The creek weir is a constant pain. The creek eroded the bank adjacent to the weir a bit so I've reinforced with some sapling poles hammered into the creek bed along the bank.
After years of maintaining rock lined low water crossings we use to get tractors and equipment across small seasonal creeks, one thing I have learned is the need to run the rock up each side of the bank far enough to force the water to stay within the rock lining. If you just fill up a ravine with rock, it works for the time being. But as soon as there is significant rain the water will wash out around the edge of the rocks and make the ravine wider.
So if you can with your weirs, extend the rock in a U shape up the bank so that as the water flows over it it can not get to the banks edge to wash out around the rocks.
Although your weirs are not technically a pond, I have included this thread in my unofficial list of
Specialty ponds.
