Placement of interlocking A-jacks and bank grading 



tale indicators of water quality in a stream, but 

 they're not all created equal. Tough-shelled and 

 hardy, crayfish are more tolerant of silt and 

 pollution, yet they still need water of average 

 quality. Porous-skinned amphibians are more 

 delicate and frequent even cleaner water. Fish such 

 as trout and insects such as mayflies and stoneflies 

 are superpicky, and you won't find any here. Yet, to 

 observe even a few crustaceans and amphibians in 

 Rocky Branch, at one time labeled the most 

 polluted urban stream in the state, is meaningful. 



Once a repository for all sorts of foul waste — 

 inks from the university's printing presses, oil from 

 the motor pool and milky discharges from the 

 cafeteria — Rocky Branch has been one of many 

 inland watercourses that ferry pollution toward the 

 coast. (East of campus, the creek joins with Walnut 

 Creek, which meets the Neuse River.) But even as 

 the university has cleaned up its act, reducing 

 current point source discharges to a handful, the 

 stormwater that pulses over a proliferating asphalt 

 landscape — tennis courts, parking lots, rooftops — 

 still contributes to the creek's demise. Like many 

 urban streams, the creek has been straightened, its 

 channel "armored" with concrete and riprap. The 

 energy that was once spread over slow meanders of 



the stream now has only one 

 place to go: down. Where the 

 flow of water is high, the 

 result is a deep, undercut 

 channel with steep, crum- 

 bling edges. 



Hardening or armoring a 

 stream channel with concrete 

 may get the water "out of the 

 way" but it exacts a price. 

 What provides relief for 

 upstream property owners 

 can mean big problems miles 

 below. Accelerated water 

 flow can transfer erosion 

 and flooding downstream. 

 And clean drinking water, 

 plenty of fish to catch and 

 quality areas for recreation 

 are directly linked to the 

 amount of development 

 and hard surfaces surround- 

 ing a waterway. 



This is the case along 

 Rocky Branch Creek, much of which is funneled through 

 culverts and cordoned by concrete walls. Other parts of the 

 creek flow swiftly through its steepening banks, undermin- 

 ing loads of mud and sediment. The final natural blow to a 

 degraded stream is the disappearance of habitat and the 

 community it supports. Nutrient-laden, silt-clogged waters 

 can no longer sustain animals. The disappearance of plants 

 along the stream also packs a wallop. Overhanging plants 

 shade and cool waters, making oxygen more abundant, 

 while their roots absorb pollutants and hold soil in place. 



It was along a relatively stable section of Rocky Branch 

 that the university decided to experiment with a new 

 technique known as bioengineering. This practice couples 

 plants with man-made structures to restore streams to a 

 more natural state. The combination serves two purposes. 

 The engineering principles help stabilize the bank and direct 

 the flow, while the biological principles improve wildlife 

 habitat, water quality and natural beauty of the stream. With 

 the help of a grant from the N.C. Division of Water Re- 

 sources and in conjunction with a N.C. Sea Grant work- 

 shop, a project was started along Rocky Branch last fall. 



The site was a natural choice. Bordered on one side by 

 a wide campus greenway, it allowed for a regrading of the 

 bank on one side to a more gradual slope. After excavating 

 and regrading, the repair team placed interlocking concrete 

 "A-jacks" at the toe, or base, of the slope. The empty spaces 



18 MARCH/APRIL 1996 



