Water Works 2 - 3/7/03

Scope of the Problem and Aquifer Fundamentals

In our previous episode we alleged that the New Jersey Department of Environmental Protection has permitted the pumping of nearly all the groundwater that should recharge the aquifer at the headwaters of Lockatong Creek, near Quakertown. The state has also allocated all water supplies available to high-capacity users for the entire Lockatong Creek watershed from the creek’s headwaters alone, according to the NJDEP’s own Water Supply Master Plan.

The NJDEP now proposes to allow an additional 53 million gallons of water to be pumped each year where it has already inflicted considerable damage to both the aquifer and the creek.

These are serious charges, so proofs are in order. Before we explore the NJDEP’s own memos and correspondence to learn how it created the problem we’re facing, let’s review some basic hydrology, to show you what it has done and what its proposed 53 million gallon allocation increase really means.

The aquifers most of us use in Hunterdon County for drinking, watering crops or other purposes are replenished by rainfall that seeps into formations of rock underground. The rock formations that store rainwater in the Lockatong basin replenish very slowly and hold very little water. Almost all the rain that seeps into them does so only twice every year, in late fall and early spring. Of the 42-46 inches of rain that fall on any acre of land here annually, only 2-4 inches make it into our aquifer. Those are standard numbers known as our aquifer’s “recharge rate.” (i)

That 2-4 acre-inch per year recharge rate makes Quakertown’s one of the worst performing water supplies in New Jersey. Groundwater studies indicate that recharge rates for Lockatong bedrock aquifers like ours run as low as 1 acre-inch per year, or as little as 2.5% of all rainfall. (ii)

Now for some math. Using the highest estimate of recharge, as a courtesy to the NJDEP, if an acre-inch of water equals approximately 27,500 gallons, that means a 2-4 inch recharge rate allows between 55,000 and 110,000 gallons of water to migrate into the aquifer annually through any single acre of land underlaid by Lockatong shale. The tract of land for which the NJDEP is proposing its 53 million gallon per year allocation increase has an existing annual allocation of 96 million gallons, for a combined total of 149 million. (iii) At the generous 110,000 gallon recharge rate, it takes 2.1 square miles of land to replace 149 million gallons of water each year in our aquifer and 1.4 square miles of land to supply enough water for the NJDEP’s existing 96 million gallon allocation. Expressed in acres, that’s 1,355 and 873 acres, respectively.

The NJDEP has only one problem. The tract of land for which it is proposing this allocation totals only 163 acres, and it has done the same thing in several other locations nearby, where it has managed to allocate a total of 337 million gallons of water per year to high volume users in an area of only 5 square miles. (iv)

On a county map, imagine a circle centered in Franklin Township, bordered by Quakertown to the north and Oak Grove Road to the south, and extending slightly past Route 615 to the west and Route 579 to the east. The area of that circle is 5 square miles. The headwaters of the Lockatong are where the bull’s-eye should go in your imaginary ring and the annual recharge for the entire target is only 348 million gallons of water per year. (Map)

Put another way, the amount of water the NJDEP has already allocated within that circle is 97% of its total aquifer recharge. The NJDEP’s own Water Supply Master Plan sets the safe maximum for water allocations at 20% of recharge, which means the NJDEP has allocated 4.8 times more water there than it should have. Factor in other real world values like “impervious coverage,” and use something lower than the most optimistic recharge rate, and you put the current allocation rate as high as 10 times the state’s safe limit.

Next, we will assess the damage the NJDEP has inflicted and look at what it did when it knew it had created a problem.

Ron Gutkowski