Thursday, January 12, 2017

Liveblogging the Deluge: Following Up on the Dry Creek Flood

Dry Creek in Modesto flooded to the greatest extent in two decades yesterday, with peak flows exceeding 6,000 cubic feet per second. I was out documenting the flood surge, and I managed to get to the Dry Creek Trailhead ahead of the high water around 4:30 or so. The water was rising but as you can see in the picture above, it had not breached the small levee that kept the river in the channel. I know from other reports that the flood hit a short time after I left.
I was out early this morning, and though the peak of the flood had passed hours earlier, the flow was still high, about 4,000 cubic feet per second, and there was a lot of water covering the flood plain. It was an impressive sight.
Now that the flows in Dry Creek are receding, the dam operators at Don Pedro Reservoir will probably start ramping up their releases from the lake. The goal is to keep flows in Modesto to 9,000 cfs or less to prevent flood damage. The reservoir has been accumulating water with inflows around a high of almost 45,000 cfs to the current 26,000 cfs. The lake stands at 812 feet, or 1,805,600 acre-feet, and has risen 26 feet since the beginning of the storm sequence. Since the lake will fill at 830 feet (2,030,000 acre-feet), it is now at 89% of capacity, and more than 130% of average for this time of year. They will need to free up more space for additional storms and spring runoff


Anonymous said...

Is there a reason New Melones reservoir is only at 35% of capacity while nearby Don Pedro is at 89%?

Garry Hayes said...

New Melones Dam has a greater capacity (2.4 million acre-feet), but the river that feeds it is smaller than the Tuolumne. During the peak of the storms last week, 24,000 cfs were flowing into New Melones, while somewhere between 45,000 and 65,000 cfs were flowing into Don Pedro. That's my understanding. Wouldn't mind hearing from others.

Anonymous said...

I'll buy it. It looked like Tuolumne had a larger watershed, or maybe higher elevation watershed which gathered more snow/rain, but wasn't sure.