For example, the Yarkon spring dried up after previously flowing at 220 Mm 3 /a, and the flow of the Taninim spring declined from 110 Mm 3 /a to 30 Mm 3 /a. Artificial recharge volumes have ranged from a maximum of 62 Mm 3 /a to a minimum of 4 Mm 3 /a, depending on the availability of source water. On average, 26 Mm 3 /a, or 7.5 percent over and above the average natural replenishment, was recharged over the 23 year period to 1993. Clogging in recharge boreholes occurs due to silt build-up and algae in the source water, but this is adequately managed by back-flushing (pumping) the injection boreholes.