Sustainable water resource management is broadly defined as the use of water resources “in a way that meets the needs of the present without compromising the ability of future generations to meet their own needs” (Brundtland Commission 1987).
Today, protecting water resources is the single greatest challenge faced by many states, and the most critical step toward ensuring the current and future well being of communities across the country. Threats to water resources affect the economic viability of communities nationwide. As a result, state and local governments are increasingly focusing on how best to preserve, protect, and restore these resources.
Like many other communities across the country, Winter Haven, FL—a city of 34,400 people in Polk County—is working to ensure that its future water needs are met, including water for residents, business, industry, agriculture, and the environment. An important part of the challenge for Winter Haven and other communities involves finding beneficial uses for stormwater and reuse water, which are increasingly valuable resources.
Winter Haven is situated at the headwaters of the surface water and groundwater systems that comprise the Peace River Basin. From its beginning in Winter Haven, Peace Creek flows into the Peace River, which extends south to Charlotte Harbor and the Gulf of Mexico. Because of its location in the Peace Creek watershed, in the upper reaches of the Peace River Basin, Winter Haven must capture, store, and use water before it leaves the watershed. As with many other communities, however, Winter Haven’s ability to do so has been compromised in the name of providing flood protection for a small part of the community, without consideration of the need to protect water resources for people and natural systems over the long term.
To remedy this problem, Winter Haven is developing a conceptual plan to preserve and protect its surface water and groundwater resources for human and environmental use. The backbone of the plan is an interconnected hydrologic network of lakes, canals, wetlands, aquifers, open spaces, and parks. This network will reconnect portions of the hydrologic system to mimic the historical movement and storage of water and meet the long-term water resource needs of the entire community, including supply (water quantity), treatment (water quality), flood protection, and preservation of natural resources.
 |
Photo: Mike Britt
A group of Ibis caught flying into the park during a foggy late winter morning |
The conceptual plan is a cornerstone of the city’s “Go Green Winter Haven” initiative to work toward a sustainable “green” city and enhance the quality of life of current and future generations. It represents the city’s commitment to its citizens to provide a desirable, enjoyable, beautiful, and safe place to live.
This article discusses the predevelopment and post-development hydrology of the Peace Creek watershed and Winter Haven and the specific actions recommended in the conceptual plan to restore the movement and storage of water. The plan is one of dozens of planning efforts in the Peace River Basin and Peace Creek watershed; PBS&J has been the consultant for most of these projects. The company’s prior experience in the region has greatly facilitated integrating the technical and scientific information on which the basic elements of the conceptual plan are based.
Benefits of the Conceptual Plan
The plan is an investment in the city’s natural infrastructure as opposed to engineered infrastructure. It preserves and enhances the innate ability of the watershed’s unique landscape to provide multiple water resource benefits, such as improved water quality, water supply, natural systems, and flood protection. In the long term, using the natural infrastructure to provide these benefits will result in a less costly, more efficient water storage and delivery system for all future uses. Other benefits include a strengthened local economy; greater social, cultural, and recreational opportunities; and a more aesthetically beautiful city. Together, all of these enhance the community’s overall quality of life.
The Predevelopment Peace Creek Watershed
Across Florida, the natural predevelopment landscape efficiently retained both surface water (lakes, rivers, and streams) and groundwater (aquifers), slowing the flow of water through the landscape. Figure 1 shows a typical natural landscape in Florida, which is similar to the landscapes of many states. In the headwaters of the system, lakes and isolated wetlands provide water-quality treatment and infiltration into the aquifer. In some places, the aquifer literally seeps out of the landscape through wetlands, creating ephemeral streams that form disconnected strands and sloughs in the middle reaches of the watershed. These wetlands, along with the broad floodplain forests in the lower reaches, facilitate critical surface water storage and conveyance during large storm events.
The movement of surface water and groundwater in the Peace Creek watershed is similarly organized. In the headwaters where the elevation is highest (see the area outlined in red at top left in Figure 2), ancient sand dune deposits contain sandy sediments that can infiltrate rainfall at very high rates. Over time, rainwater dissolved portions of the underlying limestone, the surface subsided, and numerous lakes formed within the ridge from groundwater seepage. These lakes are well connected to the surficial and deeper Floridan aquifers, rising and falling with aquifer levels. There are very few, if any, surface streams, indicating that rainwater did not run off the surface of the ground. Instead, it infiltrated into the ground and then slowly moved through the surficial aquifer to recharge the area’s many lakes and eventually the Floridan aquifer, which is currently the sole source of drinking water for the city of Winter Haven.
In the middle reaches of the Peace Creek watershed, groundwater that collected under the ridge flowed out to form seepage lakes and wetlands. During heavy rains, these lakes overflowed their banks, and the water moved across the landscape through elongated strands or sloughs and wetland areas.
Much like the Everglades in south Florida, the lower portion of the Peace Creek watershed historically contained a wetland slough and broad floodplain that spread the water over a wide area and retained it in the landscape before the water flowed into the Peace River. During periods of low rain, there was little flow in the system. However, during periods of heavy rainfall, the excess water was dispersed quickly across a large surface area. In the lower reaches, where Peace Creek flows into the Peace River, sloughs likely connected to form forested swamp floodplains with numerous braided channels.
 |
Photo: Mike Britt
The flock of Ibis photographed after they landed |
Thus the watershed effectively held water both above and below the land surface. The water stored in the surficial and Floridan aquifers in the upper part of the watershed maintained lake levels during periods of low rainfall, when evapotranspiration increased water demand. Similarly, in the middle and lower portions of the watershed, wetlands stored water, slowing down the rate at which water flowed to the Peace River and maintaining flows during dry seasons.
The Post-Development Peace Creek Watershed
In many watersheds nationwide, a significant loss of hydrologic function often accompanies development. The movement and storage of water are altered for human uses such as agriculture, homes, schools, businesses, industry, and roads. Across the country, development often occurs first in the highest, driest areas with the greatest potential for aquifer recharge. The last areas to be developed are usually those that were historically wet; often these areas are still prone to flooding.
The post-development Peace Creek watershed is no exception. The higher, drier areas in the upper portion of the watershed were the first to be developed for homes and businesses. This high-recharge area historically helped maintain water levels and water quality in the lakes and also helped to recharge the Floridan aquifer. Stormwater “improvements” associated with the resulting development took the rainwater that once moved underground into the surficial aquifer and instead directed it into the lakes. Regional agricultural and urban withdrawals lowered Floridan aquifer levels. The resulting loss of storage and flow has lowered lake levels and diminished water quality.
In the early 1900s, many canals were constructed in the watershed (Figure 3). For example, the Peace Creek Drainage Canal was constructed to drain the northern Chain of Lakes, the Wahneta Farms Canal drained the southern Chain, and numerous other canals were built to connect Winter Haven’s lakes and make them navigable. As a result, water was rapidly moved out of the watershed, and levels in a number of the lakes and the surrounding aquifer have dropped by approximately 10 feet during the last 90 years. Algal blooms now occur in a few of the lakes during the drier, warmer spring months, and some of the canals go dry during drought years.
New development, especially in the southern third of the watershed, will likely result in further dewatering of the watershed if development is allowed to occur as in the past. Future projects include a proposed new transportation hub for shipping goods using rail and overland truck, development of new commercial and industrial corridors along several major highways to support the hub, and construction of a new parkway within the next 10 years. Within the next 20 years, the city and the Peace Creek watershed may be virtually built out.
Opportunities for Restoring the Historical Movement and Storage of Water
In any community, a detailed understanding of the movement and storage of water provides a sound foundation for water resource management and restoration activities. Through the comprehensive assessment carried out during the development of the conceptual plan, the city of Winter Haven has gained a much better understanding of the hydrologic function that has been lost through human alterations. The goal of the plan is to restore as much of the historical storage and movement of water through the watershed as possible, using stormwater and reuse water as a resource, while still providing adequate flood protection. This effectively balances the water needs of both people and natural systems.
The principal opportunities for restoring the watershed’s hydrologic function are as follows:
Treatment and infiltration. The most important opportunity in the Winter Haven residential and commercial area, situated in the upper reaches of the watershed, is to restore infiltration of stormwater to recharge the surficial aquifer. This will provide storage capacity and flow for the lakes during dry seasons. Associated with this opportunity is the need to ensure that stormwater receives adequate treatment on the surface before infiltrating to the aquifer or entering any of the lakes.
Storage and conveyance. The most important opportunity in the middle and lower reaches, which are the areas with the highest development pressure today, is to provide for additional storage of water and wider conveyance paths through the system. Increasing the amount of available storage will allow more water to be retained in the lakes in the upper part of the watershed during years with a water surplus. During storms, excess water will flow into the middle reaches, where it will be stored in the landscape (wetlands). Increased storage on the land results in higher surficial aquifer levels, which will provide more consistent outflows to Peace Creek during dry seasons. Finally, in the lower portion of the watershed, a wider conveyance area will allow large volumes of water to move through the system more quickly with less damage to property during flood events. At the same time, protecting this low-lying conveyance area from future development will help to protect property from flood damage.
Figure 4 shows the reconnected hydrologic network. In the upper portion of the watershed, a number of features provide treatment and infiltration in the downtown and residential areas. Figure 5 contains an aerial view of downtown Winter Haven, with the potential areas for treatment and infiltration highlighted in green. However, these features are more difficult to discern at this scale and are described in detail in a later section.
Figure 4 shows an interconnected series of wetlands that provide storage and conveyance in the lower and middle portions of the watershed, generally in the area near the Peace Creek Canal.
Increasing Treatment and Infiltration in the Upper Peace Creek Watershed
To provide for infiltration of stormwater runoff in the upper reaches of the Peace Creek watershed, open land is needed in an already highly developed landscape. An initial goal is to devote 5% of the current land area to implementing stormwater infiltration technologies. This percentage is based on the calculation that about 2 billion gallons a year of stormwater are lost to infiltration because of altered hydrologic function, and 5% of the watershed’s land area would be needed to infiltrate that quantity of water annually.
By providing depressions in the landscape to collect runoff before it enters storm drains, most of the runoff can be captured and infiltrated into the surficial aquifer. The best strategy is to develop as many small depressions as possible, spread throughout the landscape, to mimic infiltration patterns in the natural system as closely as possible.
Different strategies would be required for the various land use types in the watershed. In short, different opportunities lend themselves to the city’s residential areas, the downtown commercial area, and the edge where development is ongoing.
Opportunities in Residential Areas
Significant quantities of water can be captured in the following ways.
Capturing water that runs off the roofs of private homes. Private rain gardens in homeowners’ yards can be incorporated into landscaping and located anywhere where a depression can be created.
Capturing water that runs off streets and driveways. Water can be collected in long, vegetated swales that parallel the road. These swales can be located in a median if present, or within the public right of way along a road.
 |
Photo: Mike Britt
Foot bridge on the lakefront portion of the park linking the gravel parking area to the island that eventually leads to the boardwalk out to Lake Howard |
Using portions of neighborhood parks. Parks can be used for larger retention areas that may fill only during heavier rains. There are two different types of these stormwater parks, or hydric parks. Some contain water all the time, and others fill with water only during heavy storms. The former could be used to enhance water storage in areas where there are existing natural features, such as groundwater seeps. The latter would remain dry most of the time and would be available for recreation once the stormwater infiltrated.
Winter Haven has already implemented two such nature park projects in urban settings to receive stormwater from drainage areas covering 753 acres. A third park, still in the planning stages, will receive stormwater from a 328-acre area. This integration of stormwater treatment and storage areas into the fabric of the community as a recreational and aesthetic amenity is a central element of the conceptual plan. Heavily used by residents and visitors, the parks are pleasant places to spend time in, because of the combination of water, natural systems, and wildlife found in the midst of an intensely developed urban area.
Opportunities in the Downtown Commercial Area
Commercial areas can be one of the most challenging places to capture stormwater because of the high percentage of impervious surface and lack of available land. Besides roofs and roads, parking lots make up a large portion of the surface area. Three principal ways exist to capture stormwater in commercial areas.
Constructing swales within and along the edges of parking lots. This is one of the best ways to capture stormwater. Some parking spaces could be lost to provide enough area for infiltrating runoff.
Constructing roadside swales in the city’s commercial district to capture runoff from street surfaces. Swales are particularly important along the edges of waterbodies to help provide some treatment before stormwater enters them.
Retrofitting parks and open spaces with shallow depressions to collect runoff. Because so much of Winter Haven’s commercial district is paved over, more of these depressional areas will be needed to capture stormwater than is needed in residential landscapes. The city has a central park that provides a large, open space in the urban center, affording opportunities for retrofitting.
Figure 6 shows stormwater capture technologies implemented in the landscape. Roadside and parking lot swales (at top) are implemented on the edges of paved areas. These features can be constructed with curb breaks to allow water to enter, as in the parking lot swale, or without any curbs, as illustrated in the roadside swale.
Rain gardens (at bottom center and bottom right) can be implemented right at the downspout areas of buildings or out in the yards as part of the landscaping. With careful design, they can be both low maintenance and aesthetically pleasing.
Finally, pocket wetlands (at bottom left) can be created to hold water for longer periods. These create variety in the landscape and help provide better stormwater treatment, because the living organisms that flourish in such systems work to break down contaminants. If these areas are already present, they provide a natural fit. Places in the downtown area where groundwater historically seeped to the surface would be ideal locations for creating such features.
Opportunities at the City’s Edge
Some of the greatest opportunities to maximize treatment and infiltration lie at the edges of cities, where development has not yet occurred or is still occurring. Planning, design, and permitting should focus on preserving natural hydrologic function and as many existing natural features as possible.
The conceptual plan contains the following five major recommendations for developing undeveloped areas at the outer edges of Winter Haven.
Preserve pre-existing, low-lying areas as spots that collect and infiltrate rainwater. Don’t fill in these locations, but allow them to continue their important function in the landscape.
Enhance and extend the wetland edges of lakes with hydric parks. These areas can be used to store stormwater and
provide treatment before the water enters the lakes, helping to improve water quality. They also become recreational attractions and preserve the beauty of the landscape. As discussed earlier, the city has already created two of these parks, with the third in the planning stages.
Preserve wet corridors in the landscape. During heavy rainfall, the corridors provide a path for the water to move across the landscape without affecting permanent structures. These areas also increase the amount of water storage, helping to maintain higher water levels in the surficial aquifer and the lakes during normal weather patterns and helping to replenish the lakes during dry periods. The corridors can be enhanced to create wetland areas that provide opportunities for recreation and allow wildlife to move freely.
Increase the amount of available storage to allow more water to be retained in lakes in the upper part of the watershed during years with a water surplus. In the event of a storm, excess water will flow into the middle reaches, where it will be stored in the landscape (wetlands). Increased storage on the land results in higher surficial aquifer levels, which will replenish the lakes and provide more consistent outflows to Peace Creek during dry seasons. Finally, in the lower portion of the watershed, a wider conveyance area will allow large volumes of water to move through the system more quickly with less damage to property during flood events. At the same time, protecting this low-lying conveyance area from future development will help to protect people’s assets from flood damage.
Require development to comply with permit requirements specifying the use of low-impact development standards. Requiring a new development to manage all its runoff within the development itself ensures that it is not exacerbating a problem that will require more land elsewhere to solve.
Increasing Water Storage and Conveyance in the Middle and Lower Peace Creek Watershed
Ninety percent of storm events in Florida generate less than an inch of runoff. This water should be retained on the landscape and allowed to infiltrate. However, in a system such as Peace Creek, it is conveyed off the land as stormwater. With more than an inch of rainfall, only the excess should be discharged. For peak events, all of the water can be passed through the system and discharged, but only when absolutely necessary to prevent flooding.
Increased water storage can be provided by creating wetland storage areas, stormwater treatment areas, and forested wetland sloughs to help buffer the system against droughts while at the same time providing flood protection. This can be done by designing a system with significant surface water storage along the current Peace Creek Canal, and a wider conveyance corridor that facilitates high-volume flows during flood events, as shown in Figure 7 in the multiple cross-section views of the restored canal.
Wetland Storage Areas
In the restored system, the Peace Creek Canal would be removed and water would be allowed to spread out across the landscape. This change would slow down the water moving through the system. The water would be stored for a much longer time, allowing it to recharge the surficial aquifer.
The newly created wetland storage areas would increase the baseflow provided to Peace Creek during the driest times of the year, when water is most needed in the system. It would also dampen peak flows during high rainfall, contributing to flood protection downstream.
Wetland storage areas should be designed with varying water depths that provide a wide range of wetland habitat and support diverse plant and animal life. Higher-elevation land areas with shallow water should be provided to support forested wetlands and emergent wetland marshes. Medium-depth pools provide for submerged vegetation. Deep open-water pools provide refuges for wildlife when the system experiences dry cycles and most of the wetland dries out. The variation in water depth and hydroperiod will create a system that contains all the biotic components necessary to adapt to changing conditions in the future with low management requirements.
Stormwater Treatment Areas
Stormwater treatment areas are designed to hold water for three days or longer to provide water-quality treatment. The extended retention time allows biological and chemical processes to remove nutrients such as nitrogen and phosphorus, as well as other pollutants, from the water column and sediments. In the restored system, these areas would treat contaminated water as it flowed off developed and agricultural lands. The large amount of surface area would efficiently treat normal amounts of rainfall, significantly improving water quality in the system.
Forested Wetland Sloughs
The surface storage sites should be connected by corridors that convey flow when there is excess water in the system. During flooding, large volumes of water need to move quickly through the system. However, the corridors should help to minimize flow through the system during dry seasons, when water conservation is important.
In contrast, the current conveyance system, which consists of canal channels cut into the ground, is designed to carry surface water and groundwater out of the watershed continuously. To ensure high flows during storms, the canals are kept clear of any obstacle to flow. Although this approach works well to move water out of the system, in dry seasons water from the surficial aquifer enters the canal and continues to flow after stormwater has abated, continually leaching from underground supplies.
To restore the system, the canal should be dechannelized, and a wider wetland slough should be created. The conveyance capacity in the restored system would be at least equal to or greater than that of the existing system, including an allowance for friction loss. The revised capacity would be validated through modeling. Using this approach, the slough will at least maintain, if not enhance, the level of service for flood protection. For example, if a canal is 30 feet wide and 10 feet deep, it has 300 square feet of flow area. A wetland 3 feet deep and 100 feet wide provides the same area for flow (with some additional width provided for friction loss), and creates more benefits for the watershed in the form of habitat, increased water storage, aquifer recharge, and recreational and aesthetic amenities.
During periods of low flow, water will travel slowly through the slough in small, braided streams. These numerous small stream channels create friction, helping to slow the water as it moves through the system. During high flows, these streams will overflow their banks and use the whole slough area to accommodate the flow. The wider corridor will allow the same volume of water to flow through the system as the channel. Once the storm surge has passed, the water will retreat to the small streambeds, where flow will be minimized, reducing the speed with which it leaves the watershed.
These sloughs can be allowed to grow as forested wetlands with a tree canopy overhead. Able to tolerate the system’s constant variation in water levels, the wetland trees shade out vegetation that might impede higher flows and keep the stream beds clear with minimal maintenance.
Implementation and Funding
The city of Winter Haven is committed to implementing the conceptual plan. The city has already completed several stormwater parks and is working on several other projects. By allowing some development where it might not otherwise occur, and mitigating those impacts elsewhere, the city is also providing an incentive for private developers to incorporate elements of the conceptual plan, such as portions of the flow-way, into their projects. The various elements of the plan will be implemented incrementally as funding becomes available.
A large percentage of the funds for implementation may come from the creation of a mitigation bank in the area where much of the restoration work would be carried out. The sale of mitigation credits in this restoration area would help to fund the restoration. Whether developed privately or by the city, the mitigation bank would accomplish the same objective of constructing some of the plan’s elements.
Winter Haven is cooperating with the Southwest Florida Water Management District, which supports the plan and will participate in funding some of the planning and design. In particular, the district will evaluate the impacts of the plan on current levels of service to ensure that flood protection is not compromised. Continuing the partnership with the district and with the development community that is already under way is essential to meeting larger, long-term community water resource needs.
Conclusions
Integrated water resource management is the key to meeting the current and long-term water resource needs of communities across the country, including Winter Haven. A departure from the current piecemeal way of managing water resources, this integrated approach looks at the watershed’s hydrologic network as a whole, develops a detailed understanding of the loss of hydrologic function that has occurred, and reconnects portions of the network to mimic the historical movement and storage of water. It preserves and enhances the watershed’s capacity to provide multiple water resource benefits, including supply (water quantity), treatment (water quality), flood protection, and preservation of natural resources. In contrast, engineered infrastructure is much more costly and much less efficient in storing and delivering water for future use.
The conceptual plan for the upper, middle, and lower reaches of the Peace Creek watershed forms a comprehensive approach to managing stormwater. Instead of stormwater being moved out of the watershed as quickly as possible, it is captured and stored both below and above the ground, in aquifers, lakes, canals, wetlands, open spaces, and parks. This helps to ensure the health of the region’s lakes by providing higher water levels throughout the year, and also conserves water in the system so it is available during dry seasons. It is the key to protecting the lakes, improving water quality, enhancing water supply, maintaining natural systems, and providing flood protection. The restored natural systems provide many additional benefits, including recreational, aesthetic, and waterfront amenities; a more livable, enjoyable, and safe community with increased property values; strengthened community identity; and improved community quality of life.