Significant rain in the Main Divide headwaters of the Rangitata and Waitaki rivers, coupled with heavy nor-westerly overspill rain falls in the foothills, has seen Environment Canterbury issue flood warnings for several rivers in the region.
On Sunday at 6.20am the fuse plug in the weir below the Opuha Dam began operating after the water levels in the dam reached their maximum level of 392.2m before spilling. The increase in water levels downstream in the Opuha River due to the fuse plug becoming operational was expected to be between 0.5m and 1m in the gorge. This higher water level was expected to be at Skipton Bridge by between 8am-8.30am and was due to reach Raincliff at about 11am today.
The fuse plug is designed to release during heavy flows to protect the main Opuha Dam structure and has operated in this way during floods before.
ECan’s South Canterbury flood controller Graham Sullivan says no problems were anticipated from these high flows in the narrow Opuha Gorge section between Skipton and Raincliff. Below this point, the river broadened out and again, no problems at all were expected here or in the Opihi River into which the Opuha flows.
Elsewhere in the region the Rangitata River was expected to peak at about 1600-1700 cumecs at Klondyke at about 10am and the mouth at about 5.30pm-6pm.
The Waitaki River was flowing at about 1200 cumecs at 8am. This flow may reach as high as 1800-2000 cumecs later this afternoon or tonight.
The heavy rainfall in the Southern Alps, combined with snow melt and an already wet catchment have combined was responsible for the high levels of the rivers, Mr Sullivan said.
In the Mackenzie Basin, the Omarama Stream at Tara Hills was recorded at 23 cumecs at midnight and has held that level for the last seven hours. There is extensive surface flooding including around the camping ground and the Omarama golf course due to the stream breaking at several points. Mr Sullivan said the camping ground had had to be evacuated. The Ahuriri River peaked at 351 cumecs at 6am this morning and was expected to slowly recede.
“The public and river users are advised to take care near all South Canterbury rivers, especially those that are rising fast or flowing swiftly,” Mr Sullivan said.
Keep an eye on the flood alerts right hand side ECan homepage or check river levels on the ECan website also www.ecan.govt.nz/Our+Environment/Water/Rivers/RiverFlows/river-flow-table.htm also accessible from the front page under the flood alerts box.
For urgent calls, speak to the ECan media advisor: 027 221 5259