| Title |
Investigators | Department | Objectives | Approach Keywords | Progress Reports | Impact Statements | Publications | |
Project * COL00727 | |
| Title | Effects of Irrigated Agriculture and Riparian Vegetation on Fish Habitats in the Arikaree River Basin of Colorado |
| Investigator(s) | Oad, R; |
| Department | Civil and Environmental Engineering |
| Objectives | The overall goal of this interdisciplinary research is to find a balance in maintaining the agricultural economy and a healthy riparian habitat for fish and wildlife in the Arikaree River Basin. This goal is in sync with USDA goal no. 4 and CSU AES goal no. 6 in that a better understanding of water use by irrigated agriculture and riparian vegetation will allow decision makers to evaluate options for future agricultural and environmental management. Yuma County surrounds much of the Arikaree River and is one of the richest agricultural regions in Colorado. In addition to the local economy, the health of the riparian habitat must be maintained to support the continued survival of threatened fish species. Aspects of the health of the riparian system include both water quantity and water quality. Continued analysis of the available water and how its quality is affected by irrigation will help to insure the continuation of the unique habitat of the Arikaree River. The interdisciplinary research team has defined the following specific objectives: i. Establish the hydrologic linkages between irrigation pumping, the groundwater response, stream levels, and habitat characteristics in the Arikaree River on which fish survival and reproduction depend. ii. Quantify brassy minnow habitat conditions and constraints needed for survival and reproduction. iii. Cooperate with farmers and water managers in the Arikaree River basin, as well as state agencies, to develop scenarios that predict the future of the Arikaree River and critical fish habitat under anticipated scenarios such as extended drought conditions, climate change, changing cropping patterns, declining well efficiencies and continuing declines in the water table of the regional High Plain Aquifer . The proposed research project will particularly provide information related to the irrigated agriculture in the river valley, which will be conjunctively analyzed with information on groundwater behavior and the resulting river stream and fish habitat. Some of the tasks associated with the agricultural component of the larger research project are as follows. a. Continue to document what crops are currently grown and the amount and pattern of water use in the valley. Use the groundwater models to further understand the groundwater hydrology as it is affected by irrigation water use and its influence on the stream flow. b. Working with local water users and water management organizations such as the Groundwater District, research options for various cropping patterns to reduce crop water requirements. c. Conduct further analysis using the White method or a modified form of the White method resulting from this research to estimate the riparian vegetation water use. d. Use remote sensing evapotranspiration models such as ReSET and developed groundwater models to compare and validate the estimate provided by the White method |
| Approach | The research approach recognizes that opportunities to address the water needs of irrigators and the stream flow requirements are many and diverse. These might include development of a program to retire irrigation pumping water rights, water exchanges, and stream augmentation programs. To successfully conduct such preservation and restoration programs, it is imperative that the watershed community and stakeholders recognize the need to protect and preserve the river, collectively decide on which options they are willing to endorse and buy in to any programs that are set forth. The Colorado Department of Wildlife (CDOW) and Agricultural Experiment Station (AES) are funding ongoing research by Drs. Fausch, Durnford and Oad, which includes the river reach running through the Fox Ranch. The goals of these projects are to gather and analyze scientific data related to irrigation pumping, its effect on the groundwater, and the fish and wildlife in the Arikaree river basin. The research will explore scenarios that will include extended drought conditions, changing cropping patterns, declining well efficiencies and continuing declines in the regional High Plain Aquifer water tables. This information will provide fish managers, irrigators and water managers the information needed to make informed decisions leading to the conservation of native fish populations in working landscapes, while protecting the agriculturally-based economy of the region. Most importantly, methodologies will be developed that will be useful in other areas throughout the arid west where irrigated agriculture and critical fish habitat are hydraulically connected and water is a constraint on the robustness of both systems. Research regarding riparian vegetation water use is also relatively new and methods used to estimate riparian water use are still being tested. A modified form of the White method and remote sensing ET models may be two methods for measuring riparian evapo-transpiration that may result from this research. In the future ,the project needs to increase collaborative work with the local water users for researching options for crops and the associated water use. We will need to add a public outreach component and promote interaction between the researchers and the local stakeholders. |
| Keywords | Irrigation, Crop water use, Groundwater pumping, River ecology, Fish and wildlife, Fish habitat |
| Progress Reports | |
| 2004 | The Arikaree River, on the eastern plains of Colorado, provides unique habitat, recreation and cultural sites, and agricultural benefits. In recent years, long sections of the river have dried up during summer and fall months. This prevents it from providing a suitable habitat for fish and wildlife that depend on the river during hot summer months and reduces recreation opportunities along the river. Adjacent landowners and community members, interested in preserving the Great Plains way-of-life, are concerned that continued seasonal drying will permanently affect water uses and habitat in the river basin. Previous work done addressing this problem includes several theses written by Colorado State University students in prior years. A thesis by Fardal (2003) examined the effects of groundwater pumping in the basin on stream continuity, and a thesis by Griffin (2004) examined the possibility that groundwater dewatering was the sole cause of the problem. A thesis by Scheurer (2002) described in-stream habitat conditions of the river. Funding for this project was approved in June 2004. A Masters-level graduate student began field work at that time. The primary focus is to access the impact of irrigation pumping on the groundwater levels, which in turn affect the river stream flow. Stream flows are also influenced by evapo-transpriation from the riparian vegetation. To monitor stream flow and groundwater levels , river stage gages and groundwater monitoring wells were installed. There are 28 wells between 2 and 5 meters deep, and 6 stage gages located along one reach of the river. Half of the wells are in an area of high riparian vegetation density, half in a low density area. This will allow a comparison of groundwater responses to varying vegetation effects. Pressure sensors have been installed in some wells to continuously monitor water levels. Water levels will be correlated with external influences such as riparian vegetation evapo-transpiration (ET), irrigation pumping, and climatic conditions. Preliminary results from monitoring wells, stage data, and farming data suggest connections with all three, and especially with riparian ET. Significant diurnal fluctuations in the water level demonstrate the impact of riparian vegetation. With the easing of drought compared with previous years, river drying was not as severe. With the coincident loss of leaves and cessation of irrigation pumping for the season, water levels in the river began to rise significantly, as expected. |
| 2005 | The Arikaree River, on the eastern plains of Colorado, provides unique habitat, recreation and cultural sites, and agricultural benefits. In recent years, long sections of the river have dried up during summer and fall months. This prevents it from providing a suitable habitat for fish and wildlife that depend on the river during hot summer months and reduces recreation opportunities along the river. Adjacent landowners and community members, interested in preserving the Great Plains way-of-life, are concerned that continued seasonal drying will permanently affect water uses and habitat in the river basin. Funding for this project was approved in June 2004, and a M.S level graduate student began field work at that time. The primary focus was to assess the impact of irrigation pumping on the groundwater levels, which in turn affect the river stream flow. Stream flows are also influenced by evapotranspriation from the riparian vegetation. To monitor stream flow and groundwater levels, river stage gages and groundwater monitoring wells were installed during the summer of 2005. There are 28 wells between 2 and 5 meters deep, and 6 stage gages located along one reach of the river. Half of the wells are in an area of high riparian vegetation density, half in a low density area. This has allowed a comparison of groundwater responses to varying vegetation effects. Pressure sensors have been installed in some wells to continuously monitor water levels. The data collected during 2005 summer were analyzed to estimate the volume and timing of riparian evapotranspiration and irrigation pumping. The seasonal ET rate for a zone of High Cottonwood Density was 1349 mm/yr (4.43 ft/yr). Throughout the basin, this corresponds to a total volume of 12.3 million m3 (9940 ac-ft) of water lost to riparian ET. Irrigation application rates varied considerably from year to year due to efficient management practices. They totaled 682 mm (2.24 ft) in 2004 and 469 mm (1.54 ft) in 2005, for a total volume of 83.7 million m3 (67,876 ac-ft) and 57.6 million m3 (46,673 ac-ft) respectively. The timing suggests that irrigation alone was not responsible for observed declines in surface flow in the Arikaree River and drops in the water table in the associated alluvial aquifer. The results suggest that irrigation pumping was driving long-term regional declines in the HPA water level. Riparian vegetation lowers water levels in the zone most sensitive to water table declines, and, later in the season, at a time when alluvial aquifer recharge is already reduced by irrigation pumping. In the future, riparian ET of the cottonwood areas will be measured using remote sensing technology that combines regional satellite data with localized ET measurements to calculate regional ET. REEM (Regional ET Estimation Model) is a process that uses the energy balance at the top of the canopy to estimate ET. This model is being used to calculate regional riparian vegetation ET along the Middle Rio Grande. |
| 2006 | The Arikaree River, on the eastern plains of Colorado, provides unique habitat and agricultural benefits. In recent years, long sections of the river have dried up during summer and fall months. This prevents it from providing a suitable habitat for fish and wildlife that depend on the river during hot summer months. Adjacent landowners and community members, interested in preserving the Great Plains way-of-life, are concerned that continued seasonal drying, in conjunction with groundwater pumping, will permanently affect water uses and habitat in the river basin. Funding for this project was approved in June 2004, and a M.S . level graduate student began field work at that time. The primary focus was to assess the impact of irrigation pumping on groundwater levels, which in turn affect the river and stream flow. Stream flows are also influenced by evapo-transpiration from the riparian vegetation. To monitor stream flow and groundwater levels, river stage gages and groundwater monitoring wells were installed during the summers of 2004 and 2005. There are 28 wells between 2 and 5 meters deep, and 6 stage gages located along one reach of the river. Half of the wells are in an area of high riparian vegetation density, half in an area of low density. This has allowed a comparison of groundwater responses to varying vegetation effects. Ten pressure transducers were installed in the summer of 2005 to continuously monitor water levels. Nine more pressure transducers were added in the summer of 2006. The data collected during 2005 were analyzed to estimate the volume and timing of riparian evapo-transpiration and irrigation pumping. The seasonal ET rate for a zone of High Cottonwood Density was 1349 mm/yr (4.43 ft/yr). Throughout the basin, this corresponded to a total volume of 12.3 million m3 (9940 ac-ft) of water lost to riparian ET. Irrigation application rates varied considerably from year to year due to efficient management practices. They totaled 682 mm (2.24 ft) in 2004 and 469 mm (1.54 ft) in 2005, for a total volume of 83.7 million m3 (67,876 ac-ft) and 57.6 million m3 (46,673 ac-ft) respectively. The timing suggests that irrigation alone was not responsible for observed declines in surface flow in the Arikaree River and drops in the water table in the associated alluvial aquifer. The results suggest that irrigation pumping was driving long-term regional declines in the HPA water level, while riparian evapotranspiration significantly affected the water levels in the alluvium in the short-term. Riparian vegetation lowers water levels in the zone most sensitive to water table declines, and later in the season, at a time when alluvial aquifer recharge is already reduced by irrigation pumping. Further monitoring was continued in the summer of 2006 in order to compare results from the 2005 and 2006 growing season. In addition, Landsat 4 TM satellite images were collected and are being used with ERDAS (a CSU ET-measurement model) to measure the riparian ET for the 2006 growing season. This ET estimate will be compared with those from previous years and will be used to more accurately model the groundwater fluctuations in the basin. |
| Impact | |
| 2004 | Results of this study will equip local irrigators, landowners, and natural resource managers to protect the interests of the community to provide water for multiple uses in the most beneficial way. The scarcity of water, especially of surface water, on the Great Plains requires careful stewardship to maintain economic and aesthetic benefits. |
| 2005 | The research project in its first year had positive impacts. We have been very successful in working with the local community including farmers, Groundwater Conservation District and the Nature Conservancy. The Nature Conservancy especially has been very supportive of the study and provided us access to their Fox Ranch on the river. All the data collection activities are conducted on the Fox Ranch property. The project results are being used by the mentioned groups to identify options for reducing irrigation pumping towards the goal of better river ecology. The research team has submitted three proposals, of which one by Dr. Kurt Fausch as principal investigator has been approved for funding by the Colorado Department of Wildlife. The funding is supporting a Ph.D student in the Department of Fisheries at CSU. We have also submitted research proposals to USDA/NRI in year 2005 and now for year 2006. |
| 2006 | Continued improvements in evapotranspiration estimates and additional records of groundwater pumping will allow for a more accurate groundwater model of the Arikaree River basin. The local community, including farmers, the Groundwater Conservation District, and the Nature Conservancy's Fox Ranch, is invested in finding a balance in maintaining the agricultural economy and a healthy riparian habitat. Data provided by further groundwater monitoring, satellite imagery analysis and surveyed information from farmers will help to develop a plan for the agricultural and wildlife communities to survive together in a sustainable manor. After a lawsuit filed by the State of Kansas against the States of Nebraska and Colorado, farmers close to the river alluvium were encouraged to retire their wells. While this was appropriate for some, many farmers wish to continue cultivating their land and keeping their business running for generations to come. It is our hope that this research will help to provide a solution for protecting the riparian habitat that is at risk while preserving the local agricultural economy. |
| Publications | |
| 2005 |
Fardal, Lisa (2002): M.S Thesis, Department of Civil Engineering. Griffin, Steven (2004): M.S Thesis. Department of Civil Engineering. Griffin, Steven (2005): Paper presented at the Hydrology Days, Colorado State University. Wachob, Erik (2005): M.S Thesis. Department of Civil Engineering. |
| 2006 |
Riley, Linda 2006.: Poster presented at the Hydrology Days, Colorado State University. |