2011 State of the Inland Bays

Embed or link this publication

Popular Pages

p. 1

the delaware center for the inland bays tate of the bays 2011 state of the delaware inland bays


p. 2

the inland bays watershed quick facts · hewatershedoftheinlandbaysis292squaremiles t oflandthatdrainsto35squaremilesofbaysandtidal tributaries.locatedwithinsussexcounty,delawareon themid-atlanticcoastalplainoftheunitedstates · ehobothbayandindianriverbayaretidallyconnected r totheatlanticoceanbytheindianriverinlet.little assawomanbayisconnectedbytheoceancityinlet 10milestothesouthinmaryland · hebaysareshallow,generallylessthan7feet,andhave t anaveragetidalrangeof3feet by christopher bason deputy director the delaware center for the inland bays on behalf of the scientific and technical advisory committee of the delaware center for the inland bays dr william ullman chair this report may be found at www.inlandbays.org cover photo young osprey on nest on rehoboth bay by dennis bartow 2 2 september 23 2011


p. 3

watershed condition the state of the inland bays and their restoration the inland bays are coastal lagoons bays that lie behind a narrow barrier island that separates them from the atlantic ocean travelling down route 1 through dewey beach bethany beach and fenwick the inland bays lay to the west they are unique places where `the rivers meet the sea where freshwater flowing from the land and down tributaries mixes with seawater that flows through inlets carved into barrier islands a collage of saltmarshes tidal flats bay grass meadows oyster reefs and winding saltwater creeks make up this environment for thousands of years the bays have supported an abundance of fish and birds that come here to feed reproduce and grow the beauty and productivity of this estuary now supports a thriving human culture and economy the bays are dynamic constantly changing in response to human activities and the climate fifty years ago the bays were thought to be generally healthy clear waters with plentiful bay grass meadows productive oyster reefs and oxygen levels that supported diverse and plentiful fish populations but years of accumulated nutrient pollution and habitat loss have changed the bays to generally murky waters that are dominated by algae have very few bay grasses or oysters and do not support healthy oxygen levels in many areas habitat restoration and major pollution reductions are needed to restore water quality and achieve a healthy estuary once again since the adoption of the 1995 inland bays comprehensive conservation and management plan much progress has occurred toward these goals nutrient loads management water quality living resources now some environmental indicatorssuggestthat accomplishmentsmadeunder theplanarebearingfruitand maybemovingthebaysbackin ahealthydirection pathogens contaminants climate 3


p. 4

assessing the state of the bays to assess the health of the inland bays we selected a suite of environmental indicators specific species and conditions that are measured over time to determine how the bays are changing and how much progress has been made toward restoration goals thirty-one individual environmental indicators are grouped by subject matter and presented as the six chapters of the state of the bays report each group is assigned a status and a trend by assessing its indicators together · the indicators are based on measurements of environmental parameters and management actions · status and trends are assigned using best professional judgment to more completely document bay health a number of new indicators were added since the last environmental indicators report published in 2004 a status bar common to state of the bay reports from other national estuary programs was also adopted horseshoe crabs spawning on indian river bay 4


p. 5

watershed condition table of contents the state of the inland bays and their restoration 3 assessing the state of the bays 4 watershed condition 6­15 human population growth 8 land use 9­10 impervious surfaces 11 water quality buffers on croplands 12 natural habitat protection and restoration 13­14 indian river inlet flushing 15 nutrient loads and management 16­25 loads of nutrients from point sources 18 loads of nutrients from non-point sources 19­20 loads of nutrients from the atmosphere 21 nutrient management practices 22­23 septic system conversion to central sewer 24 water quality 26­35 dissolved nitrogen and phosphorus concentrations 28 algae concentration 29 water clarity 30 water quality index 31 seaweed abundance 32 bay grasses 33 dissolved oxygen concentration 34­35 living resources 36­49 eagles ospreys 38 winter waterfowl 39­40 hard clam landings 41 oysters 42 blue crab abundance 43 fish abundance 44­45 recreational fishing 46­47 number of fish kills 48­49 pathogens and contaminants 50­55 fish consumption advisories 52 recreational water quality 53 approved shellfish growing waters 54­55 climate 56­59 carbon dioxide concentration and air temperature 58 sea-level rise 59 state of the bays summary 60­61 references 62­63 acknowledgements back cover nutrient loads management water quality living resources pathogens contaminants everything that happens on the land of the watershed affects the bays buzz henifin climate 5 5


p. 6

watershed condition 1 watershed condition 6 6


p. 7

watershed condition overview watershed condition at 10 impervious surface coverage on a watershed itiswidelycitedthatadecreaseinwaterqualitybegins therehobothandlittleassawomanbaywatersheds havenowcrossedthat10%threshold the human population of the watershed continues to increase and with it rapid changes in land use primarily the conversion of forests croplands and wetlands to developments development increases the acreage of impervious surfaces such as roads roofs parking lots places where precipitation can t seep into the soils and be filtered rain water becomes stormwater runoff as it travels across these surfaces picking up pollutants and carrying them to waterways at 10 impervious surface coverage on a watershed it is widely cited that a decrease in water quality begins the rehoboth and little assawoman bay watersheds have crossed that 10 threshold much of the new development is concentrated around waterways where it impacts bay shorelines forested buffers between croplands and streams also decreased in width from 1992 to 2007 looking ahead the increasing amount of human activity in the watershed will continue to challenge our efforts to protect and restore the bays mitt buzz henifin former citizen s advisory comnd ee fenwick isla chair inspects storm drain in nutrient loads management water quality living resources watershed condition status bar pathogens contaminants negative positive how to read the status bar status is indicated by a dot on the status bar the farther to the left of the center the dot is the more negative is the status of the group of indicators the farther to the right of the center the dot is the more positive the status if the dot is in the center the status is fair a trend arrow pointing to the left indicates a negative trend a trend arrow pointing to the right indicates a positive trend no trend arrow indicates a neutral or unknown trend impervious surfaces in dewey beach climate 7 7


p. 8

human population growth theyear-roundandseasonalpopulationsofthe watershedareprojectedtocontinueincreasing.sussex countyiszonedtoeventuallyholdapopulationof over2millionresidents from 1990 to 2010 the year-round watershed population is projected to have doubled currently 196,201 year round residents live in sussex county with 87,210 or 44 residing in the inland bays watershed as the number of people in our watershed increases we consume more resources and generate more waste the success of environmental management in the inland bays watershed is dependent on how we plan for population growth and its impacts although the watershed is a premier tourist destination and hosts hundreds of thousands of visitors each summer its seasonal and visitor population is not directly counted a method of estimating seasonal and visitor population by measuring flows to wastewater treatment plants found that the monthly seasonal and visitor population of the watershed ranged from 41 to 200 of the year-round resident population at the peak of the tourist season in july the estimated total population of the watershed swells to 252,000 people concentrated around the bays resident population of sussex county and the inland bays watershed over time dashed lines indicate projections 300,000 250,000 200,000 150,000 100,000 resident population pulation sussex county watershed 50,000 0 looking ahead the year-round and seasonal populations of the watershed are projected to continue increasing sussex county is zoned to eventually hold a population of over 2 million residents 8


p. 9

land use watershed condition from1992to2007theinlandbayswatershedlost overafootballfieldofforestlandseveryday in 2007 agriculture was the largest use of land 32 followed by developed/developing lands 22 forested lands 17 and then wetlands and waters 16 and 12 the health of the bays depends on how the land of the watershed is used since various land uses result in different types and amounts of pollutants entering waterways for example a dense residential development constructed without stormwater management facilities can contribute four times as much nitrogen to the waters than a forest of the same size heavy metal contaminants and bacteria loads to waters also would be relatively higher the success of nutrient and stormwater management is greatly dependent on land use and land management from 1992 to 2007 the land use of the watershed changed significantly developed lands increased by 25.8 square miles 57 agricultural lands decreased by 13.7 square miles 12 and upland forests decreased by 12.2 square miles 18 a net loss of 1.8 square miles of wetlands also occurred continued on page 10 changes in landuse of the inland bays watershed from 1992 to 2007 30 20 square miles 10 1.6 0 -10 -12.2 -20 -13.7 0.7 -1.8 25.8 developed/developing water other wetland upland forest agriculture nutrient loads management water quality living resources changes in land use in the inland bays watershed pathogens contaminants climate note proposed development project areas represent full project areas which include some areas left undeveloped such as forests waters and wetlands 9 9


p. 10

land use cont wetlands and forests play an important role in protecting water quality because of their water filtering and storage functions so preserving wetlands and forests helps protect the bays looking ahead the conversion of croplands to development is likely to reduce nutrient loads to the bays over time but development may speed the delivery of pollutants to the bays by generating more runoff due to increased acreage of impervious surfaces the location of development also affects water quality much of the development has taken pace close to waterways where it impacts the natural function of wetlands and shorelines the impor tance of wetlands pleand wetlandsprovidebenefitstopeo trogen theenvironmentbyremovingni ducing fromwaters,trappingsediments,re bitatfor floodinganderosion,providingha impactof plantsandanimals,decreasingthe severestormsandstoringcarbon ebenefits despitepublicappreciationofthes lands,they andfederalprotectionofmostwet ycroplands areincreasinglybeingreplacedb nts stormwaterponds,anddevelopme ofwetland arecentassessmentofthestatus shedfoundthatthe conditioninthewater eexisting beneficialfunctionsofmostofth ebeendegradedand wetlandresourceshav willlikelycontinuetodegrade regulations without strengthened wetland king and and improved permit trac likely enforcement the watershed will and degradation continue to suffer the loss valuable of its wetland resources and the y provide environmental services the 10


p. 11

impervious surfaces watershed condition from1992to2006,impervioussurfacesinthe inlandbayswatershedincreasedby1,203acresto atotalof14,749acres,orabout8%ofthewatershed landarea the creation of new impervious surfaces such as parking lots roadways and the roofs of buildings can increase the amount of runoff entering streams and with it the loads of nutrients pathogens and contaminants the increased runoff causes streams to erode and reduces their natural capacity to remove pollution from waters flowing to the bays increases in bacteria concentrations and chemical contaminants and changes in water flow have been found when watersheds of some estuaries reach 10 impervious surface coverage from 1992 to 2006 impervious surfaces in the inland bays watershed increased by 1,203 acres to a total of 14,749 acres or about 8 of the watershed land area the watersheds of rehoboth bay and little assawoman bay are now over 10 impervious coverage percent of land area covered by impervious surfaces by watershed over time 12 10 of la area land 8 6 4 1990 1994 1998 2002 2006 rehoboth bay l asswmn bay total indian river bay nutrient loads management water quality living resources pathogens contaminants looking ahead impervious surface coverage will continue to increase however new stormwater regulations and ordinances are helping to limit new impervious surfaces and lessen their impact on waters dewey beach fenwick island and south bethany all have ordinances limiting the amount of impervious surface in new developments and dnrec is expected to have improved its sediment and stormwater regulations by early 2012 climate rain gardens like this one at millville town hall trea from impervious surfaces before it enters waterways t runoff 11


p. 12

water quality buffers on croplands croplandscontributethegreatestamountofnutrients tothebaysofanymajorlanduse.buffersofnatural vegetationbetweencroplandsandwaterwayscanbe effectiveatinterceptingmanyofthesenutrients croplands contribute the greatest amount of nutrients to the bays of any major land use buffers of natural vegetation between croplands and waterways can be effective at intercepting many of these nutrients buffers vary in their effectiveness based partly on their width and type of vegetation with wider buffers and forested buffers removing more nutrients a geographic analysis was used to estimate how the average width of forested buffers between cropland and waterways changed overtime only forested buffers wider than 50 feet were detected this underestimates the actual acreage of functioning buffers but nonetheless allows tracking of major changes from 1992 to 2007 the mean buffer width decreased from 274 feet to 201 feet or 27 in 2007 the median buffer width was less than 50 feet for comparison the median buffer width of watersheds on delmarva draining to the chesapeake bay was found to be 134 feet this difference may in part be due to the many unbuffered ditches on cropland in the southern part of the inland bays watershed the outlook for changes in buffer width is unknown average width of forested buffers between waterways and average width of forested buffers between waterways and croplands in the inland bays watershed over time croplands in the inland bays watershed over time 300 300 250 250 feet feet 200 200 150 150 100 100 50 50 1992 1992 1997 1997 2002 2002 2007 2007 forested buffers help to filter nutrients from adjacent croplands before they enter arnell creek 12


p. 13

natural habitat protection and restoration watershed condition since2003,whentrackingbegan 10millionhas beenspenttoprotect3,000acresandrestorenearly 1,000acresofnaturalhabitat our watershed contains a variety of natural habitats that support diverse populations of plants and animals some of them very rare natural habitats also provide scenic beauty recreational opportunities and other ecosystem services acreage of natural habitats is decreasing and becoming fragmented putting pressure on certain sensitive species that require large tracts of forests and wetlands protecting the watershed s remaining high-quality habitats through land purchase and conservation easements and restoring degraded habitats are high priorities of the cib and its conservation partners restoration seeks to re-establish the natural functions of ecosystems by re-introducing native species and removing ecosystem stressors protection is accomplished through · purchase of land · conservation easements that restrict development · creation of preservation agreements · purchase or contribution of development rights since 2003 when tracking began $10 million has been spent to protect 3,000 acres and restore nearly 1,000 acres of natural habitat an additional 1,784 acres were managed to control invasive species this does not include farmland preservation agreements that can also protect some natural habitats protection and restoration activities have decreased due to the recent economic downturn unfortunately when property values are the lowest the least amount of public funding is available for conservation additional incentives are needed for land protection continued on page 14 a acres cumulative acreage of natural habitats protected in the inland bays watershed since 2003 3,000 2,500 2,000 1,500 1,000 500 0 2003 2004 2005 2006 2007 2008 2009 2010 nutrient loads management saltmarsh open field/cropland freshwater wetland upland forest note upland forest category contains an unknown amount of freshwater wetland acreage water quality living resources pathogens contaminants austin okie left and roger jones of the delaware nature conservancy at the 2008 dedication ceremony for the marian r okie memorial wildlife preserve at poplar thicket a 118-acre property on indian river bay photo by steve billups.org swamp pink a rare wetlands perennial 13 13 climate


p. 14

natural habitat protection and restoration cont ed as delmarva fox squirrel listdelawan are extremely rare species in cumulative acreage of restored enhanced habitats in the inland bays watershed since 2003 1,000 tidalwaters 800 600 400 200 0 2003 2004 2005 2006 2007 2008 2009 2010 freshwater saltmarsh open field/cropland freshwater wetland upland forest acres note does not include acreage managed for invasive species saltmarsh enhancement at slough s gut on indian river bay 14


p. 15

indian river inlet flushing watershed condition theamountofwaterpassingthroughtheindian riverinletoveronetidecycleincreasedby4.5times overtheperiod1939to1991.mostofthisincrease occurredsince1970 twice a day tides exchange water and materials through indian river inlet between indian river bay and the atlantic ocean but this has not always been the case in the past the existence of the indian river inlet was subject to the whim of shifting sands and blowing storms and its history was one of migration closing and reopening between 1938-1940 the indian river inlet was stabilized by the construction of rock jetties to protect navigation and the bays seafood industry afterwards the inlet channel began to widen and deepen allowing more ocean water to enter and exit the bays the increased tidal range and volume of seawater entering the bays has likely reduced the amount of fresher water habitats used by spawning fish such as striped bass and shad the increased tidal range also likely decreased the diversity of marsh habitats and may have contributed to their conversion to open water significantly the increased flushing helps remove excess nutrients from the bays by transporting them to the ocean this process is thought by some scientists to be vital to the current health of the bays though no estimates have been made since 1991 the flushing and its effects both positive and negative may have continued to increase indian river inlet tidal flushing over time 2000 nutrient loads management water quality courtesy of the hagley museum library 70.200.09171 aerial image of indian river inlet before stabilization in 1936 living resources mi millions of cubic feet of water f ater passing throu inlet g through 1500 1000 500 0 -500 -1000 -1500 -2000 1930 1940 1950 1960 1970 1980 1990 2000 2010 pathogens contaminants incoming tide outgoing tide indian river inlet 1992 15 climate



no comments yet