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Cienega Creek Hydrologic Research and Findings

The Pima County Regional Flood Control District has provided support over the years for PAG's monitoring program, in recognition that this unique perennial stream, with its pristine native riparian habitat, is a critical resource in southern Arizona.

Portions of both Cienega Creek and its tributary, Davidson Canyon, are protected through their designation as Outstanding Arizona Waters by the State. PAG Watershed Planning research reports contributed to this designation including reports on water quality, geology and source flows.

PAG's 20 years of hydrologic monitoring along Cienega Creek indicates that the region is in the midst of a long-term drought. A developing headcut, and erosion feature PAG began studying in 2002, surprised many who recognized the major successes of restoration, since the Pima County Natural Preserve was established in Lower Cienega Creek in 1986.

Annual Report
The most recent technical reports for the Cienega Creek Monitoring Project are shown below. This report summaries PAG's groundwater and surface water monitoring between July and June each fiscal/monitoring year. The report contains monitoring methodology, comprehensive maps, and graphs of trends for surface flow volume, wet-dry flow lengths, groundwater levels and water chemistry. It also contains information on drought, erosion and repeat photography.

  • PAG Cienega Creek Annual Report 10-11: Notable findings for the 2010-2011 monitoring year include:
    • Continued decrease in mean annual stream flow
    • Lower groundwater table at most wells, but less drastically than in 09-10
    • Lowest flow length (1.26 miles) on record
  • PAG Cienega Creek Annual Report 09-10: The 2009-2010 monitoring year was remarkable for having the lowest September water levels on record.
     

ADWR Water Protection Fund Award for Headcut Study
Interest in preserving Cienega Creek continues to drive monitoring, discussion and community engagement. In recent years, a large erosion feature (a headcut) developed, radically changing the stream habitat as it migrates upstream. Since 2002, the headcut has migrated over 1,200 feet and has grown to 12 feet deep and 20 feet wide. PAG has collected baseline data on structural habitat, vegetative cover and hydrologic conditions to evaluate the changes over a two-year period. The resulting report discusses the findings on the changes of the water table slope, the increase in fish habitat diversity, loss of vegetation cover and change in vegetation composition. Many new discussions have resulted from recent field trips, presentations and meetings regarding needs for restoration, potential causes, and possible impacts on other aspects of habitat. PAG is participating in a Sky Island/Sonoran Desert Restoration Network which formed to share information and to engage scientists, land managers, citizen volunteers and landowners throughout the region.

Drought Findings

Cienega Creek experienced record breaking drought conditions in summer 2013.  PAG conducts flow mapping in June in Davidson Canyon and Cienega Creek Outstanding Arizona Waters to determine the minimal length of flow in the during the driest part of the year, coordinated with other river mapping efforts across the region.  The perennial flow extent was found to be a record low of 0.93 miles in June 2013.  This is 25% lower over one year. The June 2013 flow is  10% of the flow extent compared to the wet years in the mid 1980s when fully 9.5 miles flowed in Preserve during the dry season.  PAG’s hydrologic monitoring at Cienega Creek reveals that drought impacts have been noticeable since 2002. Although the creek saw some recovery in 2006-2008, the drought has since become more severe. Each June since 2011, the record low flow miles are recorded.  Current groundwater levels also remain significantly below pre-drought levels.

Drought Planning:

PAG’s 2012 investigation of shallow groundwater areas revealed private wells tapping into this riparian area and other similar areas.  Drought conditions can be highly localized in the desert southwest so rural private well owners and the riparian habitat live in may experience unique conditions and risks as temperatures rise and precipitation become more variable in coming years.

Since  drought information is primarily disseminated by large municipal water providers in urban areas, PAG works with the Local Drought Impact Group to recommend that special consideration for drought stage triggers and outreach be given to vulnerable areas including riparian, shallow groundwater and areas with rural households dependent on private wells. We are approaching a critical threshold for creek in the pre-monsoon season, so we support a focused alert message to areas in localized areas.

PAG contributes hydrologic monitoring data through the AZ Drought Watch, in order to help the Governor’s Drought Task Force assess the status of drought statewide. Thanks to Pima County support, PAG’s data is highly valued by this effort because of the consistent long-term data set that has been collected along Cienega Creek. Because Cienega Creek has been monitored for many years and has relatively low urban development, these findings provide insight into how drought affects our natural environment.

 

KVOA - NASA images capture Tucson - then and now - July 26, 2012

 

Record Low Creek Levels: NASA aerial imagery how lush the Santa Cruz River was when it flowed before major city growth. Rare remaining riparian areas in the county continue to be vulnerable to reduced water levels.  KVOA interviews PAG's senior watershed planner to find out how current drought is impacting Cienega Creek. July 26, 2012, to see the full story visit http://www.kvoa.com/news/nasa-images-capture-tucson-then-and-now/

Take a virtual field trip to the headcut.

Davidson Canyon

The extent of streamflow in Upper Davidson Canyon has declined substantially since 2003. Since the channel and pools completely dried out during the summer of 2005, PAG has not seen native fish there. Lowland leopard frogs are still present along the reach. This reach of the creek is currently under stress from off-road vehicle and cattle use, but the county has made efforts to exclude these activities from the riparian area.

Highlights of PAG Studies on Cienega Creek

The PAG Watershed Planning library has additional publications on Cienega Creek from outside sources.

 

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