Domestic Water II - Deep Wells

The deep aquifers beneath Northumberland County are at depths of between about 200 and 900 feet. Water quality is good to excellent as long as the well casing is not cracked or broken. About 75% of the people in the County derive their water from either private or public drilled (artesian) wells, and the most common water quality problem is high sodium content. Individuals with blood pressure problems should have their water analyzed for sodium and discuss the results with their physician. The critical problem with this source of water is not quality, but that the supply of potable water is finite.

The water we pump from deep wells once fell on the Northern Neck east of Fredericksburg, and slowly percolated down, across several relatively impermeable layers (confining layers, or aquitards), all the while flowing eastward (seaward) at depths of hundreds of feet. This is a slow process, and thus the water we use today is many thousands of years old. Although abundant rain still falls in the recharge area today, we are pumping the water out of the deep aquifers faster than Nature can replenish it. For example, the level of water in wells at Montross and Kilmarnock, (the closest wells to Northumberland County for which long term monitoring data exist) have declined between 37 and 40 feet in 31 years of measurements. The situation is actually much worse, because many wells in the Northern Neck once discharged water at the land surface, based on local remembrances. Prior to extensive drilling in the last century, the deep aquifers were "full to the brim", with the "brim" being the elevation of the land surface east of Fredericksburg. Because the tops of wells in Northumberland County are at lower elevations than the "brim", water could flow out of our wells under pressure. This “artesian” flow stopped about the middle of the last century, soon after deep drilling became commonplace. Thus it is certain that water levels in deep wells have fallen more than100 feet since the middle of the last century. At Montross, the top of the aquifer is at about 400 feet and the water level in the monitoring well is currently at about 170 feet. Hydro geologists recommend that aquifers never be dewatered or else they will be irreparably damaged. Thus we have sufficient information to permit crude estimates of how long the water should last. 400 – 170 = 230 feet of water remaining / 37 feet of decline in 32 years of actual measurements = about two centuries. Or, 230 feet of water remaining / 170 feet of decline in about 50 years = by 2100.

Lowering of water levels in deep wells is a regional phenomenon. Thus we can be quite sure that water levels are declining about 1.5 foot each year beneath Northumberland County, despite that fact that we have no systematic measurements within the County itself (although we need them! Please help us find wells that can be monitored on a regular basis). Because of the regional nature of our deep aquifers, large withdrawals of water in surrounding counties, including counties in Maryland, affect local water levels. It is common sense that the largest users (industry and large municipalities) are the cause of most of the regional water level decline.

Declining water levels in deep wells is not the only concern. Saline (ocean) water is intruding from the east and from strata below our deepest aquifers as the fresh water is pumped out. Our water increases in salt content the deeper we drill. "Saline intrusion", or increasing salt content in wells over time, is not just a theoretical prediction, but can be documented in wells near the coastline, in Virginia Beach, for example. Babies born today will live to see more frequent instances of wells going dry or becoming salty as we continue to deplete our deep groundwater reserves at today's rate of pumping. As the population of the County increases, and demand for water increases, the situation can only worsen unless we take action.

We obviously need to begin to conserve our water, with emphasis on the largest consumers. Less water passing though our septic systems or municipal plants also results in less pollution of our groundwater and our waterways. Potential actions we can take, in addition to conservation, include:

- Impound water in reservoirs and install treatment and distribution systems, at least to replace industrial and municipal wells (benefiting recreation in the process).

- Install desalinization or reverse osmosis systems in our homes.

- Harvest rainwater directly for at least part of our needs.

- Place further demands on our locally contaminated, shallow aquifer.

- Use multiple sources of water so that we don’t waste potable water to flush our toilets.

Do we have the will to address this problem now, which will not affect many of us in our lifetimes, but which will certainly affect future generations?