This morning Madison, Wisconsin awoke to yet another day without rain, and there are no good chances for rain in the seven-day forecast. Much of southern Wisconsin remains in a moderate to severe drought, so says the National Weather Service on its drought information page. According to the National Weather Service (NWS) the precipitation deficit in Madison, WI for the year as of September 3, 2012 is 8.03″. So even if a freak storm blows through in the next week and dumps two to three inches on us, the area will be feeling the impacts of this drought for some time.
The drought will impact land and water resources (see Drought Synopsis) and although much of the current concern is rightfully with impacts on the Wisconsin’s agricultural industry the state’s rural and urban forests are also at risk.
Even though the extreme heat of July and August has eased, the drought has not and, in time, we may begin to lose mature trees and shrubs–maybe not this year but eventually. Certainly by next growing season you will see the cumulative stress of drought and insects take a toll on some of your favored trees and shrubs. This prospect poses a dilemma for those of us concerned about trees in the public urban landscape as well as those on our own property: should we water or not? My general advice is to water valued specimen trees as much as possible to keep them alive because of the benefits trees provide to the urban landscape in terms of shading, cooling, CO2 capture, and oxygen release.
If you are watering trees and shrubs, keep it up. If not, and you decide to get started, just forget the lawn for now. But for the rest of the season and until the ground freezes–usually around Thanksgiving–put an inch of water or 30 gallons per week on each tree and shrub that you want to see leaf out again next spring. In times of drought where will this extra water come from? Well, I offer some conservation suggestions Recommendations below.
Impacts of the drought on the Lake and on Groundwater
This is a hard question to answer and depends upon a number of variables such as soil type, timing, intensity and duration of precipitation, vegetation and land use changes. Groundwater hydrologists are still trying to develop good methods of measuring or modeling groundwater recharge. Maribeth Kniffen (2011) provides a good introduction to the complexities of groundwater issues in her report: groundwater status report.
It is known (FOLW, 2009, “Lake Wingra: a vision for the future.”) that Lake Wingra receives about 34% of its water supply from storm water runoff. Another 35% comes from springs and other ground water sources. The last 31% comes from direct precipitation (rain, snow, sleet, and hail.) So, presumably the drought has had some impact on the amount of water (or lake level) in Lake Wingra. ground water levels.
A better measure of the impacts of this drought on groundwater is probably long-term trends in depth to groundwater. The depth to ground water varies across the landscape and thus is measured at a large number of permanent well points scattered across the state and nation. The United States Geologic Survey (USGS) maintains a national network of groundwater monitoring well. The information from these wells is available online at the USGS Groundwater Watch, Climate Response Network The two monitoring wells nearest Madison are in Richland Center and Whitewater on this map. The Richland Center well depth to ground water was 12.47 feet on September 1, 2012. The Whitewater well read 6.95 feet on August 21, 2012, again less than 10% below normal. (See the charts here for explanation of the numbers.)
Dane County has its own groundwater well network. The data from a well near Mazomanie is available here The depth to ground water in the Mazominie well has dropped from 10 feet on May 19 to 12.43 feet on September 3, 2012.
Recommendations for Groundwater Conservation
Conserving water is a wise practice anytime but is especially critical in times of drought. There are practical things that every homeowner can do to help.
Minimize the amount of rainfall that flows from your property into the street (where it flows into the storm sewer and on to the lake) and thus maximize the amount that soaks into the ground.
- Direct downspouts into the lawn or garden.
- Create a rain garden.
- Use rain barrels to capture rain fall.
- Install a permeable driveway.
- Minimize impermeable surfaces on your property.
- Save “grey water” from the sink and bathtub and use it to water plants.
- Don’t wash your car.
- Let cooking water cool before pouring it on the garden.
Municipalities and public agencies can also conserve water if they tried a few of these initiatives:
- Identify areas in the watershed that could serve as large groundwater recharge areas. The marshes around Lake Wingra, for example or the Arbor Hills Greenway.
- Install permeable surfaces on public property throughout the watershed.
- Incorporate green infrastructure into every new storm water management project.
- Retrofit old storm water facilities with green infrastructure (bio-swales, rain gardens, infiltration basins, etc.)
- Incorporate infiltration and other green infrastructure into each road, street, or highway reconstruction.
- Install rain gardens in street medians (Midvale Boulevard, for example.)
Of course, one can’t save nonexistent rainfall during a drought, but we need to start now to carry out these steps to be ready to save every drop possible when the rains return.