Local Water Resources/Issues
Environmental and Technology Studies
Carleton College

Emily Miller, Margie Sollinger, Eric Shoemaker

Local Resources and Outputs:

Lyman Lakes:

Lyman Lakes are perhaps Carleton's most visible water resource. These two man-made ponds (Upper and Lower Lyman) comprise approximately 8 acres of surface area on the lower Spring Creek watershed. The presence of the lakes is valuable to the college as a recruiting tool and from an aesthetic standpoint. Photographs of the lakes can often be found in official college literature. Although the lakes were also once valuable from a recreational standpoint (swimming, fishing, etc.) siltation problems have caused them to fall into disrepair over the past few decades. Much of the problem lies in the fact that the lakes are not naturally lakes, but rather, wetlands. This fact, combined with the high sediment load of Spring Creek acts to "fill-in" these impoundments, making them less and less lakes every year. To combat this, Carleton recently dredged the lakes (Upper and Lower) to depths of 10ft and 15ft respectively. The college also installed a settling system in an effort to keep high amounts of sediment from entering the system. The hopes are that these measures will allow the lakes to remain lakes and thus serve the diversity of functions which they once did.

The Cannon River:

The Cannon River is another visible water resource. From its headwaters at Rice Lake west of Faribault, MN the Cannon's course takes it approximately 90 miles East-Northeast before it joins the Mississippi north of Red Wing, MN. About a mile and a half of this course flows through Carleton property. The Cannon is a medium-sized river with an average annual flow of approximately 175 cubic feet per second (cfs). Three main towns: Faribault, Northfield, and Cannon Falls can be found along the river with much of the rest of the watershed draining agricultural and remnant forest/prairie landscapes. The watershed and river itself are biologically diverse environments that support a wide variety of flora and fauna including almost every species of fish that swims in Minnesota waters and species of federally-listed endangered mussels.

The Spring Brook Watershed:

The Spring Brook watershed drains about 8 square miles of land to the South-Southeast of campus. About 3/4 of a mile of the creek flow through campus, entering in the Upper Arb. and flowing into the Cannon below Lower Lyman lake. The Spring Creek watershed has been heavily affected over the years by agriculture, and more recently, residential development. The overall water quality of the creek has been compromised by siltation, herbicide/pesticide runoff, high phosphate content due to the use of agricultural/golf course fertilizers, and temperature pollution due to upstream settling ponds.

Well System:

Carleton's water supply is reliant on the Jordan aquifer pumped via the college's own well system. These water sources have been found to be of excellent quality on a consistent basis. Carleton's water is treated on-site through chlorination. Although Carleton is not required to check water quality more often than on an annual basis, water samples are taken and examined daily to ensure good quality. Due to the abundance of water resources in the state of Minnesota, Carleton does not consider itself in danger of water shortages. In the unlikely event of Carleton's water supply being compromised, the college relies on the City of Northfield water system as a back up, and has the ability to easily tap into Northfield's supply through electrical connectors.

Current Issues:

New Settling Ponds:

The purpose of a settling pond (a.k.a. holding/detention/retention ponds) is to act as a concentrating filter device. It functions by trapping all of the run-off water from parking lots and hillsides. Once concentrated in the pond, oil, sediments and particulate matter "settle-out" to the bottom of the pond. The cleansed water then leaves the pond (how does it leave-flooded out?) and enters into the rivers, lakes and streams.

Two holding ponds currently exist at Carleton, and one more is scheduled for construction. Already in existence is the retention pond for the Recreation Center's run-off. This pond is located in the lower Arboretum, and filters out sediments and chemical run-off before the water enters the Cannon River. A second retention pond services the water from the stadium parking lot area, and is located next to Allen House. The previous method used to cleanse the run-off before it entered into the Cannon River was to simply let the water run through the grass, hopefully relieving it of oil and sediments before it reached the river. This practice is no longer in use due to a law mandating the construction of parking lot curbs and gutters. Carleton also uses vertical holding tanks, or storm septers, which remove 80-90% of all particulate matter from storm water run-off. The septers are 12 feet in diameter, and are located on the Evans' side of lower and upper Lyman Lakes. Finally, a retention pond is slated to be constructed next to the Maple Street Parking area, South of Meyers dormitory. The holding pond will utilize more natural methods of filtration. Big blue-stem (a native prairie grass) will be planted at the edges of the pond, serving as a primary filtration mechanism. The second phase will be the usual settling out of sediments to the bottom of the pond.

The most obvious problem with the holding ponds, as evidenced by the 2001 flooding, is that they are non-functional when there is too much water running through. That is, when the water levels are higher than the ground level of the pond edges, the contaminated water will simply run over the pond area directly into the tributaries. Other concerns we have are in regards to what is done with all of the settled materials. Is it removed from the ponds? Are the ponds lined to prevent groundwater contamination? Is there a back up plan in the works, in the event that flooding occurs again?

Lyman Lakes: Habitat Vs. Reflecting Ponds:

The exact function of Lyman Lakes has long been a topic of debate at Carleton. There are some (especially within the scientific community) who would like to see the lakes restored to the wetland habitat that they once were. There are others in the administration who feel that the lakes are an integral fixture of the Carleton landscape. Part of the problem surrounding this debate involves the siltation problems which plague the system. Now that the lakes have been dredged and siltation mitigation measures have been put in place, the college is presented with a unique opportunity for restoration of the aquatic environment. Work is currently being done to restore native fish species to the lakes. This will be an asset to both the college and the local community as well as furthering the college's mission of restoring native species through its work in the Arboretum.

Floodplain Development:

Heavy spring rains have noticeably altered the floodplain of the baseball field near West Gym, calling for an alternative location for the baseball diamond due to the erosive effects of the rain and storm water runoff. Plans are in place to relocate the baseball diamond to a location adjacent to the frisbee and rugby fields near the Hill of Three Oaks. Although Bell Field is also situated on a floodplain along the banks of Spring Creek, the soccer and softball diamond will not be moved. Plans have been proposed to develop an irrigation system of Bell Field using storm water drainage from Evans Hall, but these plans will not be finalized until renovation of the dorm begins.

Pesticide/Herbicide Use:

Carleton uses an assortment of pesticides, herbicides, and fertilizers. A corn gluten fertilizer is used on all campus athletic fields in the spring- the only location where fertilizer is used. The corn gluten-based fertilizer is spread out across the fields, dissolving into the soil. Grasses on other locations grow too quickly for other fertilizers to be effective. This method has been found to be effective and safe. Herbicide and pesticide use is limited mainly to athletic fields, but chemicals such as RoundUp and Tordon are used in the Arb and on a few other campus locations to combat broadleaf weeds. To curb the abundant bee population in the fall, an organic insecticide is sprayed in key campus locations. Elm trees are injected to prevent Dutch Elm disease, and this procedure does not contaminate the water system because it is injected directly into the trunk of the trees.

Goals and Recommendations:

Sustainable Design:

Newly constructed buildings (and future buildings) all contain low-flow toilets and low-flow shower heads in an attempt to decrease the amount of water used. Some campus housing features showers that have a handle that is pulled out and pushed in so that temperature can be set when the shower is turned on. This makes it easier for users to turn on and off the water while lathering up than with many current showers on campus. If used in this manner, this feature could decrease the consumptive waste of water on campus. Staff in facilities hope to implement these showers in additional campus locations.

Water Quality:

Although the United States is endowed with abundance surface and ground water, our clean water supply is far from unlimited. Especially in Minnesota, the land of 10,000 lakes, it is easy to let the issue of water quality and conservation slip to the bottom of the priority list. Carleton is no exception, putting energy and indoor air quality at top of its to-be-greened list (Richard Strong, personal communication).

Native Species:

As part of an effort to bring the restoration ecology philosophy of the Arboretum to the campus, native prairie species are replacing turf grass on the campus hillsides, around new construction and parking lots. As filtering buffer zones and erosion controls, these native species will be planted along the new townhouses, surrounding Lyman Lakes, and around the proposed Maple Street Parking retention pond. Native plants will represent 90% of the species planted around the new townhomes, and 100% of those planted in the other two areas.

For the Future:

• Promote water awareness on campus and make it an administrative priority.
• Analyze student consumption in more depth.
• Develop methods to evaluate current water systems.
• Create a back up filtration system, in the event of flooding.
• Development of closed-loop water systems (e.g. gray/black water use, use storm water for athletic field irrigation).
• Effects of athletic field pesticides on Cannon River and Spring Creek.
• Status of pipe system (i.e., efficiency, age, maintenance).

Sources:

• Richard Strong, Director of Facilities
• Dennis Easley, Superintendent of Grounds
• Wayne Beierman, Engineering Supervisor
• Mary Savina, Professor of Geology