Map corrected Jan. 22 at 9:54 a.m. The original map incorrectly showed US 183 continuing north from where it should have intersected with Toll 183A. The map has been updated.
Sharon Krienke has lived in Cedar Park since 1971, before the city was incorporated. With the north fork of Brushy Creek and Spanish Oak Creek coming through her family’s property, she said they have witnessed a fair share of flooding over the years.
“We’re used to it,” Krienke said. “We had times we couldn’t go across the bridge on Brushy Creek for sometimes weeks because the water would stay across it.”
Though flooding in Central Texas is nothing new, federal and local entities are addressing the issue in new ways in 2019. The Federal Emergency Management Agency is revising flood plain maps that determine whether homeowners must purchase flood insurance. In Cedar Park, a voter-approved stormwater program is making headway.
The FEMA updates are the result of a seven-year collaborative effort in Williamson County to update the area’s flood insurance rate map. The new map, which FEMA is expecting to finalize in the fall, will affect hundreds of Williamson County residents as properties receive or lose flood-risk designations.
The new map is based on a recent watershed study by the Upper Brushy Creek Water Control and Improvement District, the operator of flood-control structures in the Upper Brushy Creek Watershed.
Insurance companies use FEMA’s flood insurance rate maps to determine if flood insurance is legally mandated for a property. Congress mandates that federally regulated or insured lenders require flood insurance on mortgaged properties that are in high-risk flooding areas. Even if properties are not located in these areas, mortgage lenders may still require flood insurance, according to FEMA’s website.
Michael Lafferty, a certified flood plain manager with the city of Leander, said he does not know how many properties in Leander will move into or out of the flood plain in the new maps. In early 2018, cities had a chance to submit appeals based on the preliminary map. Lafferty said the city submitted appeals regarding a few subdivisions and is still waiting to hear back from FEMA to see if those subdivisions will be in the flood plain in the new map.
“In general, I would say the flood plain has gotten larger,” Lafferty said. “But as far as individual property, depending on where you are in the city, it could be a very small change, almost insignificant. There are some areas where there are significant boundary increases, but it’s kind of on a case-by-case [basis].”
The new map shows structures moving into and out of the flood plain in Cedar Park, according to Darwin Marchell, the director of engineering for the city of Cedar Park. Marchell said in an email there are 352 structures in a current FEMA flood plain zone and 384 structures in the proposed map.
Data for the Upper Brushy Creek Watershed Study was compiled by Williamson County and multiple municipalities, including Leander and Cedar Park. The new maps were developed using updated development information, detailed topographical data and modern technology, providing an extensive update the area has not seen in nearly three decades.
Leander City Engineer Wayne Watts said the area’s flood insurance rate map was last updated in 2008 and was based on work that was done in 1991. Both Leander and Cedar Park have seen significant growth since then.
Watts said the Upper Brushy Creek Watershed Study was based on a 2012 snapshot of Leander.
“Lots of things have happened in Leander since 2012, like during that [time], doubling the population,” Watts said.
Watts said once the map is finalized, city staff plans on sending more updates to FEMA based on newer data.
‘Flash flood alley’
Central Texas is nicknamed “Flash Flood Alley,” according to KVUE chief meteorologist Albert Ramon. Ramon said flooding occurs here because of the area’s proximity to the Gulf of Mexico and the nature of the area’s topography.
“It really only takes an isolated thunderstorm that sits over an area for a short period of time, mainly west of the interstate, to cause some issues,” Ramon said.
Ramon said moving west of I-35, the amount of soil decreases, and limestone is not far below the surface.
“So if you think of the soil as a sponge, it doesn’t take a whole lot of rainfall for you to get saturated soil and then in turn cause runoff to low-water crossings,” Ramon said.
Low-water crossings are roads that intersect either a low area or a creek, Ramon said. He said while Austin experiences urban and street flooding due to the amount of concrete it has, issues in Cedar Park and Leander typically stem from low-water crossings.
Ramon said the past winter and fall have seen above-average rainfall, and the rest of winter and spring will likely be wetter than average due to that rainfall.
“Soil is going to stay saturated; lakes are up,” Ramon said. “Several inches of rainfall in the wrong place can cause some big-time issues.”
Cedar Park stormwater drainage program
One of the most notable steps Cedar Park is taking to address flooding is creating a new stormwater drainage program. Voters approved a proposition in May allowing for the redirection of a portion of sales tax revenue to fund the program. The program handles infrastructure projects; provides maintenance of drainage infrastructures, such as creeks, ponds and ditches; and handles permits.
The stormwater program is now in the process of prioritizing 19 critical drainage projects, such as areas of Block House Creek, Riviera Springs and Deer Run. These 19 problem areas were discovered after the city hired a consulting firm to identify problem areas in 2016. Emily Truman, the stormwater program manager, gave an update on the program at a Dec. 13 City Council meeting.
“We are now working on prioritizing these projects with an updated criteria that focuses on the protection of property and structures as well as public safety,” Truman said at the meeting.
Truman said the ranking of these projects should go before City Council for comment and approval in early 2019. The ranking will then serve as a guide for implementing the projects.
Marchell said flooding mainly occurs in older areas that were developed before Cedar Park was incorporated and therefore were not designed to city drainage standards. He said most of the drainage projects the city will be focusing on address flooding in these places.
Watts said the city of Leander does not have flooding-related projects in the works at this time, and the city has not seen a need to create its own stormwater program.
“I’m not expecting to do so because of our topography,” Watts said.
As a longtime Cedar Park resident, Krienke said she is in favor of the steps Cedar Park is taking to improve drainage through its new program.
“I think all towns ought to implement things like that,” Krienke said. “Work on it before it happens. It saves the taxpayers and the landowners a lot of problems.”
Reporting contributed by Iain Oldman.