Governor Phil Murphy • Lt.Governor Sheila Oliver
NJ Home | Services A to Z | Departments/Agencies | FAQs  
State of New Jersey Department of Environmental Protection-Watershed Restoration
State of New Jersey Department of Environmental Protection
DEP Home | About DEP | Index by Topic | Programs/Units | DEP Online 

Water. It's an essential part of our lives. We use it to drink, to cook, to bathe and to clean. It's used by industry and businesses to manufacture their products. Farmers and gardeners use it to water their crops. Fish live in it and other animals depend on it for their survival.

The Earth has a phenomenal amount of water - approximately 1.4 quintillion cubic meters of it. Yet, of all that water, only a very small fraction is usable fresh water. About 97% is in the oceans - usable for fishing, swimming and transportation. It is too salty for drinking, irrigating our crops, or most industrial uses. Of the remaining 3% that is freshwater, about 2.997% is inaccessible: either frozen in the polar ice caps, or glaciers, or buried so deep as to be unavailable at affordable costs. Only about 0.003% of the total supply is easily available as soil moisture, exploitable ground water, water vapor, and lakes and streams.

New Jersey is home to over 18,000 miles of streams and rivers, over 3,500 lakes, reservoirs and ponds, over 700,000 acres of freshwater wetlands, and an extensive network of underground aquifers. Along the state's 127 mile coastline, there are over 200,000 acres of tidal wetlands. Using the national system of watershed-based hydrological units (HUCs), the state has 151 HUC-11 watersheds, which can be further subdivided into 970 HUC-14 subwatersheds. The average size of a HUC-14 subwatershed in New Jersey is 8.5 square miles.

On average, New Jersey experiences about 45 inches per year of rain or other forms of precipitation such as snow, sleet, or hail. However, about half of that water never gets to the state's elaborate system of surface and ground waters. Instead, about half of all precipitation goes directly back into the atmosphere, either immediately by evaporation, or through absorption into plants, which then transpire most of it.

Our dependence on water in our daily lives seems to grow. Back in medieval times, it has been estimated, each person used no more than 3 to 5 gallons per day. Today, Americans use, on average, about 1,500 gallons a day for our needs and comforts including food production, industrial supply, recreation and cooling.

Simple everyday items take vast quantities of water to be produced. For example, 24 gallons of water are needed to produce one pound of plastic. Fifteen hundred gallons are required to process a barrel of beer. Inside our homes, New Jersey residents use, on average, between 50 and 75 gallons of water per person per day.

Outside our homes, in order for an automatic lawn sprinkler system to apply one inch of water over a one acre lawn (the recommended weekly amount in dry weather), it will pump our 3,630 to over 7,000 cubic feet of water per day. That is the equivalent of somewhere between 27,154 and 52,363 gallons per week. This increasing demand for water and a growing population necessitates that we take every precaution to ensure a sustainable supply of clean water.



Sometimes, it seems too much precipitation happens too quickly, and a part of the State experiences devastating flooding. For example, portions of Burlington County received over a foot of rainfall on June 12, 2004. At other times, we get so little precipitation that our water supplies start to dry up and a drought emergency can be declared. For example, in 2001 the state received only 35.65 inches of precipitation, which was followed by below normal precipitation levels in the first nine months of 2002. This resulted in mandatory restrictions on water usage that lasted from March through November 2002.

In the mid-1960s, New Jersey experienced an ever worse drought; 35.15 inches fell in 1963, followed by 36.63 inches in 1964 and just 29.36 inches in 1965. In contrast, the wettest year on record, 1996, saw almost 60 inches (59.67") of precipitation fall on the state.



Water is everywhere - in the atmosphere, streams, lakes, rivers, the ground and our bodies. However, it should not be taken for granted. We hardly ever think about the fact that all the water in the world is somehow connected and much of it is continually moving. For millions of years, the same molecules of water have been constantly recycled and reused in various ways and places.

Since we want to be able to use good, clean water in many ways at various times and places, it is important to understand how water moves above, on, and below the Earth's surface. The water cycle, or hydrologic cycle, is the movement of our fixed supply of water as it is collected, cleansed and distributed through water bodies, plants, animals, land and the atmosphere.

The water cycle really has no beginning or end. However, to understand the water cycle, it is easiest to start with water vapor molecules in a cloud. Under suitable atmospheric conditions, those molecules will fall to the ground as some form of precipitation. In New Jersey, most of the precipitation comes as rain, but we also get water in the forms of snow, sleet and hail. When water molecules, such as raindrops, fall from the clouds, they might go in any several directions. Some are immediately absorbed by the ground or plants.

As part of the hydrologic cycle, water is returned to the atmosphere by evaporation from open water bodies and surface soils, and by transpiration from vegetation. These two components are often treated together and referred to as evapotranspiration. Even though we cannot see it happen, the processes of evaporation and transpiration occur continually. Evapotranspiration rates are greatest during the summer months because of higher temperatures and active growth of plants and trees. But these processes happen whenever the water is not frozen and plants are growing.

The water vapor from evaporation and transpiration forms clouds in the sky. In time, the vapor condenses and falls back to earth again as precipitation.

A sizable amount of rainwater runoff seeps into the ground to become ground water. Ground water moves into water-filled layers of porous geologic formations, called aquifers, which are underground areas where all of the spaces, or pores, between the soil and rock particles are filled with water molecules. The top of an aquifer is often referred to as the water table. Depending on the location, aquifers containing ground water can range from a few feet below the surface to several hundred feet underground. If the aquifer is close to the surface, its ground water can flow into nearby waterways or wetlands, providing what is called the base flow of a stream.

Contrary to popular belief, aquifers are not flowing underground streams or lakes. Ground water moves at an irregular pace, seeping from more porous soils, from shallow to deeper areas and from places where it enters the Earth's surface to where it is discharged or withdrawn.

Aquifer recharge areas are locations where rainwater and other precipitation seep into the Earth's surface to enter an aquifer. Aquifer discharge areas are locations, such as springs and artesian wells, where ground water becomes surface water. The bottoms of streams and lakes contain many aquifer discharge areas. A system of more than 100 aquifers is scattered throughout New Jersey. These aquifers cover over 7,500 square miles.

Ground water is the primary drinking water source for half of the state's population. Most of this water is obtained from individual domestic wells or public water supplies, which tap into aquifers.

Many farmers in New Jersey depend upon a steady supply of clean ground water to irrigate their crops. Ground water is also used by industry in manufacturing processes. Since it tends to be about 54 degrees all year round, ground water is often used in large air-conditioning systems and as non-contact cooling water.

If not absorbed by plants or the ground, or immediately returned to the atmosphere through evaporation, much of the rainwater flows overland into waterways, as stormwater runoff. In developed areas, some of this"overland flow" occurs in underground pipes known as storm sewers.

Potential pollutants and other impurities can enter in different parts of the water cycle. As water returns to the Earth through the atmosphere in the form of precipitation, various impurities in the air are intercepted. When it reaches the ground, water contains both man-made and natural impurities such as carbon dioxide, dust and pollen.

As water runs its course on the land, it continues to collect or dissolve oxygen, nutrients, minerals, nitrates, phosphates, carbon dioxide, and other materials, most of which are necessary for plant and animal life. The types and amounts of materials vary according to the locations's geology, topography, vegetation, soil type, weather, water velocity and land use. Eventually, these collected materials are deposited in various parts of the water cycle before the water re-enters the atmosphere and continues to be recycled.



A watershed is the area of land that drains into a body of water such as a river, lake, stream or bay. It is separated from other watersheds by high points in the area such as hills or slopes. It includes not only the waterway itself but also the entire land area that drains to it. For example, the watershed of a lake would include not only the streams entering into that lake but also the land area that drains into those streams and eventually the lake. In addition, the lake's watershed includes all of the land adjacent to the lakeshore from which stormwater runoff would flow into the lake.

A watershed can be as small as a backyard that drains to a pond or as large as the sections of New York, Pennsylvania, New Jersey and Delaware that drain into the Delaware River. However, very small watersheds such as those measuring a few acres are often referred to as "drainage areas" while very large watersheds such as the parts of New York, Pennsylvania, New Jersey and Delaware that drain into the Delaware River are called "drainage basins."

Watersheds come in all shapes and sizes. They cross county, state, and national boundaries. No matter where you are, you're in a watershed!



Where does the water that rains on your home go? After it leaves your lawn, street or sidewalk where is it headed? Does it flow downhill straight to a nearby stream or lake? Does it wander into wetlands? Does it puddle in your backyard? Does it zip down a storm drain to a local creek? That destination, whether it's a puddle, a pond, a bay or a lake, is your watershed address. It could be Duck Pond, Spring Lake, Millstone River, Barnegat Bay or Beaver Brook.

Just like there are towns within counties within states, there are subwatersheds within watersheds within drainage basins. For example, the rain that falls on your driveway might flow into Lake Hopatcong, which flows into the Musconetcong River, which flows into the Delaware River. So your watershed address would be Lake Hopatcong, Musconetcong River, Delaware River even though your mail finds you through Jefferson Township, Morris County, New Jersey.



The type of land use (e.g., forest, agriculture, suburban, urban) and its associated activities can have a direct impact on the water quality of the watershed. When it rains, stormwater carries with it the effects of human activities as it drains off the land into the local waterway.

Forested areas are generally able to absorb more precipitation with less runoff than any other type of land use. Likewise, cultivated farm fields can absorb more precipitation than suburban lawns. The development of such open lands has a great effect on local water resources. It changes how both surface and ground water flows in the watershed and what flows in the water. The porous and varied terrain of natural landscapes like forests, wetlands and grasslands trap rain water and snow melt and allow it to slowly filter into the ground. Runoff tends to reach receiving waters gradually.

When farmers cultivate their fields, they create lots of pore spaces in the soil and small irregularities on the soil surface in order to increase the land's ability to absorb rainfall and thus reduce runoff.

As a watershed becomes developed, the forests and fields are replaced with impervious surfaces (roads, rooftops, parking lots and other hard surfaces that do not allow stormwater to soak into the ground). Without the plants to store and slow the flow of stormwater, the rate of stormwater runoff is increased. Less stormwater soaks into the ground because the sidewalks, parking lots and rooftops block this infiltration. Since less water infiltrates to ground water, a greater volume of water flows overland to the nearest waterway. This water also reaches the waterway faster because the impervious surfaces tend to be smoother and less resistant to flow than natural surfaces. This in turn leads to more flooding after storms and reduced flow in streams and rivers during dry periods.

The reduced amount of infiltrating water results in lowered ground water levels. This is reflected in less ground water recharge into the local waterways that depend on such recharge for their base flows between rainfalls.

Development within a watershed can have negative effects on the watercourse itself. During and immediately after storm events, the increased rates and volume of runoff mean that there is a lot more water flowing in the stream and it is flowing faster. The force of this moving water can cause more erosion of the stream banks and scouring of channels to occur. This in turn degrades habitats for plant and animal life that depend on clean water.

Sediment from eroded stream banks clog the gills of fish and blocks the light needed for plants. The sediment settles to fill in stream channels, lakes and reservoirs. This also increases flooding. These effects can be seen when as little as ten percent of a watershed is developed.



In addition to the high flows caused by urbanization, the increased runoff also contains additional contaminants (e.g., litter, cigarette butts and other debris from sidewalks and streets, motor oil poured into storm sewers, heavy metals from brake linings, settled air pollutants from car exhaust, and pesticides and fertilizers from lawn care). These contaminants reach local waterways quickly after a storm.

The type of pollutant a water droplet might pick up on its way through a watershed or aquifer depends in part on how the land it travels through is used. The severity of nonpoint source pollution appears to be proportional to the state's population density and distribution, the intensity of local agricultural activities, other land uses, and changes in land use.

New Jersey's population is unevenly distributed, with most people living in the northeastern counties, near Camden and along the Jersey Shore. It is these more densely populated regions where NPS problems are prominent, although signs of it can be found statewide.

Nonpoint source concerns in these densely populated areas center on pesticides and fertilizers from lawns and gardens, pet waste, litter, household hazardous waste disposal and motor oil and other chemicals from roadways. The discovery of these materials in the State's waterways is sometimes referred to as "people pollution."

New Jersey's more rural counties, famous for produce, dairy products and horses, also suffer from NPS symptoms. These agricultural areas have concerns with animal waste, fertilizers, pesticides, and sediments, as well as those forms of people pollution associated with urban areas.

The type of NPS problem a waterway experiences depends on the type of land use in its watershed. The same is true for an aquifer and nonpoint sources in its recharge area. Pollution prevention reduces the impact of these land uses in a watershed. By following the suggestions in this booklet, you can not only have a positive impact on your local stream or lake but also on the river, bays and ocean downstream.



Conserving water through efficient water use can help prevent nonpoint source pollution. Diverting less water from waterways or aquifers leaves more water in streams or lakes, protecting existing ecosystems such as wetlands (which absorb certain types of nonpoint source pollution.)

Water conservation can also save money by reducing pumping and treatment costs both before water reaches your home and after it leaves. Reduced water use may extend the life of existing treatment facilities and costs much less than developing a new water supply.

Remember to conserve water at home and work.
Here are a few ideas:


  • Install a toilet dam in your toilet tank
  • Install a water efficient showerhead and low flow toilet.
  • Turn off the faucet while brushing your teeth, and save 4 gallons a minute. (That's 200 gallons each week for a family of four.)
  • Keep showers under 5 minutes and save 1,000 gallons per month.
  • Fix dripping faucets and leaking toilets.
  • Run dishwashers and washing machines only when full.


  • Water outdoor plants in the morning or evening to reduce evaporation losses.
  • Install a drip irrigation system in your garden.
  • Use drought tolerant or native plants in your landscaping.
  • Capture roof top runoff in a rain barrel and use it to water your garden.
  • Reuse water rather than discarding it, for example, divert used dishwater to your garden rather than down the drain.
  • Mow your lawn as infrequently as possible to help retain moisture.
  • Sweep sidewalks and driveways rather than hosing them down.
  • See chapter 6 for additional ideas about Lawn and Garden Care.

A watershed plan is a strategy and a work plan for achieving water resource goals that provides assessment and management information for a geographically defined watershed. It includes the analyses, actions, participants, and resources related to development and implementation of the plan. The watershed planning process uses a series of cooperative, iterative steps to characterize existing conditions, identify and prioritize problems, define management objectives, and develop and implement protection or remediation strategies as necessary.

Since the late 1980s, organizations and agencies have moved towards managing water quality by using a watershed approach, which includes stakeholder involvement and management actions supported by sound science and appropriate technology. The watershed planning process works within this framework to identify and quantify specific causes and sources of water quality problems. It also identifies water quality goals and specific actions required to solve those problems. For guidance on this process, go to

continue to Chapter 3: Managing the Flow of Stormwater
back to The Clean Water Book Table of Contents

back to top


Department: NJDEP Home | About DEP | Index by Topic | Programs/Units | DEP Online
Statewide: NJ Home | Services A to Z | Departments/Agencies | FAQs

Copyright © State of New Jersey, 1996-2019

Last Updated: July 11, 2018