Fighting invasive species
In rural Kearny County, Kan., water from the Arkansas River is a crucial resource for irrigating crops and sustaining ranch animals. So when an invasive plant takes root on the riverbanks and begins sucking up more than its fair share of water, county leaders take action.
“Kearny County is totally agricultural land,” says Shannon McCormick, county commissioner. “We try not to deplete the groundwater, and if we could use it to grow crops instead of a plant using it with no benefit, it would be advantageous to all the taxpayers.”
Last fall, county officials began studying the spread of tamarisk, a non-native shrub that is growing along waterways throughout the southwestern United States. Also known as salt cedar, the bushy plants can grow eight feet to 12 feet high and consume about twice the amount of water as native plants.
Besides stealing water, the plants impede wildlife access to water sources and deposit thick layers of dry brush that create a plentiful fuel source for fire. “We had started hearing about other people controlling it,” McCormick says. “There’s a pretty big effort in Colorado, and there has been a big effort in New Mexico to control it. So we just took it from their lead and decided to start studying it.”
In September 2004, the county contracted with Colorado Springs, Colo.-based Native Communities Development Corp. (NCDC) to obtain high-resolution satellite imagery and create geographic information system (GIS) maps of the plants’ locations along 32 miles of the Arkansas River within the county. NCDC created a detailed inventory of tamarisk in Kearny County using QuickBird satellite imagery from Longmont, Colo.-based DigitalGlobe, Feature Analyst software from Missoula, Mont.-based Visual Learning Systems and proprietary algorithms. The data was delivered as ESRI shapefiles ready to be integrated in the county’s new GIS and formatted for use by precision pesticide applicators’ onboard navigation systems.
In one week, county officials had the satellite images (which show details on the ground as small as two feet across) and GIS maps of the invasive shrubs, native plants, trees and crops. The images and maps revealed about 875 acres of mature tamarisk, which are estimated to consume about 682 million gallons of water annually. County officials estimate that the same amount of water could be used to irrigate $495,000 worth of corn. “If we could equate how much water a tamarisk used versus how much corn used, then it means something to people,” McCormick says. “If you just talk about tamarisk itself, it really doesn’t equate to anything.”
For $25,000, the county received maps and satellite imagery it could submit to the state Agriculture Department and use to supplement applications for state and federal grants to help fight the plant’s growth. County officials also can use the maps to show landowners where the plants are growing on their property as a first step to eradication. “Our main mission was to develop the study and let all the people from the state and federal levels look at it,” McCormick says. “We’re just kind of waiting for them, hoping we’ll get either federal or state aid in controlling the tamarisk.”