The Goal: To restore year-long creek flow supported by stable groundwater levels. During years of drought, to maintain groundwater levels within 3 feet of the channel bed.
Reviving our desert waterways requires hard science to understand the dynamics at work in the watershed and chart a course for increasing surface flows. We are creating a flow budget for the Upper Tanque Verde Streamshed that analyzes inflow and outflow against a reserve groundwater level, which needs to remain stable to support flow in the creek.
To support creek flow we are identifying and promoting opportunities with landowners to install water-harvesting and stream restoration features along Upper Tanque Verde creek to reduce outdoor use of potable groundwater, improve soil health to prevent erosion, and increase infiltration to recharge the shallow groundwater that supports the creek.
The Upper Tanque Verde shallow groundwater system supporting discontinuous annual creek flow and riparian trees has stabilized in the last 10 years. Groundwater levels respond rapidly to changes in pumping and recharging streamflow events. The responsiveness of this shallow aquifer will require careful management through both dry seasons (March through June and September to November) and drier years. Groupings of cottonwood and ash trees, once prevelant in pockets along the banks, have mostly disappeared due to heavier historic pumping of groundwater. The mesquite bosque has remained stable on the flood terraces. The channel and floodplain access has remained fairly intact with only significant downcutting along select reaches.
Streamshed Priority Actions
Download Action Map here: October 2016 (pdf file)
- Reduce groundwater demands along the creek to help stabilize, restore, and maintain groundwater levels within 1-3 feet of the channel bed surface during dry periods.
- Promote stormwater infiltration throughout tributary drainages and floodplains to buffer groundwater levels during drier seasons and drought years in this critical area.
- Remove invasive, non-native plants along the creek corridor including Giant reed (Arundo donax).
Annual Flow Budget
Reviving our desert waterways requires hard science to understand the dynamics at work in the watershed and chart a course for increasing surface flows. We’ve created a flow budget that analyzes recharge compared to groundwater demands. A positive balance is required to recover and stabilize groundwater levels to support flow in the creek.
Developed by Catlow Shipek, with input from various partners, the Upper Tanque Verde Streamshed Flow Budget is in balance most years in recent history. 2015 was an exception due to greater storm flow providing more recharge to the groundwater. However, the aquifer has limited storage capacity due to underlying bedrock and can be quickly depleted by groundwater pumping in drier years. To stabilize groundwater levels to support a healthy riparian habitat even during dry years we recommend a reduction in groundwater pumping by ~10% (80 acre-feet) especially during the warm, dry season of March to July and an enhancement in stormwater infiltration by ~10% (880 acre-feet). Then groundwater levels during dry years can remain stable and during wet years can support flow in the creek nearly year-round. WMG continues to work with Tanque Verde area partners and residents to regularly update and distribute a collective stewardship plan to reach this goal.
Streamshed Area: 18 sq.miles
Shallow Groundwater Area: 9 sq.miles
Upper Tanque Verde Creek Channel Length: 7 miles
Current Status: Intermittant-dry (surface flow < 50% of the year); seasonal groundwater fluctuations > 10ft
Flow Target: Intermittant-wet (surface flow 60% to 95% of the year)
Groundwater Target: Stabilize water level depths to be within 3ft of channel bed throughout year