Water Reuse:  A Strategy to Protect Our Natural Resources

Water reuse becomes a sound solution to multiple water resource related issues as nutrient reduction regulations are implemented, TMDL’s are developed and implemented, water supply plans are mandated, ground water resources become limited, new potable water resources become increasingly difficult to develop, and economic development pressures grow. 

How It Helps the Bay
Water reuse is one of the most environmentally beneficial ways to keep the Chesapeake Bay healthy and viable now and in the future.
The Chesapeake Bay is the largest and most biologically diverse estuary in North America.  A complex ecosystem that supports more than 3,600 species of fish, birds, plants, and animals, the Bay and its 100,000+ tributaries have served as commercial and recreational resources since before the English first settled here 400 years ago.

But more than four centuries of human activity have damaged the Bay’s fragile environment.  To protect and restore the Bay’s ecosystem, several states, including Virginia, joined with the U.S. Environmental Protection Agency (EPA) in the early 1980s to create the Chesapeake Bay Program.  A vital component of this program is to improve water quality by reducing nutrient loads to the Bay. 
In HRSD’s region, treated wastewater is discharged to the Chesapeake Bay and its tributaries.  This wastewater contains nutrients, including nitrogen and phosphorus.  Both of these are essential macronutrients required to support all forms of life.  However, in excess, they can degrade the Bay’s ecology and environment.  Treated effluents are not the only source of nitrogen and phosphorus discharged to the Chesapeake Bay.  Other potential sources may include storm water runoff, ground water, cooling water, agricultural runoff, and air deposits.  Of these discharges to the environment, treated wastewater effluent often represents the first choice for nutrient control because it is the easiest to regulate. 

To begin reducing these nutrients, each point source in the states participating in the Chesapeake Bay Program is assigned maximum allowable discharge loads.  These loads, or caps, of nitrogen and phosphorus are expressed as pounds per year that can be discharged.  The caps are determined by wastewater flow and the concentration of the particular nutrient discharged.  Currently, the lowest nutrient concentration any wastewater plant can theoretically achieve is called the “Limit of Technology” or simply LOT.  These limits are currently defined as 3.0 milligrams per liter for total nitrogen and 0.3 milligrams per liter for total phosphorus.  The limits are achievable only by employing expensive to install and maintain, state-of-the-art treatment technologies that are being required by Virginia to assist in improving the health of the Bay. 

Water reuse can play a powerful role in the reduction of nutrient discharges.  For example, all plants need nitrogen and phosphorus to grow--the same nutrients that need to be reduced from wastewater discharges.  Using nutrient-rich reclaimed water in agricultural, horticultural, and forestry irrigation applications prevents the nutrients from entering the Bay while providing the following positive outcomes:  directly and beneficially using the nutrients in reclaimed water to promote desired plant growth, reducing the use of commercial fertilizers, and meeting the plants’ moisture requirements.  As a direct result these previously unwanted nutrients are used beneficially.  

How It Saves Our Precious Drinking Water
Using reclaimed water to help meet current and future non-potable water needs increases the available water supply without the expensive and time consuming task of developing new resources or obtaining more of the already threatened ground water supply.  Thus we extend the life of our present and future drinking water supplies, which are finite resources.  This is good business and it makes sense.  We expand that supply by shifting the demand for non-drinking (non-potable) needs to an alternative supply like reclaimed water.  This saves high-quality drinking water for purposes absolutely requiring that resource.

How It Conserves Ground Water
Ground water is another valuable but finite resource that provides water for drinking, irrigation, and industrial uses.  Regulatory agencies set withdrawal limits to prevent ground water supplies from being depleted faster than they can be replenished.

These limits are especially important in the HRSD service area located east of Interstate 95 and south of the Mattaponi and York Rivers. Much of this region has been classified as a Ground Water Management Area (GWMA).

In a GWMA, ground water withdrawals of more than 300,000 gallons per month require a permit from the Virginia Department of Environmental Quality (DEQ).  Many assume this permit requirement only affects major ground water users.  However, if you have a three-acre lawn or garden plot and you plan to use ground water for irrigating at a minimum rate of one inch per week, you will use 325,848 gallons per month.  (One acre inch is 27,154 gallons per acre per week.  A three-acre plot requires 81,462 gallons per week and 325,848 gallons per month.)  Therefore, fulfilling this relatively small irrigation need requires a ground water withdrawal permit.

Reclaimed water offers a proven, safe, and environmentally friendly alternative for irrigation.  Florida, California, and Texas have irrigated with reclaimed water for decades with many positive measurable effects on crops and plants and no adverse effects detected on ground water quality.  Irrigating with reclaimed water adds valuable essential nutrients like nitrogen and phosphorous.  This reduces the need for commercial fertilizer applications and reduces the possibility of nutrient loss in surface runoff.

Using reclaimed water for non-potable needs such as irrigation and industrial uses helps reduce the demand on Virginia’s ground water aquifers and extend the quantity of this drinking water source well into the future.

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