Natural Resources Protection in the Upper Sugar River Watershed Michael Kakuska, CARPC

Transcription

1 Natural Resources Protection in the Upper Sugar River Watershed Michael Kakuska, CARPC Water is a significant resource in Dane County, contributing tremendously to the region s environmental and economic well-being -- as well as the quality of our everyday lives. The quality of our ground and surface waters has much to do with the reason people live, visit, and move here. Dane County is the second-largest metropolitan area and one of the fastestgrowing counties in the state. However, this growth and development does not come without its share of problems. The quality of the lakes, streams, and groundwater supplies, and the biologic and economic systems they support will deteriorate unless measures are taken to address the impacts of our activities. 1

2 Our water resources are the lifeblood of the region The basic structural element of natural resources protection is the Watershed A Watershed is defined as area contributing water to a specific body of water It is often compared to a topographic bathtub, bowl, or basin separated from neighboring watersheds by ridgelines Watersheds are scalable Like nested Russian Dolls they flow into successively larger versions of themselves While similar in terms of form and function, for clarification purposes watersheds are often given more descriptive names, depending on the scale For example, a particular catchment area for a neighborhood in Verona may drain to the larger Badger Mill Cr. Subwatershed, which drains to the larger Sugar R. watershed, which drains to the Sugar-Pecatonica Basin, which drains to the Mississippi R., and ultimately the Gulf of Mexico Land use defines character and quality of the resource 2

3 The Sugar R. is designated an Exceptional Resource Water (ERW) ERWs are surface waters which provide - outstanding recreational opportunities, - valuable fisheries and wildlife habitat, - good water quality, and - they are not significantly impacted by human activities. ERWs warrant additional protection from pollution Both the Sugar R. and Badger Mill Cr. are classified as Class II trout streams Class II trout streams have good survival of adult trout and some natural reproduction The Sugar R. is an important resource in the region because of its Exceptional Resource status, as well as other outdoor recreational and educational activities including the Military Ridge State Trail, Ice Age Trail, many valuable wetlands along the Sugar R., and a water-based canoe trail from Sugar River Rd. to Paoli, and Lake Belle View. 3

4 Land use in the watershed defines the character and quality of the resource Researchers have shown a clear disproportional or opposite relationship between increasing levels of development and reductions in water quality As development increases (represented by connected imperviousness, or left to right on the X-axis) water quality declines (represented by the types of fish, or top to bottom on the Y-axis) zero being low levels of development and water quality, respectively Notice that there s significant decline or threshold in water quality that results from surprisingly low levels of development --- between around 5-10% This is unmitigated development in other words no protection measures Development and management strategies that protect areas along the shoreline, and minimize the effects of imperviousness, can help prevent this damage 4

5 One strategy is to reduce Impervious Cover or, alternatively, maximize natural vegetation -- especially along the shoreline. Natural vegetation provides food and cover for the full spectrum of wildlife,with water as the basic common ingredient This land-water edge is highly productive from a biological point of view. If you develop down to the shoreline, you lose all that and more This sets off a domino effect that ripples through the environment 5

6 Another promising strategy is to mimic pre-development hydrology -- such as through infiltration practices. As communities develop, the ground/surface water balance shifts from a groundwater-dominated system to a surface water-dominated system For example, for natural conditions (upper left), Infiltration accounts for approx. 50% annual precipitation with 10% runoff For highly developed areas (lower right) this situation is reversed; Infiltration accounts for approx. 15% with 55% runoff, picking up pollutants from streets, roads, and parking lots along the way Maximizing infiltration through storm water controls, gets water back into the ground, thereby reducing erosion, sedimentation, O&G, toxics, and other pollutants washing into our wetlands, lakes, streams Let s look at these two strategies more closely: 1) Minimizing impervious cover and maximizing natural vegetation, and 2) Restoring or mimicking predevelopment hydrology 6

7 These are the more Critical Natural Resources (see legend) This is a complex system of interacting parts This assumes development up to the waters edge which we know becomes a problem 90% of all living things found in our lakes and streams are found along the shallow margins and shores, so it s probably best that we focus our attention here. 7

8 The literature on buffers for habitat protection makes it clear that there is no magic number that will automatically guarantee a certain level of protection It all depends on your resource objective -- what you are trying to accomplish. This chart demonstrates the ideal buffer range for a desired objective, such as storm-water run-off control Based on comprehensive surveys of the scientific literature, buffers should be a minimum 100 feet in width to provide nutrient, sediment, and pollutant removal, and moderate temperature change. Beyond 100 feet you begin seeing diminishing returns in for water quality protection objectives alone. Over 300 feet is needed to provide wildlife habitat. Most natural resources objectives can be accomplished within a buffer area of 300 feet, and should also include the floodplain where it exists for flood protection. As buffer width increases, wildlife benefits also increase. 8

9 Ecological pyramids of numbers, biomass, and energy for a forest, a shallow pond, and an "old field. " These are ecological pyramids representing numbers of organisms, biomass, and energy flow for forests, shallow ponds, old fields -- typical, natural areas Starting with the plants and animals at the base, and building up to top level carnivores or pinnacle being ourselves, human beings While we ve come a long way from the hunting/gathering society of our ancestors, thus it s our responsibility to maintain these ecological processes, where we can, and avoid destroying them, if we can possibly help it. It s really a matter of avoiding these sensitive areas and directing our development activities where they are more suitable. By protecting the environment and the numbers of organisms, a broader base and healthier, more robust system can exist. Alternatively, cutting too deeply into the base of the pyramid, the remaining system becomes reduced, unstable, and can collapse 9

10 So, how can we approach this? Scientists have come up with the concept of an umbrella species. By protecting Umbrella Species you also protect less sensitive species that depend on the same habitat. A canary in a coal mine is a good example as it relates to human beings. It turns out amphibians are good umbrella species for biological communities being solidly in the middle of the ecological pyramid. Amphibians depend on both terrestrial and aquatic environments to complete their life cycles. By protecting them, you protect the food source upon which they feed, as well as they themselves as food for higher level animals Scientists have actually tagged these little guys and determined their traveling distance, or so-called Core Habitat necessary to complete their life cycles 10

11 Zones of Protection for Wetlands Core Wetland Aquatic Buffer ft Core Habitat ft 150 ft Terrestrial Buffer Using these concepts they suggest three protective zones: 1. Starting from the wetland edge, an Aquatic Buffer Zone (between ft) should be established to protect water quality 2. A second zone (between 500 and 1000 ft, overlapping the first) would encompass the core habitat -- defined by the Umbrella Species, depending on the min. or max. being used 3. A third zone, Terrestrial Buffer would buffer the core habitat from surrounding land uses (150 ft) There we have it: a minimum 500 ft Core Habitat, which includes an Aquatic Buffer, plus a Terrestrial Buffer for a total 700 ft Riparian Corridor primarily along wetlands We ll get back to this in a minute 11

12 In addition, scientists recommend wildlife corridors to help reverse habitat fragmentation and patch isolation from our development and agricultural activities In general, most natural resource objectives can be accomplished with a corridor width of 300 feet from the edge of a stream and 700 feet from the edge of a wetland or small drainage pond. So, how could buffers be incorporated into the planning process? I think it s best to identify these sensitive natural resources up front get out ahead of development. We re kicking around some of the same ideas for directing FUDA plans for communities. How might this look for Verona? 12

13 Well, if you scale back a little, squint your eyes, it s actually pretty clear It certainly needs to be based on wetlands (regulated anyway) Green areas Add a Core Habitat Area for umbrella species Yellow border And a buffer area to protect it from adjacent land use activities Red margin You can see a clear pattern emerging Add wildlife corridors connecting these areas along streams and the basis for a Riparian Corridor system for urbanizing areas emerges. Basically following the drainage pattern connecting across jurisdictional boundaries Not too surprising since water is the lifeblood of the region Our natural resources should be the principle element of design -- Not an inconvenient afterthought You can pretty much ignore what s already been developed and focus on what s left the white areas Now we can debate all day long whether the corridor should be 3, 5 or 700 feet The important point is that we avoid these areas Move development out of the lowland areas 13

14 What does this look like at the county scale? Using Extraterritorial Jurisdiction boundary (ETJ) as the Potential Development area, there appears to be plenty of room for communities to grow the white areas Focusing their growth either N, S, E, or W allows considerable flexibility We need to direct development away from these critical colored areas and focus it into areas more suitable for it. Realize the focus for this is on Urban Service Areas largely within the ETJ zones This would not effect lands remaining unincorporated or undeveloped They are already largely protected from development by agriculture Development and nature can co-exist We just need to give it a little breathing room Develop up and avoid lowland areas Thereby providing greater infiltration, groundwater recharge, buffering capacity, trail corridors, wildlife habitat, and other quality of life amenities that make this area so unique 14

15 There are also important stormwater considerations. With the increased urban growth in the area, there is the potential that these valuable resources could be forever degraded and even lost. When an urban area is developed, natural drainage patterns are changed. This shows typical pre-development and post-development hydrographs for a watershed that is developed for urban land uses. Post-development results in: - Higher and more rapid peaks (flashier flows) dotted lines - More runoff volumes - Lower baseflows compared to pre-development conditions (the solid line) where everything is naturally more gradual or subdued 15

16 Source: Ken Potter, UW-Madison Two familiar local examples are Garfoot Creek (a rural, coldwater stream) and Spring Harbor Storm Sewer (an urban tributary to Lake Mendota). While stormwater ordinances usually focus on preventing stormwater peaks, they typically do not address increasing volumes of runoff. 16

17 An emerging concept in water resources management is to require that development have minimal hydrologic or water quantity impacts Up until relatively recently the emphasis has been largely focused on water quality. However, research has actually shown that by the time the water quality problems become evident, the damage has already largely been done by changes in water quantity - that is, greater frequencies and durations of stormflows. 17

18 The typical control is to flatten the peaks using engineered structures to limit post-development peak flows to pre-development conditions The area below the hydrographs represents the volume of additional runoff (gray) resulting from doing this Note, however, that by flattening the peaks you draw the volume out This results in more frequent and longer durations of higher flow thru the storm profile Greater frequencies and durations of higher flows result in more force applied streambeds and banks for longer periods of time 18

19 This results in greater scour, channel widening and incision, bank erosion, sedimentation of pools and gravel spawning beds, clogged gills in fish and aquatic insects, lower baseflows, higher temperatures, increased flooding, etc. This is in addition to water quality impacts from runoff alone This is the typical response of stream channels to increased levels of urbanization This is a lot of material being washed downstream which does considerable harm 19

20 Hydrologic impacts of urbanization on streams: More bankfull or higher stream volumes More frequent and higher floods Higher peaks and flashier stormflow for a given size storm Longer duration of higher streamflows Less groundwater recharge, therefore lower dry-weather baseflow levels, higher temperatures Greater water table and wetland water level fluctuations The hydrologic impacts of watershed urbanization on streams are well established: More bankfull or higher stream volumes More frequent and higher floods Higher peaks and flashier stormflow for a given size storm Longer duration of higher streamflows Less groundwater recharge, therefore lower dry-weather baseflow levels, higher temps. Greater water table and wetland water level fluctuations 20

21 All these physical, chemical, and biological alterations result in decreased water quality As seen previously, relatively small amounts of urban land use in a watershed can lead to major changes in the biotic community And there appears to be a threshold of urbanization beyond which degredation is rapid and dramatic We can do more to prevent this damage In Conclusion I hope these points will be useful in your exercise today Two Main Points: 1) Minimize Impervious Cover and maximize natural vegetation especially along our sensitive water resources 2) Try and mimic or maintain natural hydrologic conditions such as through infiltration and aggressive stormwater controls 21

22 Questions? Questions? 22