Kris Osterloh
2/27/08
English 145
Steven Marx
Sustainability at Cal Poly: Water Conservation
Conservation and sustainability of natural resources have become popular topics for college students to get involved in. The most popular subjects are the conservation of the old growth forests, oil, and the atmosphere. One overlooked resource is arguably the most important to life on our planet: water. Most people ignore water for two reasons: there is so much water, 70% of our earth’s surface is covered in it, and water cannot be destroyed. Water only changes phases and travels through the Hydrologic cycle. The water in your glass is the same water that was on this earth 4 billion years ago.
The topic of water conservation first struck me when I was at rugby practice earlier this month. Several of our practices had been relocated because rain had closed down our fields. When we resumed practice the next week our whole team noticed that the fields were still extremely wet even though enough time had passed and the weather had been warm enough that the fields should have been mostly dry. Initially there was only one reason that came to our minds; they had still been watered. I asked myself, who would water a wet field, especially a sports field which already suffers from compaction of the soil. I decided to investigate the management of the sports fields at Cal Poly. After doing some research on the ASI sports fields I soon realized that both management and planning are critical to conserving Cal Poly’s water.
All water must come from a source, usually a river fed reservoir. Cal Poly gets most of its water from Whale Rock Lake, the rest comes from wells. Of Whale Rock’s 40,662 Ac-Ft capacity, Cal Poly has rights to 13,554 Ac-Ft of water each year. An Ac-Ft is the amount of water needed to cover an Acre of land with a foot of water, just under 326,000 gallons. Whale Rock Lake continues to recharge itself and supply Cal Poly, but with inevitable global climate change in the future that supply may dramatically drop or run dry entirely. The climate of San Luis Obispo is considered Semi-Arid because of our low annual precipitation. As with most Semi-Arid climates, annual precipitation has a high variability. Our annual average rainfall is about 21 inches, but we rarely see that exact amount of rain. Generally the central coast has alternating years of moist and dry winters. One year we will only get around 8 inches, then the next year rainfall might exceed 40 inches. This variability of water supply puts great stress on Whale Rock Lake because during times of drought the water level can drop tens of feet in a single year.1
The soils of Cal Poly require proper water management to avoid gradation and sedimentation. Sedimentation is the process of running water picking up particles as it moves. When water picks up particles in a stream bed and starts to erode the bed down to bedrock, it is called gradation. Cal Poly is located on the slopes of hills which are composed of a significant amount of serpentinite, which is classified as a low grade metamorphic rock with a high Magnesium content. The serpentinitic soils spread throughout the region are chemically unstable, making them easily eroded and transported by running water.2 If Cal Poly wastes its water, then the excess water becomes runoff, picking up particles of our precious soil and transporting it out to sea. What’s left of the soil is very thin and low in nutrients because most of the nutrients are contained in the top few inches of soil.
To prevent the degradation of our precious top soils, proper water management must be employed. In order for Cal Poly to sustainably manage its water supply, it must ensure that the both the quantity and quality of water entering and exiting Cal Poly remain constant or increase over an indefinite period of time. By reducing its demand for water, Cal Poly has a greater chance of ensuring a continual supply of water by not over draining Whale Rock Lake. Not surprisingly, I am not the first person to be concerned about Cal Poly’s effort to conserve water. Already Cal Poly has gone through tremendous lengths to reduce its water consumption. Already aware of the irregular recharge of Whale Rock Lake, Cal Poly has constructed a Master Plan to make Cal Poly “an environmentally responsible campus that demonstrates high regard for bio diversity and energy conservation”.3 One of the ways Cal Poly is conserving water is through the use of Waterless Urinals.4 Conservation of water in the restrooms is critical because the average student uses about 40 gallons of water flushing toilets every day.5 These devices are growing in number around the campus and can each save thousands of gallons a year, especially in the busiest bathrooms. Another way that Cal Poly is protecting its water supply is efficient irrigation of its farmlands. Micro sprinklers and reusing groundwater that has percolated past the reach of plant roots has helped Cal Poly reduce its relative water use throughout the campus.4 Since Cal Poly has such an extensive agriculture program and the second most land of any California University, evaporation plays an extremely large role in its water consumption. To combat evaporation, watering of plants, fields, and farmlands is done in the morning when evaporation rates are lowest.
Although the watering takes place at the best time of day to conserve water, the system can still be improved. Every day as you walk through campus in the early morning, the sidewalks near lawns and landscaped areas are covered with water. Although this little water may seem insignificant, if you combine the wet sidewalks all over campus they waste a large amount of water over time. The sprinkler system needs to be improved to ensure that the sprinklers are only spraying water on the areas that need water. The flow must also be adjusted so that sprinklers do not dump water on an area faster than it can infiltrate into the ground. Most of Cal Poly’s landscape has some sort of slope, so the access water flows off of the vegetation and onto the sidewalk, taking important nutrients with it. An easy way to combat excess water runoff is to dig small trenches around the area to collect the water.
Large sources of wasted water are sports fields. Since they are relatively flat sports fields have less runoff than most of the campus, but their large, open size and lack of tree cover gives them a much higher evaporation rate. Evaporation can be devastating to soil. All freshwater contains a minute amount of salt. Constant evaporation creates a buildup of salt called salinization. Salinization can build salt up to such high levels that the ground will become white and sterile, producing no vegetation. The only way to combat salinization is to use water to flush away the salt from the land.
Adding to the evaporation is the condition of many of the sports fields around campus. Constant practices and games have compacted the soil in many places and have torn up much of the grass around the fields. Compaction slows or prevents water from percolating into the ground and the decreased grass increases the evaporation. The largest waste of water occurring on these fields is during the winter rainstorms. Rainwater fills the soil to field capacity and then begins to puddle on the surface, sometimes creating ponds over 20 feet wide. The ground underneath the fields has a slow percolation rate causing the excess water to drain ever so slowly. This viciously slow percolation causes the fields to be muddy for weeks after periods of rainfall, despite being located in the part of the continent with the highest evaporation rates.
Although I had initially assumed that the fields were still watered after rainstorms, I discovered through my research that I was wrong. I had overestimated the fault of the field management system and underestimated the severity of the field’s poor drainage. The field’s water system is hooked up to a computerized irrigation system connected to a weather station, and is adjusted both electronically and manually every day.6 Unfortunately, the field only has a slope of 1% to ½% and water must travel nearly 1,000 ft to be drained at the south end of the fields. As it travels, the top water is evaporated and capillarity pulls subsurface water back up to the top to replace it resulting in continuously muddy conditions.
These fields represent a perfect example of how important planning is to water conservation. No matter how well managed a site may be, planning ultimately determines its peak water efficiency. The sports fields need “a major subsurface drainage system installed”6 to function properly. Proper planning and drainage will prevent salinization and allow the fields continued usage for many years to come.
Cal Poly has been effective in its efforts to sustainably manage its water resources. Through rigorous testing water quality has been maintained and pollutants have been properly checked to be below the acceptable levels. Now Cal Poly must finish its conservation of water quantity. As Poly Canyon Village nears completion and enrollment continues to rise, Cal Poly will need a lot more water. To combat the increase in water demand, we must drastically decrease the amount of water we use now. Although there is much work to be done, Cal Poly is slowly increasing its conservation of our precious water every year. Soon all weather fields will replace three of our current grass fields. These new fields do not need to be watered and will not be damaged by heavy use like the current fields. Each of these steps brings Cal Poly’s water a little closer to becoming completely sustainable.
Works Cited
1. Dingus, Del. “Cal Poly Soil and Water Resources”. Cal Poly Land. March 3 2008. http://polyland.calpoly.edu/topics/soils/index.html
2. Chipping, David. “A Geological Tour of Cal Poly Canyon”. Cal Poly Land. March 4 2008. http://polyland.calpoly.edu/topics/Geology/index.html
3. “Building for Sustainability” California Polytechnic State University. March 16 2008. http://www.facilities.calpoly.edu/campusprojects/projects/sustainability/Pages/masterplan.htm
4. Multari, Mike. “Sustainability at Cal Poly Faculties and Operations” 2006. March 4 2008. http://www.facilities.calpoly.edu/campusprojects/projects/sustainability/SusInd06.pdf
5. Getis, Judith. “You Can Make a Difference” 1999. McGraw-Hill. March 3 2008
6. Mead, George. Email Interview. March 5 2008.
7. Dorfman, Jason. Kellas, Kristy. Menzel, Scott. Ngo, Vivian. Powell, Sarah. Webb, Shawn. “Aquatechnics”. March 4 2008. http://polyland.calpoly.edu/topics/stewardship/studentsites/EDES2003AquaTechnics/title.htm