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Show Page 8 The Ogden Valley news Volume XXVII Issue IX September 15, 2020 DEPLETION cont. from page 1 tion lives at the highest category of risk from wildfire.) The project builds on work by Cal Fire (more formally known as the California Dept. of Forestry & Fire Protection), which in 2007 divided the state into “Fire Hazard Severity Zones” based on local topography, vegetation, weather, and fire history, among other criteria. The news organizations combined Cal Fire’s mapping with data from the 2010 U.S. Census. Putting the two together made it possible to figure out how much of the population, and how many communities, were at severe risk from wildfire. The analysis found 75 California towns and cities (with populations above 1,000) that were almost fully contained within “Very High Fire Hazard Severity Zones.” (More information can be found at www.directrelief.org/2019/07/ which-california-communities-are-most-vulnerable-to-wildfires/). What are the principle causes of increased fire risks in the West? Can any lessons be learned; thus, preventive measures implemented for the rest of the West? Groundwater depletion has now been linked to increased fire danger. According to an article in “Fluence,” there is a definite connection between groundwater depletion and increasingly destructive and frequent forest fires seen in the West, most clearly illustrated in the devastating fires seen in recent years in California. The article states, “In the West, riparian forests—forests adjacent to rivers and streams— depend on both surface water and groundwater for survival. Forests that rely entirely or in part on groundwater for survival are known as groundwater dependent ecosystems. “Inadequate monitoring and study of these ecosystems corresponds with a general lack of awareness that they and other nearby ecosystems are in trouble, especially during parching summers and droughts. “Groundwater-dependent ecosystems are resilient against water stress, but they begin to decline, sometimes irreversibly, if there is little groundwater available and when there’s also a shortage of surface water. This loss of habitat cascades into trouble for the structure and function of the ecosystem by interfering with reproduction, growth, recruitment, and mortality. For example, tree mortality has been on the increase in the Sierra Nevada region, with 66 million trees lost since 2011. In California, 66 million trees have been lost since 2015 alone. Tree loss on this scale has never before been recorded, and each dead tree provides more fuel for wildfires.” In addition to dying vegetation providing fuel for the rapidly rising number of massivelydestructive forest fires in the West, the depletion of water in groundwater aquifers kills the plant life that naturally cools ambient air and provides fresh oxygen. This reduction on an extremely large scale, of areas that were once plant- and tree-covered habitat, is alarming. It is this vegetation that cleans carbon dioxide, nitrogen dioxide, and particulate matter out of the atmosphere providing the clean fresh air that we once took for granted. In addition to the carbon dioxide and other pollutants that trees and plants capture, they also assist the soil’s natural ability to capture significant amounts of carbon. The propagation of asphalt and rooftops in vitally sensitive areas, especially in the high desert areas of Utah, such as Ogden Valley, is Shown above are the California communities most vulnerable to wildfires, with the darker red circles being the areas most vulnerable. The inset map (bottom left) shows the areas of California where water depletion of the aquifers is most extreme. It is interesting to see the correlation between high levels of water depletion and high fire danger. a bad idea in relation to the health and safety of a vital community and its population and the environment it and thousands of others rely upon, including those in the lower valley. Ogden Valley’s sensitive areas—the entire Valley being a prime watershed—provides the natural resources that sustains much of Weber County and its natural vegetation. This is where undisturbed aquifers, providing fresh water supplies, are regenerated, relying on open lands and healthy groundcover replete with natural vegetative cover that assists with the slow, steady percolation of precipitation into a healthy stock of groundwater. However, a steady deterioration of this watershed and its supporting eco-systems will only lead to the deterioration of the natural resources vital for stable, sustainable communities dependent on adequate supplies of highquality water, fresh air, and minimal fire danger from a green sustainable community supported by healthy, unthreatened water table levels. However, this delicate balance is being steadily challenged by encroaching development and recreational overload. Continued levels of high-density development on the hillsides, mountainsides and, even mountain tops of Ogden Valley will only continue to increase the depletion of our water tables and the accompanying water quality and supply, leading to the depletion of natural vegetation and a resulting rise is water contamination and destructive fires as we continue to dry out the valley and deplete its aquifers, much as California has done. Even within the short 50 years of living in Ogden Valley, I’ve personally witnessed a dramatic decrease in both seasonal and yearround water flows within the Valley’s rivers and streams at the foot of Wolf Creek canyon. I’ve also witnessed the drying up of many natural wetland areas and bogs, which are quickly being replaced by asphalt, cement and rooftops—water being dried up or detrimentally diverted or plowed over in favor of high-density development. The uncommon Utah cutthroat trout used to be rife in Eden’s streams and rivers fed by Wolf Creek, but are now rarely found—along with multitudes of other vanishing insects (water skeeters or water striders), a variety of frogs, and other animal life dependent on healthy and plentiful water systems. Many of the native cottonwood trees that lined the Valley’s riverbanks are dying out, along with other vegetation dependent on our once high water tables that are slowly receding. In a 2019 study by the Utah Dept. of Natural Resources (Special Study 165, Utah Geological Survey, a division of Utah DNR) titled “Characterization of the Groundwater System in Ogden Valley, Weber County, Utah, with Emphasis on Groundwater/Surface-Water Interaction & the Groundwater Budget,” states, “Future development of groundwater resources in any of the sub-basins (of Ogden Valley) would likely result in less discharge of groundwater to gaining sections of streams and reduced groundwater discharge to Pineview Reservoir. Shallow water in the valley-fill aquifer is generally recharged locally, likely focused along rivers, major creeks, and canals. Deeper valley-fill groundwater is recharged higher in the mountain block. Pumping groundwater from the mountain block (i.e., Powder Mountain) lowers the local water table, reducing the hydraulic gradient, and thus, recharge to the valley. Drawdown of the water table per unit volume pumped is more in bedrock aquifers than in the principal valley-fill aquifer due to substantially lower storage in bedrock aquifers. Mountain-block pumping will also likely affect mountain spring discharge and baseflow to mountain streams (Inkenbrandt and others, 2016). Increased pumping from the principal valley-fill aquifer will lower the potentiometric surface (an imaginary surface that defines the level to which water in a confined aquifer would rise were it completely pierced with wells), which will increase the seasonal capacity for recharge from losing streams and canals in the unconfined principal aquifer. Recharge from the unconfined principal aquifer to the shallow unconfined aquifer could decrease if the water table drops, and the composition of recharge to the confined principals aquifer will become more likely surface and precipitation sources. Hydrologic systems dominated by younger surface water and precipitation recharge are more susceptible to contamination…. “If water tables in the valley-fill aquifers decline significantly, either from increased pumping or decreased recharge from streamflow, canals, or mountain-block recharge (as on top of Powder Mountain) due to water resource development in the mountains and foothills, groundwater discharge to gaining sections of streams will decrease, which in turn will reduce streamflow to the reservoir (p. 97).” In its summary, the study adds, “Water use (in Ogden Valley) has increased slowly but steadily…. We hypothesize that development of water resources in any of the (Valley’s) subbasins would likely result in less discharge of groundwater to gaining sections of streams and reduced groundwater discharge to Pineveiw Reservoir. If the water table is lowered far enough by increased pumping in the bedrock or principal aquifers (located on top of the watershed and on the foothills), groundwater may not be able to flow to the shallow unconfined aquifer (on the Valley floor), and the principal confined aquifer would take all the flow from the unconfined principal aquifer, including water at the top of the water table that is degraded by septic-tank leachate. Because transmissivity and storage capacity of bedrock aquifers are lower, on average, than valley-fill aquifers, new supply wells in bedrock aquifers have the potential to negatively impact water levels in the mountain block, affecting mountain spring discharge and baseflow of mountain streams (Ibid).” The final paragraph of the study concludes, “While Ogden Valley is only sparsely inhabited, development pressures and water management choices have resulted in some degradation of water resources. Water in the valley is plentiful due to high precipitation and moderate evapotranspiration…. Water resource managers should be vigilant in protecting the quality of Ogden Valley’s groundwater resources as population and use grows (Ibid.)” |