Managing Bull Creek Watershed
by Bob Oertel
|"That's it," many thought when the Bull Creek Watershed Protection and Flood Prevention project at Columbus, Georgia was completed in the mid-1960's. "Our flooding problems are over. Lets relax and enjoy the lakes and parks."
True, the sometimes wild and rambunctious Bull Creek had been effectively shackled. A combination of soil and water conservation measures on the land, channel improvements and 11 earthen water-retarding structures had been installed. Working together, they would keep rainwater under control from the time it fell on the 45,000 acre watershed until the now-harnessed Bull Creek emptied into the Chattahoochee River just below downtown Columbus, Georgia.
The most severe test for the completed project came in July 1994 when Hurricane Alberto dumped 27 inches of water over western Georgia. After the deluge, Johnny Johnson, then chief of the Rainwater Division, City of Columbus, said, "We didn't have any major flood problems, due in large part to the watershed project and our maintenance system. The watershed measures worked as scheduled."
With that statement, Johnson had put his finger on one of the most important keys to successful watershed programs: total watershed management and comprehensive maintenance of installed measures. The Columbus "M&M" experience is widely regarded as one of the best in the country.
First of Its Kind
The Bull Creek project is unique in that it was the first project of its kind approved (June 29, 1961) under the Watershed Protection and Flood Prevention Program (TP 83-566). Up until that time, both agricultural and urban land were directly involved.
About 2/3 of the watershed area was rural, mostly in the upper reaches, while the lower 1/3 was urban. The goal was flood prevention on 1,416 acres of land and for 1,000 residences on the eastern and southern sides of the city of Columbus. Almost all of the landowners in the rural area were cooperating with the Pine Mountain Soil & Water Conservation District (SWCD) and had developed conservation plans with the help of Soil Conservation Service (SCS) personnel. Half of the planned conservation treatment had already been applied to the land. However, about 50 miles of roadsides still needed erosion control measures.
Four thousand acres of the Fort Benning Military Reservation extended into the eastern edge of the watershed. All this land was being properly managed under agreements with the Pine Mountain SWCD.
Managing and Maintenance Go Together
"Putting in the dams and the other conservation practices was only the beginning," says Bob Lahl, Chief, Rainwater Management, Department of Public Service, Columbus Consolidated Government. "Looking after these works of improvement, being sure that they function the way they are supposed to and don't deteriorate, is all a part of our maintenance program. In addition, we must manage all the land within the watershed and cope with the many ever-changing problems associated with a rapidly urbanizing area."
Gone now are almost all of the more than 200 farms that 30 years ago covered the land in the upper reaches of the watershed. Instead, the land that once soaked up most of the rainfall has become essentially "waterproofed". New houses, commercial buildings, shopping malls, streets and highways cover the once absorbent earth and instead now "shed" practically all of the rainfall. "Every new building, street and road means we have just that much more runoff water to manage," says Bob. "And the way development is happening so fast, our management and maintenance work becomes even more essential and complicated."
Realizing the growing importance of management of the entire watershed area, Dick McKee, now Public Services Director, several years ago reorganized Service responsibilities. The Rainwater Division, with Bob Lahl, Manager, is responsible for earthen dams and spillways, ditches, sewers and stormwater. The Parks and Recreation Division is responsible for the water within the lakes and the public parks around the lakes. The expected deposition of sediment in the upper ends of the watershed lakes was recognized when the SCS engineers designed the structures in the early 1960's.
"They included enough capacity to store sediment that might occur in the next 50 years," explains Lewis Fokes, Natural Resources Conservation Service (NRCS). "The extreme rapid change from rural to urban that is going on now could hardly have been fully anticipated 35 years ago. Some sub-watersheds have changed so fast that they are now totally urban with 100 percent runoff. All this extra runoff makes the maintenance work by the city of Columbus so much more critical. To their well-earned credit, the City is doing an excellent job," says Lewis.
Attention to Dams
"We want people to enjoy the lakes and surrounding areas," says Bob. "They are welcome to walk on the dams. But, we do not want them to drive on them with motorcycles, ATV's or pickups because these machines tear up the grass and cause erosion." To correct such past abuses and head off future trouble, the Rainwater Division has built and now maintains fences around all dams. Narrow entrances allow walkers free access to the dams.
The tops of dams are especially treated so that mowers and maintenance vehicles can move across them without causing damage. A mixture of topsoil and #5 gravel is spread over the top to make a more protective base. This area is then seeded to a mixture of vigorously growing grasses, making the top attractive as well as capable of handling any maintenance vehicles. The grass cover over the entire dam is fertilized annually. "Even though the fertilizer bill is quite substantial, it is well worth the cost because we can maintain a healthy and solid stand of grass to protect the dam," Bob says.
All dams are mowed each fall. This not only makes them more attractive, but also stops pesky shrubs or tree seedlings from becoming established. "As you might expect, not everybody agrees with us when we mow because they are afraid we might cut down some wildflowers or what they consider attractive weeds or grasses," says Bob. "It's just not possible to time the cuttings to satisfy everyone."
On any future dams of any size, Bob recommends a 3:1 slope. Mowing can then be done with power mowers instead of being done by hand labor, as is now the case with the slopes of their detention ponds.
An unusual soil sliding problem developed on the Cooper Creek Dam in the summer of 1998 after a protracted dry period that was followed by a heavy 4 inch rain. Heavy cracking developed on the dam face during the dry weather. When the rain finally arrived, these cracks suffered substantial erosion. NRCS Engineers feel the severe "shrink-swell" problem traces back to a higher than expected colloidal clay content of fill material used during the dam construction. Even though this is not considered a major problem, portions of the fill will be removed and replaced with material having a lower colloidal clay content.
Sediment buildup in several lakes has been substantial because upstream construction tears up land and removes its protective cover. Dredging has been done at the upper end of one lake. Because of the heavy expense, any future dredging that might become necessary in other lakes will be spread out over several years. Spirited opposition to dredging arises among some local residents, largely because they do not want their lake 'drained down' to remove the sediment. On the other hand, lakeside owners prefer clear open water instead of having their lake be choked with sediment and looking like a weedy swamp.
Sediment Basins Help
Columbus has its own Erosion and Sediment Control Ordinance, even though there is also a state-wide ordinance. Along with the requirements of erosion and sediment control plans to guide construction, sediment basins (sometimes called 'small detention ponds') are a must. "Even though these are relatively small in size," explains Bob, "they help take part of the burden off the watershed dams."
Developers must maintain these small ponds during construction and clean the sediment out of them once the work is completed. When this is done, and the areas around the ponds are grassed, the ponds are deeded over to the city and become the responsibility of the Rainwater Division to maintain. Thus far, 28 have already been transferred, with 40 more soon to be added to the city's responsibility.
Bob sees the need for larger, regional-type detention ponds as a way to provide greater flood control to help out the watershed lakes. "Not only that," he says, "but it would be more efficient for us to look after these fewer and larger ponds than a much larger group of little ones scattered all over the city."
Citizens and Stormwater
After every rain event, there is what could be called a stormwater/citizen interface, according to Bob. "We have all the physical pieces in place to handle stormwater, but this is where our citizens can either help us or make our job harder. Too many times when there are problems, we find that the reason is because somebody has either intentionally or unintentionally done something stupid." Bob tells of an irate citizen calling to complain, "Our yard is getting flooded just because your sewer won't drain off the water." Checking out the problem, Bob and his men found that a case of empty beer bottles had largely plugged the inlet. In another case, an inlet was stopped up with grass, weeds, pine needles and trash that had been thrown in the street by an unthinking homeowner.
The city has taken several steps to educate the public about what they can do to help the stormwater system continue to operate efficiently. Among these are prominently marking each one of the city's 13,274 stormwater inlets so that people will recognize them. There is a city-wide 'NO DUMPING' policy forbidding dumping. A series of public service announcements are regularly broadcast to urge individuals and businesses to dispose of their 'throwaways' in the proper manner. "Believe me", says Bob, "soil, excess fertilizer, pesticides and sprays of all kinds washing off yards, grease and oil and a whole lot of other things wash along our streets and into the sewers. These so-called 'non-point source' pollutants are largely a people-caused problem. We are trying to tell people to be more careful."
As Lewis and I walk along the edge of tree lined watershed lake #28 and Heath Park, I suddenly realize that here is actually the Bull Creek project in microcosm. Unaware that anyone else is nearby, a lone lady (well up in years) wearing a sun bonnet to shade her face, sits on a chair close by the water's edge. Never taking her eyes off the bobbing cork of her fishing line, she tells me simply, "I come here most every day. It's fittin, to take it all in and be by myself. That's important you know." Then she quickly adds, "Course, I ketch my share of fish, too."
Looking past the lady, we see an elderly couple, hand in hand, walking along the shore, pausing now and then to look out across the lake's quiet water. A young man jogs along the path at the base of the dam. Across the water, a maintenance crew tidies up around some trees alongside the lake. Attractive homes, hidden along the tree-lined shore, are safe from any danger of flooding. There is the dam itself, holding back runoff from two square miles of land, storing 22 acres of permanent water and with enough capacity to temporarily detain 70 acres of flood water.
I recall how, more than 30 years ago, I stood at this same spot and watched earthmoving machines pile up enough dirt to make this 32 foot high dam. I also remember how several years later, at this same location, I watched Heath Cooper Rigdon, widow of John Rigdon (the real sparkplug for this watershed project) being honored with a park in her name for their pioneering efforts.
The Bull Creek Watershed Project was the crowning conservation achievement for 'Big John', County Commissioner and supervisor of the Pine Mountain SWCD, and 'Red' Avera, the Columbus SCS conservationist. More than any other individuals, they conceived it, and over the years pushed it to completion. Even though both are now deceased, Columbus remembers them with gratitude. With one of the best M&M programs anywhere, this city is making sure Bull Creek will never flood again. Big John and Red would be proud of it all!
For more information, contact: Bob Lahl, Rainwater Division, 1152 Cusseta Rd., Columbus, GA 31901 (706)653-4159, fax (706)576-4537 or Lewis Fokes, NRCS, 212 Baker St., Buena Vista, GA 31803 (912)649-3131, fax (912)649-2393.
©2000, 1999, 1998 Land and Water, Inc.