Citizens expect sound land use policies based on what is in the best interest for everyone county-wide, not just based on one developer’s self-interest. We must have sustainable, available, good quality water for all residents. To do that we must plan to for sustainable water.
I am one of the estimated 50,000 in Prince William who depend on groundwater for my drinking water. When I replaced my pump this spring, I took the opportunity to have my static water level measured. The measured level was 43 feet below grade. Sixteen years ago when the well was installed the static water level was 30 feet below grade. The groundwater table is falling- 13 feet in 16 years. My neighborhood of 10 acre homes was built about 16 years ago. Groundwater levels can be affected by how many other wells draw from the aquifer, how much groundwater is being used in the surrounding area for agricultural, private or public supply, or how much groundwater is being recharged.
Sustainability of groundwater is hyper-local. Little is known about the sustainability of our groundwater basins in Prince William County, but potential problems are still at a manageable stage. We need to know if the current and planned use of our groundwater is sustainable even in drought years. We need to understand how ground cover by roads, parking lots and buildings will impact groundwater recharge and what level of groundwater withdrawals are sustainable on site to determine if a proposed change in land use or additional use of groundwater is sustainable before it is granted. We need to understand our groundwater and plan for sustainable water.
Development of an area can impact groundwater recharge. Land use changes that increases impervious cover from roads, pavement and buildings does two things. It reduces the open area for rain and snow to seep into the ground and percolate into the groundwater and the impervious surfaces cause stormwater velocity to increase preventing water from having enough time to percolate into the earth, increasing storm flooding and preventing recharge of groundwater from occurring. Slowly, over time, this can reduce groundwater supply and the water table falls.
The U.S. Geological Survey, USGS, maintains a group of groundwater monitoring wells in Virginia that measure groundwater conditions daily and can be viewed online. Only one of wells is within the rural area of Prince William County. It is in the northwest corner of the county. The land use around that well has not changed in decades. Daily monitoring data available from that well go back to 1968. What can be seen in the graph below is the slow decline in the water level after 2004. (The upward slope is feet below grade for the groundwater level.)Despite not experiencing any significant droughts since 2008 and having the wettest year on record in 2018. The decline is modest over this period compared to my well, but will continue and get worse over time especially if demand for groundwater is increased and impervious surfaces continue to grow, reducing recharge.
Water is essential for all present and future residents. Let’s make sure we have it.
Elizabeth Ward
https://greenrisks.blogspot.com/2019/11/study-groundwater-resources-before.html
https://greenrisks.blogspot.com/2019/11/the-rural-crescent-may-not-always-have.html