4.0 Conservation and Maintenance of Soil and Water Resources Soil and water are the foundation for all other forest resources. Soil, which has both living and nonliving elements, holds water between rainstorms and stores nutrients for plants and animals; it also acts as an anchor for vegetation and a seasonal or permanent home for a variety of burrowing animals, insects, and microscopic creatures. Soil conservation means maintaining site productivity and soil resource functions. Even though it can be formulated and restructured to support plant growth, soil is not considered a renewable resource because it takes thousands or even millions of years to develop. Water resources include the physical features, habitat, and inhabitants of lakes, streams, and wetlands, as well as water itself. Forests and trees, whether urban or rural, help reduce storm water runoff, filter pollutants, store water and nutrients, clean and cool water, protect municipal water supplies, reduce flooding, replenish groundwater and provide fish habitat. Water quality depends upon the extent to which the watershed from which it comes is disturbed by pollution, bacteria and other factors. The quality of Iowa’s water is only as good as the quality of the soil that filters it. The topsoil that once grew prairies, forests and wetlands and which once purified water across the state has been eroding away since the time the state was first settled; in fact, half of the topsoil that existed prior to statehood has been lost in most of the state’s sloping cropland. This productive soil has been washed into streams and blown across fields and ditches; as a result of this, aquatic systems have been choked and fertilizers and pesticides have damaged water sources and other natural areas.41 4.1 Iowa’s Water Programs and efforts designed to improve water quality are crucial for maintaining safe, healthy drinking water. Forest riparian buffer and bottomland hardwood tree planting practices, funded through the Conservation Reserve Program, are one way of using sound forest management practices to promote and improve water quality. In Iowa, however, the importance of tree planting and forest management practices to improve water quality is often overlooked. Emphasizing efforts in watersheds that provide domestic water supplies and watersheds containing impaired waters are good places to prioritize reforestation activities. While certainly not pristine, Iowa lakes and streams may be cleaner than in the early 1900’s, when they were polluted with sewage and industrial wastes. Federal studies of Iowa’s surface waters in recent years have noted contaminants such as fertilizer, agricultural chemicals, industrial wastes, sewage and livestock manure. The need to remove excess water as quickly as possible to promote high yielding food crops has led to the tiling of millions of acres of agricultural crop land; there are currently over 800,000 miles of drainage tile lines, which is 7 times the length of Iowa’s current road system.42 167 41Stone. 42Stone. The removal of natural systems along water corridors leads to negative long-term consequences. The channelization of streams to increase cropland has reduced the water holding basin of most streams in Iowa and increased the likeliness of flooding in many areas across the state. This has led to a decrease in the amount of stream length available for water holding during rain events. During periods of heavy rainfall, areas with reduced storage capacity overflow, Photo by Photographic Services, University of Iowa. causing flood damage to agricultural fields and property. Remedies for such problems include wetland restoration and establishment of riparian buffer strips, which can increase water holding capacity during heavy rain events. Another consequence of stream channelization is increased water velocity, which accelerates the process of stream bank cutting. When these channelized streams meet natural, meandering streams, the increased energy is dissipated, but not before damaging the interface with the natural system. Over time, damage to the natural system results in decreased habitat for both terrestrial and aquatic creatures. More time and money are required if monitoring of livestock wastes, urban runoff, pesticides, sewage facilities and non-point pollution is to be effective. River and lake protection can be achieved through watershed safeguarding, wetland restoration, and channelization prevention. The most economical way to address the problems created by improper land and water use is to teach landowners about the ways that their habits can affect the functioning of natural systems, and how damage to such systems can come back to harm them in the future. According to NOAA, Iowa receives an average of 34 inches of rainfall each year; about two inches of this evaporates from trees and plants and returns to the atmosphere, four inches runs directly into rivers and lakes and another two inches soaks into the groundwater system. The Photo by Gary Hightshoe, Iowa State University. rest is available for plants, trees and agricultural crops that produce valuable crops for the landowners that own them.43 Before Iowa’s permanent vegetation was removed, water was usually slowly filtered and absorbed by soil structure that was seldom disturbed. Some of the water moved through the soil profile to underground aquifers providing clean drinking water that citizens still benefit from today. This clean source of water has become more important as the difficulty and costs of cleaning surface water increases. Now surface water carries fertilizers, chemicals, soil, and other pollutants due to the over 60% of the land under agricultural production and 700 communities not having adequate sewage systems.44 The costs to correct and prevent problems with water quality as a result of land use decisions will continue to follow each generation that lives in Iowa. 168 43Stone. 44 <www.water.iastate.edu/Documents/SWCC_Soil_Water.pdf>. April 15 2010. There are two sources of water pollution: point source pollution, which is poured directly into a water source from a pipe or other device, and nonpoint source pollution, such as sediment, nutrients, and bacteria, which washes into water sources from fields and other areas. While point source solution can be a problem, most water quality problems in Iowa are caused by nonpoint source pollution. Such pollution comes from watersheds, which are areas of land that drain into lakes or streams. To improve Iowa’s water quality, watersheds need to be stabilized with permanent native vegetation to keep sediment, nutrients and bacteria from washing into streams and lakes. Iowa farmers annually apply more than 3 billion pounds of chemical fertilizers and 45 million pounds of pesticides to agricultural fields. It is therefore no surprise that agricultural pesticides are detected in nearly every sample of rainfall taken during the growing season, in 26 percent of groundwater samples and in 78 percent of surface waters samples.45 There have been a lot of studies reviewing the impact of agricultural chemicals on human health and the environment. Although the results vary, there are few who dispute that dispersal of these chemicals is widespread. A computer modeling software program called SPARROW gives regional interpretations of water-quality monitoring data. The model relates in-stream water-quality measurements to spatially referenced characteristics of watersheds, including contaminant sources and factors that influence terrestrial and aquatic transport. SPARROW empirically estimates the origin and fate of contaminants in river networks and quantifies uncertainties in model predictions. Figure 4.1 shows which states contribute the greatest amount of nitrogen and phosphorus to the Gulf of Mexico. Figure 4.1 Estimates of Nitrogen & Phosphorus Contributions to the “Dead Zone” in the Gulf of Mexico. Source: USGS, water.usgs.gov/nawqa/sparrow/gulf_findings/by_state.htm. Nitrogen from farm and lawn fertilizers, livestock manure and municipal and industrial wastes are expelled into Iowa’s rivers and eventually travel down the Mississippi River system. The accumulated discharges of these pollutants into the Gulf of Mexico have reduced the amount of oxygen there, which has led to the development of the hypoxic zone or “Dead Zone”. Roughly the size of New Jersey, this area gets its name from the near-complete lack of shrimp, fish and other marine life found there during the spring and summer months.46 45Stone. 169 46Roach, John. “Gulf of Mexico ‘Dead Zone’ Is Size of New Jersey.” National Geographic News. May 25 2005. <news.nationalgeographic. com/news/2005/05/0525_050525_deadzone.html>. The best way to improve Iowa’s waterways is to permanently establish buffers of a certain width around lakes and on both sides of streams. The width of these buffers would depend upon soil type and land slope. Permanently establishing vegetation like trees along all water bodies and corridors would provide multiple long-term benefits to humans and wildlife. Though installation of buffers between agricultural land and streams can help to decrease the amount of harmful chemicals that Source: EPA, www.epa.gov/gmpo/nutrient/hypoxia_pressre- reach the water supply, tile systems lease.html. can reduce the effectiveness of buffers by simply causing polluted water to flow underneath them. One solution to this problem is to break tile lines within buffers and allow the water to drain into natural or man made wetlands, which can then filter it before it flows back into streams. This would improve Iowa’s streams while still allowing for the removal of excess water from cropland. Forested wetlands are beneficial for improving water quality in the watersheds where they occur. Figure 4.2 shows the locations of forested wetlands in Iowa. The map was created using 2002 aerial photography as well as 1984 National Wetlands Inventory information provided by the U.S. Fish and Wildlife Service. Figure 4.2 Forested Wetlands in Iowa. 170 Source: Kathryne Clark using satellite land cover from 2002 and National Hydrologic dataset. Toxic byproducts from human activity and excess silt take their toll in the form of fish kills.Photo by Ron Johnson.