District 6 has one of the lowest levels of impervious cover of all the districts and one of the highest levels of protected open space, including over 5,000 acres of the Balcones Canyonlands Preserve system.
Approximately half of the district drains to the drinking water supply reservoirs of Lake Travis and Lake Austin. In addition, 70 percent of the district lies over the recharge zone of the Northern Edwards Aquifer. Springs discharging from the aquifer provide critical habitat for the threatened Jollyville Plateau Salamander.
The upper portion of the Lake Creek watershed is identified as a high priority problem for water quality. Nutrient concentrations in this watershed are chronically elevated. Potential sources of nutrients include leaking wastewater infrastructure, permitted discharge and land application of treated wastewater effluent, and excessive use of fertilizers.
The lack of storm drain infrastructure (curb and gutter) within some of the older subdivisions in the Walnut Creek watershed contributes to localized flooding of buildings, streets, and yards. Major clusters of drainage complaints are shown in blue on the map below.
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The Watershed Protection Department addresses drainage and environmental problems using a three-tiered approach of capital improvement projects, programs, and regulations. Examples of these strategies in District 6 include:
Capital Improvement Projects: Watershed Protection has completed the construction of a regional stormwater pond in the Walnut Creek watershed, a culvert upgrade in the Rattan Creek watershed, and channel modifications in partnership with Williamson County to improve flood conveyance in Lake Creek. Projects are also planned for the next five years to upgrade a creek crossing and install storm drains to resolve flooding issues in the Walnut Creek watershed as well as to restore native aquatic vegetation along Lake Austin.
Programs: The management of Hydrilla in Lake Austin is an important program in this district. This aggressive, invasive plant has posed significant public safety threats as its dense growth impacts flood flows, water intakes, and recreation on the lake. The Hydrilla is controlled through the use of sterile grass carp and periodic winter drawdowns. Another key program is Salamander Protection which provides monitoring and impact assessments of salamander species to promote recovery of salamanders while also allowing the continued recreational use of Austin’s unique natural resources.
Regulations: With the first watershed protection ordinances in this area adopted in the late 1970s, regulations have been a key strategy for this district for over 35 years. Since the majority of the existing development occurred with these regulations in place, less than seven percent of the protected creek buffers are encroached by impervious cover. Keeping development safely back from waterways reduces the need for future capital projects. In addition, staff recently revised the code to implement recommendations of the Lake Austin Task Force related to docks, bulkheads, trams, and a zoning overlay.