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USFS Looks to the Future in Upcoming Forests to Faucets Analysis AS THE W O R LD 'S URBAN FOOTPRINT EXPANDS AND THE CLIMATE CHANGES, THE US DEPARTMENT OF AGRICULTURE FOREST SERVICE W IL L UPDATE ITS 2 0 1 1 STUDY TO CLARIFY THE CONNECTION BETWEEN WATERSHED HEALTH AN D DRINKING WATER SUPPLIES. he connection between forests and water quality and streamflow has been recognized for ages. More than 2,000 years ago, Plato observed that cutting mountain forests dried up the springs and floods carried the soil to the sea, "leaving the land nothing but skin and bone" (de la Cretaz & Barten 2007). This is somewhat self-evident--urban areas and farmland are used more intensively and there fore discharge more soil and pollutants--but a wealth of research also strongly supports the fact that trees and forests improve water by filtering runoff, recharging groundwater, and regulating the timing and magnitude of streamflows (Holmes et al. 2018, Binder et al. 2017, de la Cretaz & Barten 2007, Brown & Binkley 1994). Forests are the original water treatment facility (see the sidebar starting on page 43), and they naturally provide myriad benefits (e.g., clean air, recreational enjoyment, wildlife habitat). Land-use decisions related to water will become more important as the earth becomes more populated. In the United States, populations continue to grow, which means a larger urban footprint and more water needed for agricultural, industrial, and household uses in the country. So as pressure for clean water increases, land conversion and climate change also apply pressure on the resource (Sun et al. 2008). As the US Department of Agriculture Forest Service (USFS) and partners embark on an update to the 2011 Forests to Faucets analysis, the aim is to promote better understanding of the connection between Layout imagery courtesy c i Sally Clagg; CLAGGETT & MORGAN | JULY 2018 * 110: 7 | JOURNAL AWWA 41 Sierra Club v. EPA 18cv3472 NDCA Tier 5 ED 002061 00160092-00001 natural landscapes, water quality, and water availability with an eye to the future. FOREST FRAGMENTATION Forests have a unique and signifi cant role in the water cycle (Figure 1). Day after day, evaporation moves water from oceans and land up to the sky. When this water precipitates back to land, it can recharge groundwater or run off into streams, but the majority returns to the atmosphere through plant vapotranspiration in the unending hydrological cycle (Pimentel et al. 2004). Forests tran spire more water because of their large biomass and deep roots. Per haps most important, mountainous regions--which are primarily for ested--receive a disproportionate amount of precipitation. More than 50% of the water supply in the United States originates on forest lands; this increases to 65% in the West (Furniss et al. 2010). Forests cover roughly one-third of the conterminous United States (a.k.a. the Lower 48). By 2060, forests are projected to shrink by 16 million to 34 million acres because of urbaniza tion (USDA 2012). Most forests in the United States (-56% ) are pri vately owned (Butler et al. 2010). These predominantly family-owned forests (i.e., not owned by a corpora tion) consist of smaller tracts (50 acres or less), and there is increasing pressure to fragment these lands into even smaller parcels. Fragmentation of forests will continue to compro mise their ability to function (USDA 2012). Privately owned forests pro vide the vast majority of water sup plied to population centers in the South and Northeast (USDA 2014). Across the West, insect epidemics, drought, and a loss of markets have put forests at higher risk for wild fires. Exacerbating these issues, fuel has been building up in most parts of the country--an unintended result of decades of fire suppression-- making fires larger and more severe, which can destroy water quality. The American Forest Foundation released a report in 2015 that showed at least one-third of forests in key drinking water watersheds are at high risk of wildfire and are pri vately owned. Private landowners may want to manage their land to protect against fire or other threats, but 77% of landowners cited the high cost of management as a barrier (American Forest Foundation 2015). Without resources for the landowner, public benefits from private forests will continue to erode. Upland forests are not the only land use beneficial to water quality; natural areas (e.g., grasslands, chap arral, sagebrush) are also important. Riparian areas and wetlands provide critical filtering of water pollutants coming off of farms, ranches, and developed areas. INCREASING THREATS USFS's new analysis will focus on surface-water supplies, which are the source of most (about 77%) drink ing water in the United States (USEPA 2008). Surface water (e.g., streams, ponds, reservoirs) is natu rally affected by topography, land use, soil, and other physical features; FIGUR E 1 An illustration showing the importance of topography in the water cycle Source: NASA Because mountainous regions are mostly forested, more than 50% of the water supply in the United States originates on forest lands. 42 CLAGGETT & MORGAN | JULY 2018 * 110: 7 | JOURNAL AWWA Sierra Club v. EPA 18cv3472 NDCA Tier 5 ED 002061 00160092-00002 compared with groundwater, it is more easily contaminated by patho gens and pollutants because of its accessibility. In addition, surface waters face challenges such as harm ful algal blooms that typically do not affect groundwater quality. Threats to surface-water quality are often exacerbated by human activity and warmer water temperatures. Threats on Tap, a recent report by the N atural Resources Defense Council, details widespread concern that the Safe Drinking Water Act is not keeping up with enforcement of emerging, widespread contam i nants, including some, such as harmful algal blooms, that are increasing because of climate change (Fedinick et al. 2017). Upstream forests that provide source water protection should enable cost savings for downstream water utilities by reducing treat ment requirem ents. In a recent study, W arziniack et al. (2017) found that, on average, water treat ment plants with lower sediment and lower total organic carbon in their source water have lower treat ment costs, supporting earlier work by Ernst (2004) on the importance of source water protection for water utilities. In addition, betterquality water in the influent may reduce the formation potential of disinfection byproducts and their associated risks to public health, as well as reduce waste streams and other operational burdens. Threats to forests include con version to other land uses, wildfire, invasive pests, and other climateinduced stresses such as increased temperatures and inconsistencies in water availability as mentioned previously. Climate change can alter a forest's ability to regulate water flows (Bergkamp et al. 2003), exacerbating the issue of water stress. Another exacerbating issue is forest fragmentation, which is ac c e le ra tin g in m ost region s (Furniss et al. 2010). These com pounding threats to forests make future modeling vital. WATER STRESS Communities exert a large, con sistent demand for w ater-- a resource that may be seasonal and weather-dependent--and most have felt the stress of water short ages. Water stress is likely to worsen with the now -fam iliar double whammy of population growth and climate change. It can be evaluated by looking at water supply and water demand at the w atershed level. U S F S's new national Forests to Faucets analy sis uses a simple model--the Water Supply Stress Index (WaSSI)--to simulate water supply stress across the United States. The water sup ply stre ss for a w atersh ed is defined as the ratio of water Forests reduce the flow and runoff energy th at can cause scouring to streams and stream banks. Photo courtesy o f Sally Claggett How Forests Clean Water Trees are nature's w ater filtration systems; they purify the w ater that even tually flows through our faucets. Naturally vegetated and forested areas reduce adverse impacts on w ater quality from impervious areas and agricul ture, keeping watersheds cleaner. Water cycling through forests can be simplified into two distinct paths, both of w hich improve water quality. The "downw ard" path starts with pre cipitation; vapotranspiration powers the "upward" path. The strong pump ing action fueled by photosynthesis draws water up to the tree canopy, where it is transpired. But not all the water drawn up by the trees is released through vapotranspiration; some travels back down through the phloem-- distributing carbohydrates made during photosynthesis-- and out through trees' roots, influencing the surrounding soil. PHYSICAL PROCESSES Treetops intercept rain and snow, which trickle down stems and trunks to the forest floor. At this point, the forest-water interaction already has begun to reduce continued p. 44 CLAGGETT & MORGAN | JULY 2018 * 110: 7 | JOURNAL AWWA 43 Sierra Club v. EPA 18cv3472 NDCA Tier 5 ED 002061 00160092-00003 demand to water supply: WaSSI = D /S, where D is water demand (i.e., the total water withdrawal from different water users as defined by the US G eological Survey [USGS], which conducts a water use survey every five years), and S is water supply (i.e., The purpose of this project is to quantify, rank, and illustrate the direct geographic connection between forests, surface drinking water supplies, and populations that depend on them. How Forests Clean Water (amtmed) runoff. The humus layer on the forest floor acts like a sponge. From the tree canopy to the topsoil, up to 18 in. of precipitation can be absorbed. The mature forest soil layers-- including their abundant carbon-- physically hold water between the soil particles, which allows further infiltration and adsorption by roots. Unlike other types of land cover, forests have little surface erosion, and therefore less sediment is transported to surface water. Forests also reduce the flo w and runoff energy that can cause scouring to streams and stream banks-- a common source of sediment in developed areas. BIOCHEMICAL PROCESSES Forest soil hosts microbes that interact w ith pollutants, changing their chemistry and improving water quality. An example of the yeoman's work these microbes can accomplish in healthy forest soils is denitrification, in w hich excess nitrogen compounds such as nitrate are converted and released as inorganic nitrogen gas, the most common compound in the atmosphere. Water is absorbed by roots into the woody structure of the tree through osmosis. This movement is supercharged by evapotranspiration, which exerts a pull strong enough to get w ater and nutrients 200 vertical feet or more up into the crown of the tallest trees. Forests use external nutrients (i.e.,from soil, atmospheric deposition, or dissolved in storm runoff) for growth and cellular processing. A tree's trunk is full of porous tissue called xylem, which acts as a system of straws that run up and down the tree. Sap or water molecules can travel through this tissue, but it forms a barrier that filters larger molecules. Xylem thus removes bacteria and contaminants such as excess nutrients (e.g,, nitrates and phosphates), metals, pesticides, chem ical solvents, oils, and hydrocarbons. Fast-growing trees, such as cottonwood, are deliberately used to clean contaminated groundwaterthrough the natural phytoremediation process. Certain chemicals are broken down, degraded, and lost to the atmosphere through transpiration and volatilization. Nonforest vegetation also transpires, but the biomass and longevity of trees makes their transpiration more substantial in cycling water and nutrients. the streamflow at each watershed plus the groundwater withdrawal from USGS). USFS's modeling system tracks water supply monthly for all 2,100 larger sub-watersheds (Hydrologic Unit Code 8) in the United States. Climate change and precipitation variability are the major drivers of water supply. Factors that affect water demand include population growth, crop irrigation water use, socioeconomic change, and associ ated energy demand. The nexus of land use/forests, populations, and water supply is of primary interest as the USFS undertakes its next national Forests to Faucets analysis (see the sidebar on page 45). SCOPE OF STUDY The national Forests to Faucets version 2.0 (referred to as F2F2) will build upon the original Forests to Faucets analysis (Weidener & Todd 2011) by updating that study's base data layers for the continental United States and by forecasting new threats. The F2F2 analysis, which is still in the production phase, aims to promote better understanding of the connection between watershed health and drinking water supplies. F2F2 will take a closer look at current and projected hydrologic systems and water stress. The analysis will be based on a series of biophysical and demographic data layers using the 12-digit Hydrologic Unit Code (F1UC12) watershed as its base unit. The United States is divided and subdivided into successively smaller hydrologic units that are classified into four levels: regions, sub-regions, accounting units, and cataloging units (USGS 2018). The hydrologic units are arranged or nested within each other from the largest geographic area (regions) to the smallest geographic area (cataloging units). Each hydrologic unit is identified by a unique HUC consisting of two to eight digits based on the four levels of 44 CLAGGETT & MORGAN | JULY 2018 * 110: 7 | JOURNAL AWWA Sierra Club v. EPA 18cv3472 NDCA Tier 5 ED 002061 00160092-00004 classification in the hydrologic unit system. There are more than 88,000 HUC 12s watersheds in the continental United States, and their average size is roughly 35 mi2. Analysis at this scale provides information useful for states, counties, water utilities, and large land-management units such as national forests, while allowing for standardized comparisons in differ ent areas. The HUC 12 scale is useful for evaluating risk factors since the spatial importance of these risks is often lost when summarized at larger scales. Also, this scale helps water shed managers target problem areas, which is an improvement over a shotgun approach. The F2F2 analysis can be thought of in three parts. The first part will be an analysis of an HUC12 water shed's inherent ability to produce clean water based largely on land use. In the Forests, Water and People analysis (Barnes et al. 2009), this was called "Ability to Produce Clean Water" and was not specific to drinking water. However, most watersheds that have a stake in drinking water protection also sup port a high proportion of at-risk aquatic biodiversity, providing opportunities for joint benefits from water quality protection (USDA2012). The second part of the F2F2 anal ysis will look at which HUC12 watersheds are the most important to surface drinking water users. To determine these watersheds, flow is modeled upstream of source water intakes to indicate how that water has been influenced by upstream watersheds. The " importance fac tor" is directly tied to the approxi mate number of people who depend on that water source for their drink ing water. The third aspect will allow the user to weigh various threats to the quality and quantity of surface drinking water. They include threats to forests (e.g., forest loss or damage from fire or pathogens) and threats to water supply (i.e., using the WaSSI Sample Questions the National Forests to Faucets 2.0 Analysis Will Address Which sub-watersheds have an inherent ability to produce clean water based on their land-use characteristics? Conversely, which watersheds are likely candidates for watershed restoration to provide higher-quality water? What is the relative importance of each sub-watershed in my state for providing drinking w ater to downstream consumers? How many US surface drinking w ater consumers/water supply utilities depend on public forest lands for water supply? How many depend on unprotected private forest land? Which w ater supply watersheds are likely to be most affected by development/land-use change throughout the United States over the next 20-plus years? What threats other than development (e.g., wildfire, invasive pests, water yield change because of climate change) do w ater supply watersheds face, and to what extent are they likely to be a concern? tool). Climate change is considered in both threat categories. Threats will also be forecast for two future time steps (i.e., 2040 and 2090) when data are available. Results of the F2F2 analysis are intended to help planners, land man agers, water resource managers, and anyone concerned with water sup plies make critical land-use deci sions. The end goal is to have a dynamic and interactive Internet presence to convey the various out comes of the F2F2 analysis depend ing on users' needs. Current and future (projected) land-use statistics will be generated for each HUC 12. The data produced by this assess ment could also be used to identify opportunities for market-based approaches to sustain clean water production. On the whole, the F2F2 project will provide a broad view of landuse characteristics and water supply threats to watersheds that feed surface drinking water sources. It does not displace the need for local land-use data, local knowledge, or different analyses of hydrologic regimes. However, F2F2 will be useful for long-range plan ning, municipal education, and pri oritization of regional water needs, including indicating where alterna tive water supplies may be needed. It w ill help land m anagem ent decision-makers know where prac tices may affect water needs, either positively or negatively. ABOUTTHEAUTHORS Sally Claggett (to whom correspon mm dence may be addressed) is program coordinator I for the US Forest Service, 410 Severn Ave., Ste. 209, Annapolis, MD 21403 USA; sclaggett@fs.fed.us. (Readers can contact her with any feedback on this project, including whether this analysis will be valuable for utilities and any potential applications or pitfalls.) She has 16 years of experience working in watershed forestry as a USFS liaison to the Chesapeake Bay Program. Claggett earned a master o f science degree from the University of Oregon, Eugene, CLAGGETT & MORGAN | JULY 2018 * 110: 7 | JOURNAL AWWA 45 Sierra Club v. EPA 18cv3472 NDCA Tier 5 ED 002061 00160092-00005 Ore., and a bachelor of arts degree from the University o f Colorado, B oulder, Colo. Robert Morgan is an ecological engineer in Springdale, Ark., who retired from the Beaver Water District. https://doi.org/10.1002/awwa.1114 REFERENCES American Forest Foundation 2015. Western Water Threatened by Wildfire: It's Not Just a Public Lands Issue, www.forestfoundation.org/ stuff/contentmgr/files/1/3d9Sbbe 1b03a0bdf4c726534d438b0ab/misc/ final,,fire,,re port pdf (accessed November 2017). Threats to forests include conversion to other land uses, wildfire, invasive pests, and other climate-induced stresses. Trees and forests improve w ater by filtering runoff, recharging groundwater, and regulating the timing and magnitude of streamfiows. Photo courtesy o f Sally Claggett 46 CLAGGETT & MORGAN | JULY 2018 * 110: 7 | JOURNAL AWWA Sierra Club v. EPA 18cv3472 NDCA Tier 5 Barnes, M.C.; Todd, A.H.; Lilja, R.W.; & Barten, P.K., 2009. Forests, Water and People: Drinking Water Supply and Forest Lands in the Northeast and Midwest United States. US Department of Agriculture Forest Service, Newtown Square, Pa. www.fs.usda.gov/naspf/publications/ forests-water-and-people-drinkingwater-supply-and-forest-landsnortheast-and-midwest (accessed November 2017). Bergkamp, G.; Orlando, B.; & Burton, 1,2003. Change: Adaptation of Water Resources Management to Climate Change. World Conservation Union (IUCN), Gland, Switzerland. Binder, S.; Haight, R.G.; Polasky, S.; Warziniack, I ; Mockrin, M.H.; Deal, R.L.; & Arthaud, G., 2017. Assessment and Valuation o f Forest Ecosystem Services: State o f the Science Review. General Technical Report NRS-170. USDA Forest Service, Northern Research Station, Newtown Square, Pa. Brown, T.C. & Binkley, D., 1994. Effect of Management on Water Quality in North American Forests. General Technical Report RM-248. Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colo. Butler, B.J.; Hewes, J.H.; Dickinson, B.J.; Andrejczyk, K.; Butler, S.M.; & Markowski-Lindsay, M., 2016. USDA Forest Service National Woodland Owner Survey: A Technical Document Supporting the Forest Service Update o f the 2010 RPA Assessment. Resource Bulletin NRS-99. USDA Forest Service, Newtown Square, Pa. Caldwell, P; Muldoon, C.; Ford-Miniat, C.; Cohen, E.; Krieger, S.; Sun, G.; McNulty, S.; & Bolstad, P.V., 2014. Quantifying the Role o f National Forest System Lands in Providing Surface Drinking Water Supply for the Southern United States. General Technical ReportSRS-197. USDA Forest Service, Southern Research Station, Raleigh, N.C. de la Crtaz, A.L & Barten, P.K., 2007. Land Use Effects on Streamflow and Water Quality in the Northeastern United States. CRC Press, Boca Raton, Fla. https://doi.Org/10.1201/9781420008722. Ernst, C., 2004. Protecting the Source: Land Conservation and the Future o f America's Drinking Water. AWWA and The Trust for Public Land, Denver. Fedinick, K.P; Wu, M.; & Olson, E.D., 2017. Threats on Tap: Widespread Violations Highlight Need for Investment in Water Infrastructure and Protections. Natural Resources Defense Council, New York. Furniss, M.J.; Staab, B.P; Hazelhurst, S.; Clifton, C.F.; Roby, K.B.; llhardt, B.L.; ED 002061 00160092-00006 Larry, E.B.; etal. 2010. Water, Climate Change, and Forests: Watershed Stewardship for a Changing Climate. General Technical Report PNW-GTR-812. USDA Forest Service, Pacific Northwest Research Station, Portland, Ore. Holmes, T.P; Vose, J.; Warziniack, I ; & Holman, B., 2018. Forest Ecosystem Services: Water Resources. In Trees at Work: Economic Accounting for Forest Ecosystem Services in the U.S. South. General Technical Report SRS-226. USDA Forest Service, Southern Research Station, Asheville, N.C. Pimentel, D.; Berger, B.; Filiberto, D.; Newton, M.; Wolfe, B.; Karabinakis, E.; Clark, S.; Poon, E.; Abbett, E.; & Nandagopal, S., 2004. Water Resources, Agriculture, and the Environment. Report 04-1. College of Agriculture and Life Sciences, Cornell University, Ithaca, N.Y. Sun, G.; McNulty, S.G.; Myers, J.A.M.; & Cohen, E.C., 2008. Impacts of Multiple Stresses on Water Demand and Supply Across the Southeastern United States. Journal of the American Water Resources Association, 44:6:1441. USDA (US Department of Agriculture) Forest Service, 2012. Future o f America's Forest and Rangelands: Forest Service 2010 Resources Planning A c t Assessment. General Technical Report WO-87. USDA Forest Service, Washington. USEPA (US Environmental Protection Agency), 2008. Factoids: Drinking Water and Ground Water Statistics for 2007. http://nepis.epa.gov/Exe/ZyPDF.cgi/ PI 00N2VG. PDF?Dockey=P100N2VG.PDF (accessed November 2017). USGS (US Geological Survey), 2018. Hydrologic Unit Maps. https://water. usgs.gov/GIS/huc.html (accessed February 2018). Warziniack, T.; Sham, C.H.; Morgan, R.; & Feferholtz, Y., 2017. Effect of Forest Cover on Water Treatment Costs. Water Economics and Policy. 3:4:1750006. https://doi.Org/10.1142/ S2382624X17500060. Weidner, E. & Todd, A., 2011. From the Forest to the Faucet: Drinking Water and Forests in the US. USDA Forest Service, Washington, www.fs.fed.us/ ecosystemservices/pdf/forests2 faucets/F2F_Methods_Final.pdf (accessed November 2017). AW W A RESOURCES Protecting Drinking Water at the Source: Lessons From US Watershed Investment Programs. Gartner, T.; DiFrancesco, K.; Ozment, S.; Huber-Stearns, H.; Lichten, N.; & Iognetti, S., 2017. Journal AWWA, 109:4:30. Protecting Forested Watersheds Is Smart Economics for Water Utilities. Gartner, T.; Mehan, G.T. Ill; Mulligan, J.; Roberson, J.A.; Stangel, P.; & Qin, Y., 2014. Journal AWWA, 106:9:54. These resources have been supplied by Journal AWWA staff. For information on these and other AWWA resources, visit www.awwa.org. HYMAX GRIP LARGE DIAMETER 16" Sierra Club v. EPA 18cv3472 NDCA CLAGGETT & MORGAN | JULY 2018 * 110: 7 | JOURNAL AWWA 47 Tier 5 ED 002061 00160092-00007