Executive Summary
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This report presents a discussion of the source water watersheds for Little Rock, Arkansas, and its environs: Lake Winona and Lake Maumelle Watersheds. Lakes Winona and Maumelle are important sources of water supply for the roughly 400,000 people[i] in the Little Rock metropolitan area. The health of the surrounding ecosystems is vital to maintaining water quality.
This report includes a description of each watershed’s current health, threats to water quality, and the ecosystem services benefits that the watersheds provide. In addition, we provide estimates for the economic value of these natural capital assets. By shedding light on the importance of these watersheds to the economic health of the region, these estimates provide the foundation for better-informed decisions regarding watershed management activities.
Central Arkansas Water (CAW) owns and manages Lakes Winona and Maumelle for drinking water supply, serving as a dedicated steward that combines careful management practices with targeted local advocacy to ensure the long-term health of the region’s water supply. In 2007, Central Arkansas Water formally adopted the Lake Maumelle Watershed Management Plan, but no comparable plan exists for Lake Winona. The management plan includes guidelines for wildfire management practices, a watershed protection fee, and updates to zoning codes.
The lakes and the ecosystems that surround Lakes Winona and Maumelle represent an enduring asset of the region, one that has served for decades to provide high quality water at a cost below state and national averages[ii]. These ecosystems also provide other services to residents of the area and beyond: cleaning the air, reducing erosion, supporting sustainable timber production, offering beautiful places to recreate, and more. With proper care and maintenance, these natural systems will generate tremendous value for Central Arkansas and its residents far into the future.
Both lakes, however, face threats to water quality. Lake Winona is fairly well protected from development as it is surrounded by the Ouachita National Forest and the Winona Wildlife Management Area. The ecosystems around Lake Maumelle are similar, but disturbances such as clear-cuts or agricultural and residential plots are more common. Lake Maumelle is threatened by new development, existing uses such as harmful residential and agricultural runoff, increased sedimentation and erosion issues from the timber industry, and risks of hazardous spills from a nearby oil pipeline. Both Lake Maumelle and Lake Winona face risks from wildfire and erosion due to historically unmanaged forests.
The threats to these watersheds pose serious risks for the ecosystem services that provide direct benefit to CAW: water capture, conveyance, and supply; water quality; water storage; soil retention; soil formation; and disaster risk reduction. Many more services benefit both the utility and local communities, including: air quality; aesthetic value; energy and raw materials; habitat and nursery; and recreation, among others. This study values six land cover types that provide a total of 19 distinct ecosystem services to the Maumelle and Winona Watersheds.
To estimate the value of ecosystem services produced by the Maumelle and Winona Watersheds, this study uses Geographic Information Systems (GIS) data to identify land cover types, and valuation studies from Earth Economics’ Ecosystem Valuation Toolkit (EVT) to calculate values. This analysis employs benefit transfer methodology (BTM) to derive high and low annual per-acre dollar values for each ecosystem service across each land cover type. The primary ecosystem services for CAW are: Water Quality; Water Storage; Water Capture, Conveyance, and Supply; Disaster Risk Reduction; Soil Formation; and Soil Retention.
At the most conservative estimate, the flow of value to the local and regional economy from the Lake Winona Watershed ranges from approximately $3.6 million to $26.4 million for the primary benefits alone. The annual co-benefits for Lake Winona provide additional value between approximately $11.6 million and $129.4 million per year. For Lake Maumelle, the larger of the two watersheds, the annual value of primary benefits is between $19.7 million and $91.7 million. The annual co-benefits from the Lake Maumelle Watershed provide an additional $44.7 million to $380.6 million. The range of values reflects the inherent uncertainty in BTM and accounts for variations in ecosystem health, cultural differences, and the dynamic nature of supply and demand over time.
Lakes Winona and Maumelle both provide the regional economy with significant value in the form of ecosystem services. As with any valuable asset, it is prudent to take steps to invest as necessary to maintain and enhance the value of the asset over time. Active investment by CAW in its assets around Lake Winona and Lake Maumelle can be viewed as the ‘ounce of prevention’ necessary to insure ecosystem value against the ‘pound of cure’ costs associated with erosion and subsequent sedimentation, degraded water quality from runoff, or remediation. Robust ecosystems are more resilient to environmental changes, and planning that incorporates ecosystem services value reduces the risk of loss of life and property as well as exposure to expensive mitigation costs that could burden local agencies and ultimately tax and ratepayers.
Natural assets are not indestructible, and they are under significant pressure particularly around Lake Maumelle. Beyond certain thresholds, they will lose their ability to provide value. Although Lake Winona does not yet face the same pressures as Lake Maumelle, CAW should take action in implementing beneficial management practices today. The following actions are recommended for the watersheds:
- Continue investment in the Lake Maumelle Watershed.
- Invest in a watershed management plan for the Lake Winona Watershe
- Continue to strengthen collaboration with local stewards, including land trusts and private landholders.
- Research potential funding streams for the watersheds. Options may include carbon credit markets or wetland mitigation banking.
- Build community awareness and support for watershed management.
With sufficient care and investment in maintenance for these watersheds, Lake Winona and Lake Maumelle will continue to provide high water quality and other services that support quality of life for the residents of Central Arkansas.
[i] Central Arkansas Water. About Us. Available at: http://www.carkw.com/about-us/ (retrieved September 2015)
[ii] Central Arkansas Water. Rates. Available at: http://www.carkw.com/customer-service/rates/ (retrieved September 2015)