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Drought status
Given the low precipitation and minimal snow over the last few years, there continue to be many questions about our water supplies. The following is offered to help explain the current situation and factors that could impact what actions may or may not be necessary looking forward.
News involving the current drought began with the Medford weather station recording the lowest precipitation on record in 2013. Have Medford Water Commission’s records reflected similarly low precipitation levels?
Precipitation records kept by Medford Water Commission (MWC) reflect moisture received at our Big Butte Springs water source, which tend to be about 50% higher than what is recorded in Medford. However, precipitation levels tend to go up and down similarly, whether in town or at the springs.
In the western states, dry summers through September result in water supplies being highly dependent on precipitation received the previous fall and winter, particularly snowmelt. Therefore, like most western water suppliers, MWC keeps precipitation records based on a water year that runs from October to September, not a calendar year.
The water year that ran from October of 2013 through September 2014 included the very dry fall of 2013, so that water year started off very low, and despite some wetter months after that point, at the close of the 2013-14 water year, total precipitation at the Big Butte Springs was only 85% of normal.
We have now just completed another water year running from October 2014 through September 2015. Precipitation this year has actually been close to normal, with total precipitation at Big Butte Springs being about 93% of average at the end of August. However, with very little of this precipitation falling in the form of snow, local snowpacks were at historically low levels, and in turn the lack of snowmelt has resulted in many local streams running much lower than normal since early in the summer. The lengthy period of very hot weather in late June through early July also worsened already-dry conditions.
Medford Water Commission has been less impacted by drought and lack of snow than some other water providers. Why is that?
There are a number of factors that determine how much a water supplier is impacted by different weather conditions. A primary component in short term droughts is how reliant the supplier is on moisture received in a single year. To some extent this relates to how much carry over storage from prior years is available. The Big Butte Springs are fed from precipitation received on Mt. McLoughlin. Some of this, particularly snowmelt from high on the mountain, may not reach the springs during the same water year. Though the springs do show declines, they are not as impacted by a single year’s precipitation as many other water supplies. As a result, our water supplies were not as impacted by last year’s low precipitation levels as some local water providers.
This water year, the bigger factor was not how much overall precipitation was received, but how little of the precipitation came in the form of snow. Since snow provides more lasting recharge of streams and aquifers than rain, it plays a big role in summer water supplies for water providers in the western US due to lack of rain during the summer months. While we too see some impacts from less snow, Mt. McLoughlin is unusually porous, and whether received as rain or snow, nearly all precipitation received goes into the ground, rather than much of it running off, as occurs in most watersheds. Consequently, the Big Butte Springs are less impacted than most water supplies if precipitation comes in the form of rain, instead of snow.
In our case, Willow Lake water levels can also play a role. Although MWC does not directly use water from this lake, due to our sharing water rights to the Big Butte Springs with the Eagle Point Irrigation District (EPID), Willow Lake water is used to supplement EPID’s water needs. This enables MWC to more fully use the springs water. While Willow Lake typically refills each winter, there have been a few years when the lake was drawn down more than normal during the summer and the following winter was unusually dry, resulting in the lake not refilling that year. When that occurred, less water from the springs was available for MWC’s use the following summer, and the operations of both MWC and EPID were impacted.
Due to slightly more than average drawdown during the hot summer of 2014, normal precipitation levels were needed over the winter to refill Willow Lake. Fortunately, ample precipitation was received this winter, though most of it came in the form of rain. The lake therefore filled by early February 2015, but without any snowmelt, inflows this summer were less than normal. As a result, from the end of April until the first of July, MWC reduced its normal Big Butte Springs usage from 26 million gallons of water per day (mgd) to 20 mgd. This was done to enable EPID’s water needs to be met without use of Willow Lake storage until later in the summer. Management of Willow Lake always involves EPID and MWC working together, but was particularly important this year. Those actions were quite effective, although Willow Lake levels will be well below average heading into the winter.
The Rogue River water source also contributes significantly to MWC’s ability to meet demands, particularly in years where water supplies are strained. As treatment and pumping associated with this supply is considerably more expensive than the springs, it is used only as much as necessary to meet water demands from spring through fall. However, this source is a particularly valuable resource when less water from the springs is available. It is in fact what enabled us to meet water demands during May and June, despite reducing our use of the Big Butte Springs.
In normal water years, the Rogue source is used less during the spring and fall, but provides about half of our water during peak summer months. However, the Robert A. Duff treatment plant on the river has the capacity to treat up to about 70% of our peak demands, and still be well under what our Rogue River water rights allow. We are also fortunate to benefit from the fact that Lost Creek Dam provides storage of water that can be released to sustain Rogue River flows during the summer months. While the Rogue River flow levels are still reduced during years with low precipitation or lack of snow, they are not subject to the extremes that would be experienced without this storage. Our withdrawals also represent a very small percentage of total Rogue River flows. Therefore, when less water from the springs may be available, the shortfall can typically be made up from the Rogue source.
Treatment capacity of the Duff plant currently poses a more significant potential limitation to our use of Rogue River water than availability of river water. In June, the Duff plant operated at close to its current peak capacity during the particularly hot weather that occurred while we were still bringing less springs water to town than usual. Although this would not be the case in a normal year when full capacity from the Big Butte Springs is available all summer long, if conditions similar to this June continued to occur over the next few years, some curtailment actions could become necessary. While expansion of the treatment plant is underway, it will be five years before full capacity will be completed.
Does Medford Water Commission have any plans to restrict the water usage of its customers when water shortages occur?
Although stream flows were lower than normal the last two summers, we were able to meet our customers’ water needs without restrictions being necessary. As always, however, we encouraged all water users to review and implement the many water use tips offered in newsletters and the conservation section of our website, as well as to take advantage of services we offer such as our Lawn Watering Infoline at 541-774-2460, free sprinkler system evaluations, and toilet rebates.
Water use restrictions are always a possibility if water supply conditions or facility malfunctions result in such actions being necessary and appropriate. We have a Curtailment Plan in place, which defines actions if our ability to fully supply our customers’ demands is constrained. While drought is the most common cause of such measures being implemented, this plan also recognizes that drought is not the only reason why a water utility might find itself unable to meet full demands. The Curtailment Plan includes a series of five thresholds or stages, with actions becoming increasingly stringent based on the level of water shortage. For example, actions range from customer awareness and suggestions for voluntary measures in Stage 1 to very severe restrictions in Stage 5.
Regardless of whether or not curtailment actions become necessary, MWC will continue to remind and encourage its customers to use water wisely. Even in years of plenty, water is a precious resource, the waste of which is inappropriate and unnecessary.
Updates on drought conditions can be accessed on these websites:
US Drought Monitor
USGS WaterWatch
US Water Monitor
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