Southern California Groundwater: More Than Meets the Eye

By Artun Ereren

When driving on the freeway, I occasionally look over to my left or right to a sight of a dried up Santa Ana River.  Before I started my Water education, I always thought the Santa Ana River was a remnant of the past- an empty reminder that Orange County had once had much more abundant water supply. Upon further research I’ve learned that there is more than meets the eye. Snowpack from the Chino Hills Mountains provide the starting point of the Santa Ana River, since California has been a near two decade drought the snowpack has been limited and therefore has effected the Santa Ana River’s natural supply. Luckily, Orange County has never heavily relied on the Santa Ana River as a key drinking water source.  Orange County’s groundwater aquifer is the key supply, a source that is naked to the eye yet we rely on looking at the Santa Ana River as a measure of abundance. So what exactly is the connection between the Santa Ana River and groundwater aquifer?

The Santa Ana River actually plays a crucial role in Orange County’s groundwater management.  The dried up river beds that we all see are actually recharge basins used to fill groundwater aquifers. In Anaheim, there are sedimentation basins that where the Santa Ana River or incoming rainfall, percolate into the river bed and eventually into the grand groundwater aquifer. Of course Orange County sacrifices the aesthetic of a healthy river, but the groundwater recharge that the Santa Ana River provides is a safe and reliable source for Orange County residents. The Orange County Water District transformed the functionality of the Santa Ana River into a more integrated tool with other sources, for example the Groundwater Replenishment System is globally known for taking treated, potable recycled water and injecting it back into the groundwater aquifer, functioning as Orange County’s “drinking water bank”. 

Water agencies not just in Orange County but also all along the California coast recognize groundwater as a precious resource. Along with agricultural chemical runoff, seawater intrusion from the Pacific Ocean is a serious threat to the health of a groundwater aquifer. Water agencies inject pure water into what they call “seawater intrusion wells” to serve as a buffer between the ocean and groundwater aquifer. The great lengths that water managers go to protect the groundwater is a reflection of how important of source groundwater really is. The lesson here is that when thinking about water there is always more than meets the eye. The beautiful Pacific Ocean is also an unseen nightmare to our groundwater, yet at the same time the dried up rivers also have an important place in how we get our water.