Urbanization is a double-edged sword, and Utah has seen its share of its benefits and blights. In Cache Valley, for example, 1400 North is undergoing a rural-to-retail transformation. The street, which used to be bordered by empty land, alfalfa fields, and grazing cattle, is now the newest retail hotspot in town, home to such retailers as Lowe’s hardware, Ruby Tuesday, Lee’s Marketplace, and a dozen other new restaurants and stores. The new development is providing needed economic and retail growth to the valley, but it also brings with it many new challenges.

Utah State University researchers Nancy Mesner and Robert Gillies have been working to tackle one of these challenges, using satellite images to study the effects that development has on water, arguably Utah’s most valuable natural resource.

“In an area that is becoming more urbanized, a lot of things change,” says Mesner. “Urbanization affects not only how the valley looks but also how much water is soaked up in the soil and how much runs off. When water doesn’t soak into the ground, pollutants can be washed into streams and lakes.”

Mesner’s research concentrates on working with land developers in high-growth areas to teach them how development can be more efficient in conserving and protecting water resources. She has teamed up with Gillies, who specializes in using remote sensing to extract information from satellite images about the land and the water in Cache Valley and other areas in the country.

Together, Mesner and Gillies, both of the Department of Aquatic, Watershed, and Earth Resources, examine impervious surface areas (ISA) such as asphalt, cement, and rooftops, where rainwater does not soak in, but instead runs off. They measured the quality of the water that runs off developed parts of land in Cache Valley.

In the past, planners and researchers used aerial photographs to measure and map urban areas, Gillies says. Not only was this time consuming, but it was also expensive.

Satellite imaging is a technology that is a lot cheaper, easier, and faster in measuring the extent of impervious surface areas, Mesner says. Imaging is done by looking at the way light bounces back off the ground’s surface. Researchers can then interpret the light that comes back and identify what is at the ground surface.

“The beauty of satellite imaging is that you can obtain really current information and can easily update it, which is by far more difficult with other methods,” Mesner says.

For their study, a graduate student Penny Rieke-Arentsen, working with Gillies and Mesner, obtained the satellite images covering Cache Valley, and used the imagery to map the amount of impervious surface area in the valley. Rieke-Arentsen then related the urbanization variability (as a percentage of ISA) with changes in water quality.

To look at the urban water quality, which measures the type of pollutants urbanization brings into the water, the researchers measured pollutants in water samples they collected from the canals of Logan, Utah during storm events. Mesner now uses the results of the ISA work to show land developers how to protect certain types of areas.

Gillies says Cache Valley has been ideal for the study because of its increase in development and also because the canal systems that run parallel to the mountainside were ideal catchments for urban water runoff.

“We were able to use these canals, since they intercept runoff water. It was like someone built them just for our experiment,” says Mesner.

The canals Mesner and Gillies studied yielded water samples that violated water quality criteria for metals, bacteria, nutrients and sediments. Mesner says she is hoping to educate land planners and the public about the importance of conserving water around their homes in order to reduce the pollutants that are loaded in Utah’s water reservoirs.

“There are people who will let their sprinklers water the sidewalk, instead of the lawn, or who will pour oil down storm drains, not knowing that those drains will lead directly to streams or irrigation canals,” Mesner says. “Those people do not realize how much these activities can affect the water.”

The major finding of Mesner and Gillies’ research is that a relationship exists between the amount of impervious surface cover in an area and how polluted the water becomes.

In addition to their research, Mesner has developed an outreach program to educate the public of Cache Valley about water quality and conservation. She and graduate student assistant Andree’ Walker have developed a curriculum for ninth-grade science teachers to educate students about the importance of water usage. They have also visited schools and provided hands-on activities to teach children about how urbanization and other changes on our lands can affect our water.

Gillies and Mesner are trying to “bridge the gap,” by quantifying urbanization in terms of water pollution. Mesner said she wants to let people know that because of urbanization, Cache Valley may lose fisheries and some recreational uses. Gillies and Mesner also say they want to show city planners how to apply technological advances in mapping to manage the land and growth better in order to assess and ultimately to mitigate those pollutants that enter our water resources.

“This is a huge area of interest for most developing areas,” Mesner said. “This research really affects any urban area.”

- Erin Didericksen