Other drops hit farmland, absorbing fertilizers. Eventually, these nutrient-rich drops find their way into the Bay's tributaries. However, drops of rain that fall today may not make it into those tributaries or the Bay for five years or more. This natural, slow process by which water travels on land is called groundwater lag time. For example, runoff from storm events can infiltrate the ground before reaching a stream, can move with groundwater, then can eventually seep back into streams, rivers and the Bay.
Lag time can have an impact even when there's no precipitation.
In the Bay watershed, several cities and towns use groundwater as a source for their public water supplies. During times of drought, a lack of precipitation eventually disrupts supplies of groundwater. Any actions to reduce the amount of nutrients in the air and on land will help. This is another reason to help protect and restore streamside forest buffers in the Bay region.