Aquifer Levels and Quality
Last updated 5/15/2018 at 11:14am
In order for Borregans and water administrators to get both a good handle on how much our groundwater table is lowering (and how fast), plus assess trends in water quality around the Borrego Sub-basin as such lowering occurs, our BWD and its technical consultants continue to update the information (and used for this article).
They are acquiring more accurate information as we prepare to enter into the 2020-2040 operational phase of our Groundwater Sustainability Plan (GSP) to be drafted in early 2019.
With 20 years to reach State-mandated sustainability of our only source of water - our aquifer system – the need to accurately measure both water quantity and water quality to establish baselines for future decisions is obvious. But we need data, and as much as we can get.
As a single reference point for future checks on where the water table is, the elevation of Christmas Circle is 597 feet above sea level, and the top of the water table in that general area is currently about 200 feet beneath it.
Our Borrego Springs Sub-basin is divided into North, Central, and South Management Areas (MA’s). Within each MA, groundwater elevation is measured by a current total of 36 monitoring wells.
Agriculture dominates the North MA, where six wells provide groundwater level data; municipal supply dominates the Central MA where 16 wells provide monitoring data; and 14 wells in the South MA (the area surrounding Rams Hill and Casa Del Zorro) have 14 monitoring wells.
Current evaluation of data by BWD technical consultant Dudek, Inc. reveals the water table dropping historically by about 2.5 to 3 feet per year in the North MA. In the Central MA, the lowering of the water table is slightly less, between 1.17 to 1.85 feet per year. And in the South MA, a monitoring well in the Borrego Sink far away from pumping centers reveals a drop of only about half a foot per year.
At Rams Hill, there is a more complicated picture of historical and current groundwater levels, with one area shown as actually recovering, while at another area the water table appears to receding at a faster than average rate compared to North MA and Central MA rates.
According to the Dudek report, “The groundwater trend at Well MW-3 in the (South MA) reflects the change in water supply for the Rams Hill Golf Course. Prior to 2013, the Rams Hill Golf Course was predominantly supplied from wells located in the (Central MA).
Groundwater levels are observed to be recovering at a rate of 1.34 feet per year in well MW-3 over the 10-year period from 2004 to 2014.
Full story in the May 17 issue of the Borrego Sun.