■ By Matt McPherson / Columnist
The series of water retention basins constructed in the late 1940’s alongside the San Jacinto River play a critical role in sustaining storm flows to replenish our groundwater today. Known as the “upper basins,” both their numbers and retention capacities have been expanded in recent years to accept not only local surface water, but higher-quality imported “northern water.”
The recent week-long siege of welcome rain brought the river to a point where water could be diverted into the “settling ponds’ and, in so doing, the normally routine practice turned into a disaster Sunday. It appears that the water diverted from the river overran the berm of one of the bigger basins, which overwhelmed and cut through the half dozen smaller downstream basins one after the other. The probable cause of this “domino effect” was floating debris that gathered around the screen in front of the large basin’s transfer pipes.
The sand and soil levees that define and separate the basins can be repaired as soon as the Valle Vista retention ponds are able to support trucks and grading equipment.