HCFCD Vegetation Management Activities
The Harris County Flood Control District’s vegetation management program consists of the inspection and maintenance of more than 2,500 miles of open channels, 2,000 acres of stormwater detention basin property, and 2,350 individual buyout properties across Harris County. The vegetation management program can vary widely depending on variables such as access, slope condition, channel types, property rights, maintenance program goals and citizen requests for maintenance. In the Kingwood area, the Flood Control District’s maintenance activities mainly include mowing, selective clearing and desnag operations.
Mowing maintenance involves the cutting of grass, large weeds, invasive shrubs and trees to promote low-growing desirable grasses that provide erosion control benefits for earthen, engineered channels on property where the Flood Control District has a legal interest. Sites in the mowing maintenance program are typically maintained three times per year.
Mowing maintenance can be described by three categories that are typically determined by site characteristics:
- Mowing Category One – Channels within this category generally contain wide berms, subtle slopes, and easy access from roads or other channels. Large conventional cutting machinery may be used.
- Mowing Category Two – Channels within this category generally contain narrow berms, steep slopes, and may have little or no access on one or both sides from roads or other channels. Due to channel conditions, the use of large conventional mowing equipment is limited.
- Mowing Category Three – Channels within this category generally contain little or no berm, extremely steep or vertical slopes, and limited access from roads or other channels. Weed trimmers, machetes, or other small equipment are typically used to maintain this category.
Typically, sites designated for selective clearing are heavily forested with much longer intervals between maintenance than the mowing. Selective clearing sites are identified as natural channels where trees are allowed to grow on the channel banks and berms. Selective clearing operations remove non-native, invasive vegetation; healthy native vegetation is left in place, unless it:
- Hinders or interferes with access or inspection.
- Hinders flow or has the potential to hinder flow (usually by falling across the channel or growing in the channel bottom).
- May divert flow and cause toe-line failure or other erosion problems.
- Is located disadvantageously on the slope or in the channel bottom.
Desnag operations are assigned to channels where Flood Control District property rights are limited or nonexistent. Channels are normally desnagged on an as-needed schedule. This level of maintenance represents the lowest level of channel maintenance, mainly due to a lack of property rights, channel condition and/or limited access to the channel. These channels are typically otherwise unmaintained and heavily forested.
Desnagging involves the cutting of downed trees and removal of debris and other conveyance obstructions to allow the free flow of stormwater. Downed trees are cut into one- to two-foot lengths, left in place and allowed to float downstream. Work is limited to channel bed and banks only.