link u-bold">Nutrients</summary> <div class="accordion__body"> <p>Chemicals that plants and animals need to grow and survive but, in excess amounts, can harm aquatic environments. Elevated levels of the nutrients nitrogen and phosphorous are the main cause of poor water quality in the Chesapeake Bay.</p> </div> </details> <details class="accordion"> <summary class="accordion__handle accordion__handle--link u-bold">Pesticides</summary> <div class="accordion__body"> <p>A general term that describes the chemical substances used to destroy or control insect or plant pests. Many pesticides are manufactured and do not occur naturally in the environment. Others are natural toxins that are extracted from plants and animals.</p> </div> </details> <div> <a href="/discover/glossary" class="pageLink">All Terms<span class="appendedIcon">‍<i class="fas fa-angle-right"></i></span></a> </div> </div> </aside> <aside class="loboOwl" style="--mt:8"> <h2 class="h3">Related Issues</h2> <div class="xScroll xScroll--cards xScroll--cancelForTabletUp"> <div class="xScroll__items"> <article class="card card--cta xScroll__item"> <div class="card__body"> <h3 class="card__title"> <a href="https://www.chesapeakebay.net/issues/threats-to-the-bay/chemical-contaminants" class="card__link">Chemical Contaminants</a> </h3> </div> <figure class="card__imageCont"> <img class="card__image" src="https://www.chesapeakebay.net/files/images/content/_431x287_crop_center-center_none/06.17_chemicalcontaminant_issues_image.jpg" width="431" height="287" srcset="https://www.chesapeakebay.net/files/images/content/_862x574_crop_center-center_none/06.17_chemicalcontaminant_issues_image.jpg 2x" alt="Chemicals are seen in the water." /> </figure> </article> <article class="card card--cta xScroll__item"> <div class="card__body"> <h3 class="card__title"> <a href="https://www.chesapeakebay.net/issues/whats-at-risk/rivers-and-streams" class="card__link">Rivers and Streams</a> </h3> </div> <figure class="card__imageCont"> <img class="card__image" src="https://www.chesapeakebay.net/files/images/content/_431x287_crop_center-center_none/06.17_rivers_issues_image.jpg" width="431" height="287" srcset="https://www.chesapeakebay.net/files/images/content/_862x574_crop_center-center_none/06.17_rivers_issues_image.jpg 2x" alt="A wide river lined by forest." /> </figure> </article> <article class="card card--cta xScroll__item"> <div class="card__body"> <h3 class="card__title"> <a href="https://www.chesapeakebay.net/issues/threats-to-the-bay/stormwater-runoff" class="card__link">Stormwater Runoff</a> </h3> </div> <figure class="card__imageCont"> <img class="card__image" src="https://www.chesapeakebay.net/files/images/content/_431x287_crop_center-center_none/06.17_stormwater_issues_image.jpg" width="431" height="287" srcset="https://www.chesapeakebay.net/files/images/content/_862x574_crop_center-center_none/06.17_stormwater_issues_image.jpg 2x" alt="Storm drain sends water into a road, which will lead to the Bay." /> </figure> </article> </div> </div> <div> <a href="/issues" class="pageLink">View All Issues<span class="appendedIcon">‍<i class="fas fa-angle-right"></i></span></a> </div> </aside> </div> </section> </article> </main> <footer class="footer"> <div class="footer__callout"> <div class="contentContainer"> <h2 class="footer__calloutHeader">Connect with us. 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