[furnished by David Swann 7/8/04]
Blunn Creek Walkabout
Woodward to East Live Oak
June 29, 2004
Participants: Adam Smith (a planner with City of Austin Neighborhood Planning and Zoning Development), Mike Lyday (a biologist with th City of Austin Watershed and Development Review), David Swann (South River City Citizens, or SRCC) and David Todd (SRCC) met at 8:30AM on Tuesday, June 29, 2004 at Big Stacy pool for the third and final Blunn Creek Walk, as part of the neighborhood planning process. We drove together to the southeast corner of the St. Edward's University property, where it is crossed by Blunn Creek, got out and walked north on the creek.
Flow: It was drizzling, as it has been on-and-off for the past three weeks (we've gotten more than 10 inches this month), and the creek was flowing well throughout the Woodward-East Live Oak reach that we looked at, growing increasingly strong and deep as we drew closer to East Live Oak. In many places the creek was four feet wide, and one to two feet deep. David Swann pointed out several flowing springs on the east slope leading to the creek in the Blunn Creek Preserve.
Topography: The terrain varies in this reach a great deal: from a 100-yard wide alluvial floodplain between Woodward and St. Edwards Drive, to a deep channel with 40-50 foot rocky bluffs within Blunn Creek Preserve. The breadth of the floodplain suggested that it might be difficult for St. Edward's University to expand its construction any closer to the creek.
Geology: Much of the creek bed is limestone, though it appears that there are sections in and near the Blunn Creek Preserve where there are lava flows along the bank, and under the creek bed.
Wetlands?: Mike Lyday was uncertain whether areas in this reach of the creek would be considered legal "wetlands" that would meet the soil, water and vegetative criteria. Most of the vegetation here was facultative, which could be dominant in either a upland or wetland area, so it would be necessary to look at the water regime and soils to see if these were formal wetlands. For instance, if one dug a foot-deep hole, and it filled with water within 4 hours, that might suggest wetland conditions. Also, if the soils were dark, mottled and/or had layers of peat or muck, they might be considered "hydric", and part of a wetland area.
Drainage: A number of drainage outlets feed directly to the creek, including flat sluiceways from parking on the east side of the creek, in the reach between St. Edwards and Woodward, and a 48-inch culvert which enters the creek on its west side, just north of Oltorf. It would be helpful if these drainage ways could be aligned with the creek's flow, and/or have energy dissipators, to reduce erosion.
Erosion: The most dramatic erosion sites were between St. Edward's and West Live Oak, including a 7' high by 60' long cut that had eroded the southwest bank by some 12' at Forest Creek Village. Forest Creek has approached the City about getting help stabilizing the bank, and the City has put this site on its list, but it is unlikely to get help soon, unless a built structure is threatened.
Erosion control (concrete and stone): Houses and apartment complexes along the creek's stretch between Oltorf and West Live Oak have installed some retaining rock and CMU walls that are four feet to seven feet tall, and in some cases, tiered in 2 separate walls. In many cases the walls abut the creek, or may be within 10 feet of the center-line of the creek. The City of Austin appears to have also installed a gabion across the creek only 100 feet south of East Live Oak, and we speculated that Sherwood Oaks neighbors might have installed a 3-4 foot high concrete dam for fishing, swimming, or possibly as a coffer dam (during installation of the storm sewer that passes under the middle of the creek).
Erosion control (vegetative): Some homeowners have planted nonnative vines such as virginia ivy or jasmine to hold the slope. The vegetation, if used with a gradual slope, seemed to create a more stable situation than the hardscape solutions. Mike Lyday suggested other tendrilled, but native vines to use for stabilization, including Virginia creeper, pepper vine or mustang grape, which might be used in conjunction with vines that have no tendrils but offer good color, such as coral honeysuckle.
Vegetation: The creek bottoms have a wide variety of vegetation, including canopy and understory trees such as cottonwoods, hackberries, bald cypress, tallows, pecans, cedar elm, live oak, spanish oak, juniper, dogwood, sumac, and willow. Within the uplands of the Blunn Creek Preserve there were still other types of plants, such as prickly pear, persimmon and agarita.
Invasive vegetation: Throughout the creek segment, there are invasive plants, including vibernum, bamboo, Chinese tallow, and nandina. Texas State University is currently conducting a study of invasive plants in Blunn Creek Preserve.
Fungi: There was a wide variety of fungi, ranging from mushrooms on the ground to leaf-like organisms on tree trunks.
Wildlife: We saw frogs, turtles, and a beehive during our walk.
Earthmoving: Roughly 5-7 years ago, bulldozers were in the creek bottomland on the west side of the creek, in the eastern portion of the St. Edward's campus, and did major clearing, evidently for laying storm drainage lines connected with construction of the University's housing.
Trash: Trash, including plastic bags, styrofoam cups, metal cans, as well as much heavier garbage, such as concrete picnic benches and steel wheel and car tires, was found along much of the creek, but especially in the segment between St. Edward's and Woodward. There was some discussion of whether there might be grates or booms along contributing storm drains, or cleanup programs along rights-of-way to prevent or reduce the litter.
Graffiti: Graffiti seemed limited to just two spots: the underside of the bridge at St. Edward's, and a wooden fence between Oltorf and West Live Oak.
Trails: There is interest in developing a trail that would enhance access to the Creek, as well as tie parklands in Stacy and Blunn Creek Preserve together. A well-developed trail system already exists in Blunn Creek Preserve. There is adequate space for a trail along the portion of the creek that passes through St. Edwards, though the area is flood-prone, and might be difficult to keep clear and protect from erosion of trail materials. In the area downstream of St. Edwards, at least outside of Blunn Creek Preserve, the creek passes between tightly developed single-family homes and apartment complexes, and would offer little space for a trail, though perhaps it would be possible to have trailheads or overlooks that would lead from nearby streets and follow the creek for only a limited way.
Data: Blunn Creek is monitored for water quality, vegetation, and recreational use on a three-year rotation by the City. The data are used to grade the streams on an Environmental Integrity Index, alongwith other major streams in a program that began with monitoring of Barton and Onion Creeks in the early 1990s. To augment this, there was discussion about exploring the Austin History Center archives for old images of the creek and its watershed, as well as looking through USGS or City of Austin records for streamflow information. There was also mention of how the Creek, and Blunn Creek Preserve in particular, would make a fine natural history research site for local schools.
End: The walkabout ended at 11:30AM.
Submitted by David Todd, 6/29/04