2016 S TAT E O F T H E D E L A WA R E INLAND BAYS
Presented by The Delaware Center for the Inland Bays
PB ACKNOWLEDGEMENTS
Report Authors Cardno Delaware Department of Health and Marianne Walch, Emily Seldomridge, Stephanie Briggs Social Services Andrew McGowan, Sally Boswell, and Dan Call Christopher Bason Peter Marsey Delaware Office of State Planning Coordination Lead Editor Delaware Center for the Inland Bays Sally Boswell Brittany Burslem RK&K Robert Collins Jim Eisenhardt This report may be found at Sean Flanagan inlandbays.org. Katie Goerger Sussex County James Hanes, Intern Jayne Ellen Dickerson This project has been funded in part by Steve Maternick Hans Medlarz friends of the Inland Bays, by the Delaware Roy Miller Department of Natural Resources and Molly Struble, Intern Sky Jack Pics Environmental Control, and by the United Focus Group Participants: Susie Ball, TJ Redefer States Environmental Protection Agency Dennis Bartow, Carol Bason, Pat Drizd, under assistance agreements CE09939912 Diane Hansen, Gary Jayne, Pete Keenan, University of Delaware and CE09939913 to the Delaware Center Steve Piron, Ab Ream, Barbara Shamp Scott Andres for the Inland Bays. The contents of this Kevin Brinson document do not necessarily reflect the Delaware Department of Agriculture John Ewart views and policies of the Environmental Christopher Brosch Andrew Homsey Protection Agency, nor does the EPA Robert Coleman Daniel Leathers endorse trade names or recommend the Jimmy Kroon Tye Pettay use of commercial products mentioned in Daniel Woodall Jack Puleo this document. Edward C. Ratledge Delaware Department of Natural Joe Scudlark Design and Production Resources and Environmental Control Bill Ullman Joanne Shipley Michael Bott Jennifer Volk Bruce Cole Ed Whereat GIS Maps John Clark Peter Marsey, Cardno Glenn Davis University of Maryland Baltimore County Andrew Homsey, University of Delaware Kate Fleming Matt Baker Andrew McGowan, CIB Justin Foth Marcia Fox United States Army Corps of Engineers We would like to thank the following Anthony Gonzon Jeffrey Gebert people and organizations for their Michael Greco invaluable assistance with data collection, Edward Hale United States Environmental Protection preparation, analysis, editing, images, Zina Hense Agency and advice for the State of the Bays 2016. Sergio Huerta Finally, without the work of the many Anthony Hummel United States Fish and Wildlife Service dedicated and talented professional Susan Love and volunteer scientists of the Delaware Hassan Mirsajadi United States Geological Survey Department of Natural Resources and Tyler Monteith Judy Denver Environmental Control, the University of Scott Newlin Delaware, and CIB, this report would not Robert Palmer be possible. Alison Rogerson Joe Rogerson The Scientific and Technical Advisory Kathleen Saunders Committee, Delaware Center for the Robert Scarborough Inland Bays Dave Schepens Scott Andres, Chair John Schneider Kari St. Laurent Brittany Sturgis Robin Tyler Sharon Webb David Wolanski Xia Xie Jordan Zimmerman
Top cover photo: Marianne Walch Bottom cover photo: Andrew McGowan TABLE OF CONTENTS
Executive Summary ...... 4–5 How We Assess the Health of the Bays ...... 6
WATERSHED CONDITION ...... 7–18 Human Population Growth ...... 8 Land Use Change ...... 10–11 Impervious Surface Coverage ...... 12–13 Water Quality Buffers on Croplands ...... 14 Salt Marsh Acreage and Condition ...... 15 Natural Habitat Protection and Restoration ...... 16–17 Indian River Inlet Flushing ...... 18
MANAGING NUTRIENT POLLUTION ...... 20–29 Input of Nutrients from Point Sources ...... 22 Input of Nutrients from the Atmosphere ...... 23 Input of Nutrients from Nonpoint Sources ...... 24–25 Agricultural Nutrient Management Practices ...... 26–27 Septic System Conversion to Central Sewer ...... 28 Stormwater Retrofits ...... 29
WATER QUALITY...... 30–39 Algae Concentration ...... 31 Concentrations of Nutrients ...... 32–33 Water Clarity ...... 34 Water Quality Index ...... 35 Dissolved Oxygen Concentration...... 36–37 Seaweed Abundance ...... 38–39 THE INLAND BAYS WATERSHED— QUICK FACTS LIVING RESOURCES ...... 40–54 Bay Grasses ...... 41 • The watershed of the Inland Bays is 292 square Eagle and Osprey Nesting ...... 42 miles of land that drains to 35 square miles of Hard Clam Landings ...... 43 bays and tidal tributaries. Located within Sussex Winter Waterfowl Counts ...... 44–45 County, Delaware on the mid-Atlantic coastal Box: Oyster Enhancement ...... 46 plain of the United States. Blue Crab Abundance ...... 47 • Rehoboth Bay and Indian River Bay are tidally Fish Abundance ...... 48–50 connected to the Atlantic Ocean by the Indian Box: Shore-Zone Fish ...... 51 River Inlet. Little Assawoman Bay is connected Number of Fish Kills ...... 52 by the Ocean City Inlet 10 miles to the south in Recreational Fishing Statistics ...... 53–54 Maryland. HUMAN HEALTH RISKS ...... 55–60 • The Bays are shallow, generally less than 7 feet, Bacteria Pollution ...... 56–57 and have an average tidal range of 3 feet. Approved Shellfish Growing Waters...... 58–59 Fish Consumption Advisories ...... 60
CLIMATE ...... 61–66 Carbon Dioxide Concentration and Air Temperature ...... 62 Sea Level Rise ...... 63 Growing Season Length ...... 64 Precipitation ...... 65 Ocean Acidification ...... 66
References ...... 68–70
3 Watershed Condition Overview
The population of the Inland Bays watershed is growing, and the landscape is rapidly changing from farms and forests to residential and commercial development. Much of the development is concentrated around waterways where its potential impact on water quality is greatest. Since the last report, development increased another 7.8 square miles (11%), replacing agricultural lands, upland forests, and wetlands. With development comes more roads, parking lots and rooftops that generate polluted runoff to the Bays. The watershed as a whole has now exceeded 10% coverage by these impervious surfaces - a tipping point at which water quality has been found to degrade in estuaries. Balancing this is a reduction in the application of fertilizers that occurs when cropland is converted to other land uses. Activities to protect natural habitats in the watershed have nearly stalled since the previous report was published. Saltmarshes are disappearing at higher rates. Funding and incentives for conservation, enhancement of forested buffers, and wetlands protection are needed. The amount of water that moves in and out of the Bays through the Indian River inlet increased (by 11 – 24%) until 2004 and likely continues to improve water quality. What these changes mean long-term for the watershed is uncertain. What is certain as population growth and urbanization continues is that the most effective technology for controlling storm water runoff and treating wastewater will be needed to protect the Bays.
WAEXECUTIVETERSHED COND ISUMMARYTION STATUS BAR WATERSHED CONDITION MANAGING NUTRIENT POLLUTION WATER QUALITY STATUS: FAIR
TREND: NEGATIVE TREND: POSITIVE TREND: POSITIVE TREND: NEGATIVE Development driven by rapid population The remaining two point sources of Water quality is improving in Little growth is increasing the acreage of nutrients should soon be removed from Assawoman Bay and in open waters near impervious surface coverage, adding to the Bays. Nonpoint source pollution the Indian River Inlet. Algae and seaweed urban pollution sources, and stressing remains above healthy limits. Septic blooms have improved in some areas, but habitats. Agricultural pollution is conversions to central sewer have tributaries and canals are still murky and decreasing as land uses change. Increased exceeded goals set in the Pollution oxygen-starved. flushing at the inlet has improved water Control Strategy, but other management quality in open Bay waters. progress has stagnated since 2011.
The population in the watershed than 80% since the 1990s with only more than doubled between 1990 two ‘point sources’ of pollution to and 2010 when the last census was the Bays remaining out of thirteen. conducted. Population growth is driving many of the changes that Voluntary actions to reduce are impacting the Inland Bays. nutrient pollution, prescribed by the Pollution Control Strategy for After a slowdown brought about by agriculture and stormwater, show the recession that began in 2008, little progress, highlighting the need intense development is underway for dedicated funding. again, much of it near waterways where water quality impacts can Human health risks continue for be the greatest. With development those using the Bays for recreation. comes impervious surfaces. Parking Most tributaries and canals continue lots, roadways and roofs now cover to have very poor water quality and over 10% of the watershed’s land are unsafe for swimming or for the harvest of shellfish. area—a point at which studies show Restoring the Bays will require detrimental impacts to water quality As the watershed urbanizes, loss proactive planning and new in estuaries. of wetlands and natural shorelines environmental policies that Nutrient pollution from nitrogen and impact both migrating and resident implement the Inland Bays phosphorus remains the greatest animal populations. Blue Crab Comprehensive Conservation and threat to water quality in the Bays, populations remain low, and Management Plan. recreational fishing and its local but actions taken to reduce nutrient Of greatest need: inputs give reason for optimism. economic benefits have not yet rebounded from losses brought • Legislation that provides funding The volume of tidal water passing about by the recession. Bald for the clean water projects that through the inlet has increased over Eagles and Ospreys are thriving Delawareans say they want. time. This helps flush out nutrients, in the Inland Bays, and hard clam but has also contributed to populations have been stable since • Improved coordination between degradation of marshes in the Bays. the 1970s. Bay grasses, a signature partners responsible for actions species of healthy coastal bays, are outlined in the Inland Bays Overall, water quality in the Inland still largely absent from the Inland Pollution Control Strategy. Bays remains fair to poor, though Bays due to nutrient pollution. Little Assawoman Bay and open • Public participation in the 2018 waters near the inlet are showing Global emissions of carbon dioxide Sussex County Comprehensive some improvements. are bringing higher air temperatures, Plan—to encourage land use and a longer growing season, and policies that protect the natural More than 6,800 homes on septic warmer Bays. Sea level in Delaware resources that are the bounty of systems were connected to central is now rising at a rate of 1.1 feet per healthy Inland Bays. sewer since 2011, and discharges century and is projected to increase from point sources are down more to nearly five feet by 2100. Looking down Love Creek to Rehoboth Bay Photo: TJ Redefer, Sky Jack Pics 4 LIVING RESOURCES HUMAN HEALTH RISKS CLIMATE
TREND: NO TREND TREND: NO TREND TREND: NEGATIVE
Eagles and ospreys are commonly seen Most tributaries and canals are unsafe for Sea level rise and warming temperatures around the Bays. Clams and some fish swimming or for the harvest of shellfish. are a growing challenge for watershed populations are stable. Other species Consumption advisories for Striped Bass communities, residents and Bay such as Blue Crabs and waterfowl have and Bluefish caught in the Bays remain ecosystems. Increased flooding and declined. Oysters and bay grasses are in effect. wetlands loss can be expected. rare in the Bays.
Looking down Love Creek to Rehoboth Bay Photo: TJ Redefer, Sky Jack Pics 4 5 DELAWARE’S INLAND BAYS HOW WE ASSESS THE HEALTH ARE COASTAL LAGOONS— OF THE BAYS bays that lie behind a narrow barrier island that separates them from The 2016 State of the Delaware Inland Bays report is a compilation of the Atlantic Ocean. Traveling down environmental data about the Bays and their watershed. It provides Coastal Highway, through Dewey communities, decision makers, and concerned citizens with robust Beach, Bethany Beach and Fenwick, scientific information that they can use to help restore and protect the the Inland Bays lay to the west. bays and their resources. They are unique places where ‘the To assess the health of the Inland Bays, a suite of environmental rivers meet the sea’…where freshwater indicators was selected. These are specific species and conditions that flowing from the land and down are measured over time to determine how the Bays are changing and tributaries mixes with seawater that how much progress has been made toward restoration goals. flows through inlets carved into barrier Thirty-five individual environmental indicators are grouped by subject islands. matter and presented as the six chapters of the State of the Bays report. A collage of saltmarshes, tidal flats, Each group is assigned a status and a trend by assessing its indicators bay grass meadows, oyster reefs and together. winding saltwater creeks make up • The indicators are based on long-term measurements of this environment. For thousands of environmental parameters and management actions years, the Bays have supported an abundance of fish and birds that come • Status and trends are assigned using best professional judgment and here to feed, reproduce, and grow. reviewed by scientists knowledgeable in these areas. The beauty and productivity of this estuary now supports a thriving human • For each indicator, long-term trends are addressed, as well as culture and economy. short-term changes that have occurred since the previous State of the Delaware Inland Bays report was published in 2011. The Bays are dynamic, constantly changing in response to human The State of the Delaware Inland Bays report is updated and published activities and the climate. every five years. Most of the indicators used in developing this latest report are the same as those presented in the 2011 document. This Fifty or sixty years ago, the Bays were allows us to continue to track trends and progress over the years. A few thought to be generally healthy: new indicators have been added in 2016, as new monitoring data have clear waters with plentiful bay grass become available. meadows, productive oyster reefs, and oxygen levels that supported diverse and plentiful fish populations. STATUS But years of accumulated nutrient pollution and habitat loss have VERY POOR FAIR GOOD VERY changed the Bays to generally POOR GOOD murky waters that are dominated by algae, have very few bay grasses or NEGATIVE TREND POSITIVE oysters, and do not support healthy oxygen levels in many areas. Habitat restoration and major pollution How to Read the Status Bar reductions are needed to restore water quality and achieve a healthy estuary Status is indicated by a dot on the status bar. The farther to the left of once again. 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 Since the adoption of the 1995 Inland positive the status. If the dot is in the center, the status is fair. Bays Comprehensive Conservation and Management Plan and its 2012 A trend arrow pointing to the left indicates a negative trend. A trend Addendum, much progress has arrow pointing to the right indicates a positive trend. No trend arrow occurred toward these goals. Now indicates a neutral or unknown trend. some environmental indicators suggest that accomplishments made under the Plan are bearing fruit and may be moving the Bays back in a healthy direction. But there is still much work to be done.
6 WATERSHED CONDITION WATERSHED NUTRIENT POLLUTION
WaterWATERSHEDshed Condition OCONDITIONverview
The population of the Inland Bays watershed is growing, and the landscape WATER QUALITY The population of the Inland Bays watershed is growing, and the landscape is rapidly changing is rapidly changing from farms and forests to residential and commercial from farmsdevelopment. and forests toMuch residential of the development and commercial is concentrated development. around Much waterways of the development is concentratedwhere its around potential waterways impact whereon water its potentialquality is impactgreatest. on water quality is greatest. Since theSince last report, the last development report, development increased increased another 7.8another square 7.8 miles square (11% miles), replacing agricultural(11%), lands, replacing upland agriculturalforests, and lands, wetlands. upland forests, and wetlands. With developmentWith development comes more comes roads, more parking roads, lotsparking and rooftopslots and rooftopsthat generate that polluted runoff to the Baysgenerate. The watershed polluted runoffas a whole to the has Bays. now The exceeded watershed 10% as coverage a whole byhas these now impervious surfaces -exceeded a tipping 10%point coverage at which bywater these quality impervious has been surfaces—a found to degradetipping point in estuaries at . Balancingwhich this iswater a reduction quality hasin the been application found to of degrade fertilizers in thatestuaries. occurs Balancing when cropland this is convertedis toa reduction other land in uses. the application of fertilizers that occurs when cropland is LIVING RESOURCES Activitiesconverted to protect to natural other landhabitats uses. in the watershed have nearly stalled since the previous report wasActivities published. to protect Saltmarshes natural are habitats disappearing in the watershed at higher haverates .nearly Funding stalled and incentives for conservationsince, enhancementthe previous report of forested was published. buffers, and Salt wetlands marshes protection are disappearing are needed. The amountat higher of water rates. that Funding moves inand and incentives out of the for Bays conservation, through the enhancement Indian River ofinlet increased forested buffers, and wetlands protection are needed. (by 11 – 24%) until 2004 and likely continues to improve water quality. What theseThe changes estimated mean volume long of-term water for moving the watershed in and outis uncertain. of the Bays What through is certain the as Indian River Inlet increased by at least 11% since 1988, likely contributing to population growth and urbanization continues is that the most effective technology for observed improvements in water quality in open Bay waters.
controlling storm water runoff and treating wastewater will be needed to protect the Bays. HUMAN HEALTH RISKS What these changes mean long-term for the watershed is uncertain. What
is certain as population growth and urbanization continues is that the most effective technology for controlling storm water runoff and treating wastewater will be needed to protect the Bays.
WATERSHED CONDITION STATUS BAR WATERSHED CONDITION STATUS: FAIR
TREND: NEGATIVE CLIMATE TREND: NEGATIVE
6 7 WATERSHED CONDITION
HUMAN POPULATION GROWTH Rapid population growth is changing the face of our watershed. This growth LONG-TERM TREND brings development, traffic, more wastewater, and pressure on natural Before 1970, population resources. The success of protection and restoration of the Inland Bays and growth in Sussex County surrounding land is dependent on how we plan for population growth and increased gradually. The land its impacts. around the bays was mostly The 2010 census revealed that 197,897 year-round residents lives in agricultural, and the beach Sussex County, with 89,121 (or 45%) residing in the Inland Bays watershed. communities hosted primarily A method of estimating seasonal and visitor population by measuring seasonal visitors. In the early wastewater flows found that the watershed’s population more than doubles 1990s, the growth greatly in summer. accelerated.
CHANGE SINCE Resident Population PREVIOUS REPORT 300,000 From 1990 to 2010, the 214,075 250,000 Dashed lines indicate projections population of the Inland 200,000 Bays watershed more than doubled. 150,000 102,684 Sussex County 100,000 LOOKING AHEAD Watershed 50,000 ResidentPopulation By 2020, an estimated 0 102,684 year-round residents 1780 1810 1840 1870 1900 1930 1960 1990 2020 2050 are expected in Inland Bays watershed.
The watershed population is expected to increase 15% between 2010 and 2020 and 46% between 2010 and 2040.
8 WATERSHED CONDITION WATERSHED NUTRIENT POLLUTION
WATER QUALITY LIVING RESOURCES HUMAN HEALTH RISKS
Looking south from Jungle Jim’s in Rehoboth Photo: TJ Redefer, Sky Jack Pics CLIMATE
8 9 WATERSHED CONDITION
1% 1%
14% 1992 16% 2007 16% 22%
11% 12%
37% 21% 17% 32%
2012 0.5% 2012 16% 24% with proposed
12% development
17% 31%
10 WATERSHED CONDITION WATERSHED
LAND USE CHANGE How we use the land directly affects water quality in the Bays, since various LONG-TERM TREND land uses result in different types and amounts of pollutants entering Between 1992 to 2012, land waterways. For example, a dense residential area without stormwater use in the watershed changed management contributes four times as much nitrogen pollution to the Bays significantly. Developed lands as a forest of the same size. Agricultural lands also contribute high levels
increased by 33.9 square NUTRIENT POLLUTION of nutrient pollution due to unintentional loss of fertilizers to ground and miles, agricultural lands surface waters. decreased by 18.2 square In 2012, agriculture was the largest land use (31%), followed by miles, and upland forests developed/developing lands (24%), forested lands (17%), wetlands (16%), decreased by 14 square miles. and water (12%). CHANGE SINCE Changes in Land Use from 2007 to 2012 PREVIOUS REPORT Since the previous report, 10 Developed/ Developing developed lands increased by 7.8 square miles (11%), 7.81 Agriculture with continuing declines in Upland Forest WATER QUALITY agricultural lands, upland Open Water forests, and wetlands. 5 Wetlands Other LOOKING AHEAD All indications are that 0.32 extensive development will 0 continue. The 2018 Sussex -0.87 -0.85 County Comprehensive Plan Square Miles Square -1.79 offers the opportunity to plan for growth, open space and -5
protection of natural resources LIVING RESOURCES -4.91 which could have a significant positive impact on the health of the Bays. -10 HUMAN HEALTH RISKS
From 1992 through 2012, agriculture remained the largest land use of the watershed, but the
land area decreased CLIMATE by 18.7mi (15.6% change over time). Developed land increased by 33.9mi Aerial view of Longneck near Mariners Cove Photo: TJ Redefer, Sky Jack Pics (75% change).
10 11 WATERSHED CONDITION
IMPERVIOUS SURFACE COVERAGE The creation of new roads, parking lots, driveways, and rooftops increases the amount of polluted stormwater runoff entering streams and the Bays. These impervious surfaces reduce infiltration of rainwater into the ground and contribute to flooding. Stormwater control practices such as retention ponds, raingardens, infiltration areas, and permeable pavements reduce these impacts. Studies have shown that noticeable degradation to the water quality of estuaries begins when their watershed exceeds 10% imperviousness. The Inland Bays watershed as a whole has reached 10.4% impervious cover. Rehoboth and Little Assawoman Bay watersheds are even higher—13.7% and 12.7%, respectively. The most densely developed communities may exceed 50% imperviousness.
Rehoboth Bay comes to Dewey Beach September 1, 2016
12 WATERSHED CONDITION WATERSHED
LONG-TERM TREND Since 1992, the percentage of land in the watershed covered with impervious surface increased by 22%. NUTRIENT POLLUTION The largest increase occurred between 2001 and 2006.
CHANGE SINCE PREVIOUS REPORT Development slowed during the recession that began in 2008, as did the rate of increase in impervious surface coverage. Data for years more recent than 2010 are not yet available. WATER QUALITY
LOOKING AHEAD Improving economic conditions have revived development activities postponed due to the recession, so impervious surface coverage will continue to increase. Limitations on the amount LIVING RESOURCES of impervious surface in new developments potentially could be incorporated into Sussex County’s 2018 Comprehensive Plan.
Land Area Covered By Impervious Surfaces HUMAN HEALTH RISKS 20,000 11% 10.36% 10.04% 10% 19,000 Studies have shown 8.84% 8.52% 8.68% 9% that noticeable 18,000 degradation to the 8% water quality of Acres 17,000 estuaries begins 7% when their watershed CLIMATE 16,000 CoveredLand % Area exceeds 10% 6% imperviousness. 15,000 5% The Inland Bays 1992 1996 2001 2006 2010 watershed as a whole has reached 10.4% impervious cover. 12 13 WATERSHED CONDITION
WATER QUALITY BUFFERS ON CROPLANDS Agriculture is still the largest land use in the watershed and contributes LONG-TERM TREND more nutrient pollution to the Bays than any other major land use. Buffers From 1992 to 2012, the of natural vegetation between croplands and waterways can intercept and average buffer width remove many of these nutrients. decreased from 274 feet to Buffers vary in their effectiveness based partly on their width and type 206 feet (or 25%). of vegetation. Wider buffers and forested buffers are more effective in removing nutrients from runoff and groundwater. CHANGE SINCE PREVIOUS REPORT A geographic analysis was used to estimate how the average width Mean buffer width continued of forested buffers between cropland and waterways has changed to decrease since the previous overtime. Only forested buffers wider than 50 feet were detected, which report, down 1.6% since 2007. underestimates the actual acreage of functioning buffers. Still, this allows tracking of major changes. LOOKING AHEAD The outlook for changes in Average Width of Forested Buffers buffer width is uncertain. Between Waterways and Croplands Due to long term declines in government incentives to 300 establish and maintain buffers, their width is expected to continue to decrease. 250
200 Feet
150
100 1990 1995 2000 2005 2010 2015
Forested bufers can remove over 80% of nutrient pollution from waters on their way to the Bays.
Love Creek at Mulberry Knoll looking downstream to Arnell Creek and Rehoboth Bay Photo: TJ Redefer, Sky Jack Pics 14 WATERSHED CONDITION WATERSHED
SALT MARSH ACREAGE AND CONDITION Saltmarshes provide highly valuable LONG-TERM TREND services to people. They reduce flooding 22% of the Bays’ salt marshes and erosion from storms, filter pollutants, were lost between 1938 and trap and store carbon, and provide critical 1968 mostly to excavation habitat for fish and wildlife. and filling for development. NUTRIENT POLLUTION The decline has continued, Nearshore development and sea level but at a slower pace due to rise are contributing to the loss of Delaware’s 1973 Wetlands salt marshes. A significant feature of Act that legally protected many Inland Bays salt marshes is the saltmarshes. appearance of open water pools in the interior of the marsh. These areas are drowning due to sea level rise and CHANGE SINCE because old ditches dug to control PREVIOUS REPORT mosquitos are now causing water to be There has been a marked trapped on the marsh surface. increase in the amount of interior open water in The total acreage of salt marshes fringing salt marshes since 1992, WATER QUALITY the Bays was 7,300 when last inventoried indicating accelerating in 2007—a net loss of over 3,500 acres degradation and loss. since 1938. The loss of marshes is Salt Marsh Cordgrass particularly harmful to the water quality Spartina alternfora LOOKING AHEAD and living resources of the Bays. Most direct destruction of salt marsh by human impacts Acres of Salt Marsh in the Inland Bays has been halted. Now the major cause of tidal marsh 11,000 loss is erosion and ‘drowning’ of wetlands due to land LIVING RESOURCES 10,000 subsidence and sea level rise. With rising sea levels 9,000 and nearshore development, the important services of Acres 8,000 this resource will continue to disappear.
7,000
6,000
1930 1940 1950 1960 1970 1980 1990 2000 2010 HUMAN HEALTH RISKS
Salt Marsh Degradation 800
600 Salt marshes reduce flooding and erosion 400 from storms, filter pollutants, trap and store carbon, and CLIMATE 200 Acres of InteriorPooling provide critical habitat for fish and wildlife. 0 1930 1940 1950 1960 1970 1980 1990 2000 2010
14 15 WATERSHED CONDITION
NATURAL HABITAT PROTECTION AND RESTORATION Many types of natural habitats exist in the watershed, including forests, wetlands, meadows and beaches. They support a diversity of plants and animals, some of them rare. They also provide scenic beauty and recreational opportunities that are valued by visitors and residents. Habitats are being lost due to changes in land use. Natural areas have become increasingly fragmented, stressing or eliminating some sensitive species that require large tracts of wetlands or forests. Protecting the remaining high-quality natural areas and restoring degraded habitats are priorities for the CIB and its conservation partners. Protection is accomplished through purchase of land or conservation easements that restrict development. Restoration seeks to reestablish the natural ecosystems by reintroducing species and removing stressors.
James Farm Ecological Preserve on Indian River Bay Planting trees at Angola Neck Preserve
16 WATERSHED CONDITION WATERSHED
Brown-headed nuthatch Photo: Julie Memmolo LONG-TERM TREND Since tracking began in 2003, nearly $12 million has been spent to protect 3,000 acres and restore over 1,500 acres of natural habitat. Most
of that progress occurred NUTRIENT POLLUTION
before 2010.
CHANGE SINCE PREVIOUS REPORT Since our previous report, progress on protection of natural habitat has nearly stalled and restoration has slowed. Since 2011, only 97 acres were protected and 530 acres restored. This WATER QUALITY slowdown is attributable Planting trees at Angola Neck Preserve to reductions in funding programs for public conservation programs and high land values for development.
LOOKING AHEAD Progress in habitat protection
and restoration will be LIVING RESOURCES closely tied to availability of funding and incentives. New and innovative approaches to land conservation in the Inland Bays are needed if natural habitats are continued to be protected. HUMAN HEALTH RISKS
Natural Habitat Protection & Restoration 3,500
3,000
2,500 Protecting remaining high-quality natural 2,000 areas and restoring 1,500 degraded habitats are CLIMATE
Cumulative Acres Cumulative 1,000 priorities for the CIB and its conservation 500 partners. 0 2003 2006 2009 2012 2015
16 17 WATERSHED CONDITION
INDIAN RIVER INLET FLUSHING Twice each day, the tides carry billions of cubic feet of salty ocean water into LONG-TERM TREND Indian River Bay where it mixes with freshwater entering from streams and In the late 1960s, the increase groundwater. in tidal flushing accelerated, Years ago, the inlet to Indian River Bay was shallow and moved around; it such that 20 years later the cut through the barrier island at various locations, blown out by one storm, amount of water passing closed up by another. through during one tide cycle had increased by over four The inlet as we know it today was stabilized in the late 1930s by the times. construction of rock jetties. Since then the inlet has deepened over time, passing greater volumes of water and increasing the tidal range of the Bays. This has led to a long-term increase in the salinity of the Bays and CHANGE SINCE contributed to degradation of marshes. PREVIOUS REPORT Increasing flushing also results in the flushing out of nutrient pollution from A 2004 estimate indicated the Bays to the ocean. This likely contributes to improved water quality seen the volume of tidal flushing in the open bay waters that are most influenced by the tide. continued to increase by 11– 24% compared to the previous measurement in 1988.
LOOKING AHEAD The future rate of change in tidal flushing is uncertain. However, exchange through the inlet will continue to benefit water quality in the Bays.
The location of the inlet naturally shifted locations, as it was opened and closed by storms, until the early 20th century when it was secured in place by the Army Corps of Engineers. Photo: Delaware Seashore State Park
Indian River Inlet Flushing Over Time 2,500 Years ago, the inlet to 2,000 Indian River Bay was 1,500 Incoming Tide shallow and opened 1,000 and closed by storms. 500 The inlet as we know 0 it today was deepened -500 and stabilized in Passing Through Inlet Through Passing -1,000 Outgoing Tide the late 1930s by the Millions of Cubic Feet ofWater -1,500 construction of -2,000 1930 1940 1950 1960 1970 1980 1990 2000 2010 rock jetties.
18 WATERSHED CONDITION WATERSHED
Indian River Inlet looking northwest to Rehoboth Bay Photo by Gordon Campbell / At Altitude Gallery NUTRIENT POLLUTION
WATER QUALITY LIVING RESOURCES HUMAN HEALTH RISKS CLIMATE
18 19 MANAGING NUTRIENT POLLUTION Nutrient pollution is the largest problem facing the Inland Bays. Point source pollution originates from a pipe, such as discharge from a wastewater treatment plant. Nonpoint source pollution originates from diffuse sources and enters the Bays through groundwater and surface runoff. Sources include fertilizers, septic systems, land application of wastewater, and stormwater runoff. Atmospheric sources originate from the emissions of power plants, automobiles, and agriculture that later deposit directly onto the surface of the Bays. The maximum amount of nutrient pollution that a water body can receive and still support healthy environmental conditions is called its Total Maximum Daily Load (TMDL). In 1998, state regulations established target loads for the Inland Bays. The regulations require elimination of all point sources, a 40 to 85% reduction of nonpoint source loads, and a 20% reduction of loads from atmospheric deposition. In 2008, the Delaware Department of Natural Resources and Environmental Control enacted a Pollution Control Strategy (PCS) that laid out a series of regulatory and voluntary actions needed to meet the TMDL. After decreasing by over 80% since the 1990s, point source pollution decreased only slightly since the last report, and two point sources remain in the Bays. Nonpoint source nitrogen loads remained far in excess of healthy limits in all bays, but loads to Little Assawoman Bay may now be decreasing. Phosphorus loads on average were within healthy limits for Rehoboth and Little Assawoman Bays, but continue to exceed healthy limits for Indian River Bay. Atmospheric nitrogen loads are now within healthy limits. Substantial progress was made on conversions of septic systems to central sewer, far surpassing the pollution reduction goal. Voluntary agricultural and stormwater nutrient management practices yielded very little progress, highlighting the need for dedicated funding for these most important bay restoration actions.
MANAGING NUTRIENT POLLUTION
TREND: POSITIVE
20 WATERSHED CONDITION WATERSHED
Excess nutrients from NUTRIENT POLLUTION
fertilizers, wastewater, and runoff cause blooms of microscopic algae. These, along with sediments in runoff, reduce water clarity which inhibits growth of bay grasses. Oxygen levels fluctuate naturally on a daily cycle in our shallow Bays. But when nutrient pollution is high, the cycles become WATER QUALITY extreme, and very low oxygen harms fish and invertebrates. LIVING RESOURCES
In a healthy bay, there is little algae, light reaches the bottom allowing bay HUMAN HEALTH RISKS grasses to grow, a greater diversity of fish and shellfish are present, and oxygen is plentiful and relatively stable. CLIMATE
20 21 MANAGING NUTRIENT POLLUTION
INPUT OF NUTRIENTS FROM LONG-TERM TREND As wastewater facilities POINT SOURCES have improved treatment or removed their discharges, In 1990, thirteen point sources of pollution discharged to the Bays. Now only pollution to the Bays has two remain: the City of Rehoboth Beach, and the Allen Harim facility near decreased dramatically. From Indian River. 1990 to 2009, pollution loads Since the last report, the removal of Rehoboth Beach’s wastewater discharge from point sources decreased from Rehoboth Bay was again delayed, while the Town of Millsboro removed by 407 lbs. per day of nitrogen its discharge from the Indian River in August of 2015. Lewes is permitted to (82%) and 44 lbs. per day of maintain its discharge to the Lewes & Rehoboth Canal, and makes up for the phosphorus (87%). small amount of pollution that reaches the Bays by funding manure relocation from the watershed. CHANGE SINCE PREVIOUS REPORT Loads of Nutrients from Point Sources 600 60 From 2009 to 2015, pollution continued to decrease slightly Townsend/Mountaire processing plant )
removes discharge from Indian River y by 0.83 lbs. per day of a ) y
500 50 d / a nitrogen and 0.71 lbs. per day s d u / r
n Rehoboth
o of phosphorus. e
upgrades h g p
o 400 40
treatment plant s r t o i h N P
l l a
a LOOKING AHEAD t 300 30 t o o T T
s Pollution from point sources s b b l l ( (
Millsboro removes is anticipated to continue to d
200 20 d
a discharge from Indian River a o
o decrease to zero, as required L L
n s by the Total Maximum Daily e u r g
100 10 o o
r Total Nitrogen
h Load regulation. Rehoboth t i p s
N Total Phosphorus
o plans to divert its discharge h
0 0 P to an ocean outfall by 2018. 1990 1994 1998 2002 2006 2010 2014 Allen Harim is in discussions with DNREC about how to address its point source. The reduction in pollution from the removal of Millsboro’s discharge will be realized in the next report.
In 1990, thirteen point sources of pollution discharged to the Bays. Now only three remain.
22 WATERSHED CONDITION WATERSHED
INPUT OF NUTRIENTS LONG-TERM TRENDS Since the early 1990s, FROM THE ATMOSPHERE atmospheric nitrogen loads have decreased due to Nutrients are deposited from improved federal emission the atmosphere directly into the standards for power plants Bays during both wet and dry and automobiles. Phosphorus NUTRIENT POLLUTION
weather. Excess nitrogen in the loads have increased slightly atmosphere comes from coal- for unknown reasons. burning power plants, automobiles, and agriculture. Phosphorus in the atmosphere may originate from CHANGE SINCE combustion, natural vegetation, PREVIOUS REPORT blown soil particles, sea spray, and Since the previous report, herbicide application. atmospheric inputs of nitrogen have continued a Deposition of nitrogen is of slight decrease. Retirement of most concern for Bay health, and coal-fired generating units at now atmospheric nitrogen loads the Indian River Power Plant meet their pollution reduction goal may have contributed to the WATER QUALITY on average. improvement. Phosphorus loads have continued to increase slightly.
LOOKING AHEAD Nitrogen Load from the Atmosphere Reductions in atmospheric 800 nitrogen loads should continue as a result of both increasing fuel economy standards and the federal 600 Clean Air Act and Clean LIVING RESOURCES Power Plan that requires reduced emissions from power plants. Should phosphorus 400 Goal from the atmosphere continue
Nitrogen Load (lbs/day)NitrogenLoad to increase, investigation into its specific sources may be needed. 200 1992 1996 2000 2004 2008 2012 2016 HUMAN HEALTH RISKS
Phosphorus Load from the Atmosphere 9
8 Atmospheric nitrogen loads 7 meet their pollution reduction goal on
6 average. CLIMATE
No pollution reduction goal Phosphorus LoadPhosphorus(lbs/day) 5 developed
4 1992 1996 2000 2004 2008 2012 2016
22 23 MANAGING NUTRIENT POLLUTION
INPUT OF NUTRIENTS FROM NONPOINT SOURCES Nonpoint source pollution comes from fertilizers, animal wastes, and human wastewater transported through runoff or groundwater. It is by far the largest source of nutrient pollution. Input (or ‘loads’) of nutrients from nonpoint sources are estimated from monitoring the major streams that drain to the Bays. Many years are needed to detect changes, because stream flow is variable, and groundwater carrying nutrients may take decades before entering streams. Loads of Nitrogen from Nonpoint Sources Inputs of nitrogen remained far in excess of healthy limits in all three Indian River Bay Bays. Indian River Bay had average 8,000 inputs more than six times the healthy limit. 6,000 Inputs of phosphorus, on average, remained within healthy limits in 4,000 Rehoboth and Little Assawoman 2,000 Bays, but some years exceeded Goal limits. Phosphorus loads in Indian River Bay were nearly twice the 0 healthy limit. 2,000 L. Assawoman Bay
1,600
1,200
800 Goal 400
0 Nitrogen Load (lbs/day) Load Nitrogen
3,000 Rehoboth Bay 2,500 2,000 1,500 1,000 500 Goal 0 Nitrogen Load (lbs/day) Load Nitrogen
24 WATERSHED CONDITION WATERSHED
CHANGE SINCE PREVIOUS REPORT Since the last report, nitrogen inputs to Little Assawoman Bay have decreased but inputs did not change to Rehoboth and Indian River NUTRIENT POLLUTION Bays. No short-term trends in phosphorus inputs were observed.
LOOKING AHEAD Sustained phosphorus reductions are credited to improved nutrient management on farms and the conversion of cropland to development with
stormwater controls. Sixteen WATER QUALITY Runoff from a construction site on Dirickson Creek years after Total Maximum Daily Load regulations were Loads of Phosphorus from Nonpoint Sources enacted, nitrogen loads have not decreased. This has Indian River Bay been enough time to allow 120 nearly half of the polluted 100 groundwater to flush through 80 aquifers and into streams. 60 Goal Decreases are expected as cleaner water begins to enter LIVING RESOURCES 40 streams over time. However, 20 significant improvement 0 hinges on the widespread implementation of all actions 60 L. Assawoman Bay of the Pollution Control Strategies. 50 40 Goal
30 HUMAN HEALTH RISKS 20 10 0 Phosphorus Load (lbs/day) Load Phosphorus 80 Rehoboth Bay Inputs of nitrogen 60 remained far in 40 excess of their healthy limits in all 20 Goal three Bays. Indian CLIMATE River Bay had 0 average inputs over six times its healthy limit.
24 25 MANAGING NUTRIENT POLLUTION
AGRICULTURAL NUTRIENT MANAGEMENT PRACTICES Agriculture is the largest land use in the watershed, and it contributes the most pollution through the unintentional loss of fertilizers to waters. Best management practices for nutrients significantly reduce pollution and can improve soil fertility. Agricultural practices of the Pollution Control Strategy account for over three quarters of the needed pollution reductions. Progress since 2005, when tracking began, is mixed. Of the 8 practices, only Nutrient Management Planning (a regulatory requirement) has met its goal. Two other practices have achieved over 50% of their goals, while the remaining five practices have had little progress. Some goals are under-reported, because practices implemented without government assistance may not be tracked.
Progress Toward Pollution Control Strategy Agricultural Nutrient Management Practice Goals (since the year 2005)
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Practice Goal
Implement Nutrient 100% of farms 100% Mgmt. Planning
Establish Cover Crops Avg. of 37,637 18% acres/year
Establish Forested 3,037 acres 1% Waterway Buffers
Establish Grassed 1,718 acres 2% Waterway Buffers
Restore Wetlands 4,147 acres 1% on Former Cropland
Build Poultry Manure 50 structures 66% Sheds or Composters
Relocation & Alternative Avg. of 20,909 Use of Manure tons/year 53%
Treat Cropland with 450 acres 12% Water Control Structures
26 WATERSHED CONDITION WATERSHED
CHANGE SINCE PREVIOUS REPORT Since the last report, Nutrient Management Planning increased from 95% of farms to 100% of farms. An additional 24 poultry manure NUTRIENT POLLUTION sheds or composters were built, manure relocation increased slightly, and 2 water control structures were built. Since the last report, little overall progress has been made on implementing agricultural nutrient management practices, which are by far the most important for restoring the Inland Bays. WATER QUALITY LOOKING AHEAD Since almost all practices are voluntary, implementation is driven by government investment in subsidies. According to the Pollution Control Strategy, for all of the remaining agricultural practices to meet their goals an estimated $4 million LIVING RESOURCES investment per year would be needed. (Adjusted for inflation) HUMAN HEALTH RISKS
Since the last report, little overall progress has been made on implementing agricultural nutrient management practices, CLIMATE which are by far the most important for restoring the Inland Bays. Field near Love Creek Photo: TJ Redefer, Sky Jack Pics 26 27 MANAGING NUTRIENT POLLUTION
SEPTIC SYSTEM CONVERSION CHANGE SINCE PREVIOUS REPORT TO CENTRAL SEWER Since 2011, the equivalent A properly maintained septic system leaches 10.6 lbs. of nitrogen and 0.7 lbs. of 6,813 single family homes of phosphorus to groundwater each year. When multiplied by the estimated were connected to central 8,292 systems in the watershed, the total pollution contribution of septics sewer. Johnson’s Corner, is nearly 89,000 pounds of nitrogen yearly and more than 5,800 pounds of Angola, and Oak Orchard phosphorus. sewer districts received the most new connections. During Central sewer service allows a higher level of sewage treatment and eliminates this time, the Pollution Control pollution from septic systems. Strategy goal for septic conversion was far surpassed. Since the 1970s, Sussex County has facilitated the conversion of an estimated 50,801 septic systems to central sewer. While new septics are continually permitted, the total number of septics in the watershed has decreased with LOOKING AHEAD central sewer expansion. In 2016, property owners voted to include 713 homes on septics into the new Cumulative Number of Equivalent Dwelling Units (EDUs) Converted from Septic to Central Sewer Herring Creek Sewer District. Regulations requiring a 60,000 greater pollution removal for new septic systems were 50,801 implemented in 2014. These 50,000 positive developments will 43,988 Goal continue to keep nutrients and bacteria out of the Bays. 40,000 EDUs
30,000
20,000 1992 1996 2000 2004 2008 2012 2016
While new septics are continually permitted, the total number of septics in the watershed has decreased thanks to central sewer expansion.
Dirickson Creek Team paddling up the Creek 28 WATERSHED CONDITION WATERSHED
STORMWATER RETROFITS LOOKING AHEAD 4,399 acres remain to be As stormwater moves overland, it picks up and carries pollutants retrofitted to meet the from lawns, streets, and industrial facilities into streams and the Bays. pollution goal. The rate Developments in Delaware constructed prior to 1990 were not required to of stormwater retrofit control stormwater, so they contribute high levels of stormwater pollution. implementation is not expected to increase unless
Stormwater retrofits are stormwater management facilities in locations NUTRIENT POLLUTION public or private investment where controls did not previously exist or were ineffective. The Inland Bays in the practices increases. Pollution Control Strategies call for the creation of stormwater retrofits to This underscores the need for treat 4,500 acres of lands developed prior to 1990. stormwater regulations that Currently, 101 acres of the watershed have received stormwater retrofits. protect water quality and that The Town of South Bethany contributed the most to this goal with the are enforced. completion of the Anchorage Canal Sotrmwater Retrofit Project. The CIB, working with the Delaware Department of Transportation and the surrounding communities, installed a series of attractive raingardens, ponds, wet swales, and infiltration areas were created over six years.
Cumulative Area of Development Retrofitted WATER QUALITY with Stormwater Controls 150
Pollution Control Strategy 100 Goal = 4,500 acres LIVING RESOURCES Acres Treated 50
0 2010 2011 2012 2013 2014 2015 2016 HUMAN HEALTH RISKS
A series of attractive raingardens, ponds, wet swales, and infiltration areas were created as part of the Anchorage Canal CLIMATE Stormwater Retrofit Project along the Route 1 corridor in South Bethany. Anchorage Canal Stormwater Retrofit Project by Sea Colony 28 29 WATER QUALITY Measures of water quality are the most basic indicators of Bay health. They are key measures of the effectiveness of actions taken to reduce pollution to the Bays. The six water quality indicators are based on the minimum requirements necessary for reestablishment of bay grasses and healthy dissolved oxygen levels. Each water quality indicator individually is useful to assess changes in the health of the Bays, and collectively they provide a clearer picture of ecological conditions. The water quality information used in this report comes from more than 30 long-term monitoring sites located in tidal portions of the Bays. Data are collected by both the Department of Natural Resources and Environmental Control and the University of Delaware’s Citizen Monitoring Program. Overall, water quality in the Inland Bays remains fair to poor, but is improving. Compared to five years ago, nutrient and algae concentrations have improved in some areas. Many places have seen modest long-term positive trends in phosphorus and algae levels. Water clarity and dissolved oxygen in the Bays, however, have seen no significant long-term improvements. Although seaweed abundance is down compared to the 1990s, blooms still occur. Few areas had water quality conditions that are thought to allow bay grasses to reestablish. Most tributaries and canals continue to have poor water quality. Water quality improvements are, however, being seen near the Indian River Inlet and in Little Assawoman Bay. With its smaller ratio of land to water, and high water tables, Little Assawoman is likely to be the first Bay to respond to improved watershed management. Looking Ahead Until nutrient inputs to the Bays decrease, water quality is likely to remain impaired, particularly in tributaries. Increased tidal flushing through the inlet has likely contributed to better water quality in parts of Indian River and Rehoboth Bays.
WATER QUALITY
TREND: POSITIVE
30 WATERSHED CONDITION WATERSHED
ALGAE CONCENTRATION In a healthy bay, floating microscopic algae provide food for fish, shellfish LONG-TERM TREND and other invertebrates. When too many nutrients are added to the water Over the long-term, algae may grow out of control, and algal blooms appear. If blooms persist, algae levels in a number they cloud the water so that bay grasses are deprived of light and cannot of tributaries and Little grow.
Assawoman Bay have NUTRIENT POLLUTION
Chlorophyll a is a green pigment in algae. Concentration of this pigment in improved. Indian River, the Bays indicates the abundance of algae. Levels below 15 milligrams per however, has shown no liter of water are considered healthy. improvement. From 2011 to 2015, the majority of locations sampled in the Bays (73%) met this standard. Indian River and Dirickson Creek had high levels of CHANGE SINCE algae that often were much worse than the standard. PREVIOUS REPORT Algae concentrations in the Bays have decreased since the previous report was published. The number of sampling
stations meeting the standard, WATER QUALITY compared to five years ago, has increased by 36%. Of all the water quality indicators, algae concentration has improved the most. LIVING RESOURCES HUMAN HEALTH RISKS
Chlorophyll a is a green pigment in algae. Concentration of this pigment in
the Bays indicates an CLIMATE abundance of algae.
30 31 WATER QUALITY
Testing the waters on Love Creek Photo: Judy Britz
32 WATERSHED CONDITION WATERSHED
CONCENTRATIONS OF NUTRIENTS Nitrogen and phosphorus are nutrients necessary for the growth of LONG-TERM TREND beneficial bay grasses, seaweeds and algae. But an excess of these Nutrient concentrations have nutrients has caused overabundances of algae and seaweeds, murky water, not changed significantly low oxygen levels, and disappearance of bay grasses. at most monitoring sites over last 10- to 15-year NUTRIENT POLLUTION
Studies have determined standards for nutrient concentrations that period. Conditions at three will result in healthy oxygen levels and clear waters that allow bay grasses stations are degrading as to reestablish. nutrient concentrations Over the period 2011 to 2015, 52% of monitoring stations met the have increased. Long-term standard for nitrogen concentration. Most sites that met the standard improvements have occurred are located in open bay areas near the Indian River Inlet and in Little at sites closest to the Indian Assawoman Bay. Tributaries generally did not meet nitrogen standards, River Inlet, likely because the and concentrations in Indian River and Guinea Creek are particularly high. tidal flow through the inlet has increased over time. Forty-six percent of stations met the standard for phosphorus. More tributary sites meet the phosphorus standard than for nitrogen. CHANGE SINCE Phosphorus concentrations are relatively low in Little Assawoman Bay, WATER QUALITY partly because its lower salinity keeps phosphorus bound to bay sediments PREVIOUS REPORT and out of the water. There are some signs of progress. Compared to five years ago, concentrations of both nitrogen and phosphorus have moderately improved. Roughly half of the sites now meet nutrient standards. Only a third did previously. LIVING RESOURCES HUMAN HEALTH RISKS
52% of monitoring stations met the standard for nitrogen concentration.
46% of stations met CLIMATE the standard for phosphorus.
32 33 WATER QUALITY
WATER CLARITY Because all plants need sunlight LONG-TERM TREND to grow, clear water is essential While water clarity in Little for underwater bay grasses to Assawoman Bay improved over reestablish in the Inland Bays. a 10- to 15-year period, five sampling sites in Indian River Algae, sediments, and organic matter Bay and the Lewes-Rehoboth floating in the water all reduce clarity Canal decreased in clarity. and prevent sunlight from reaching the bay bottom to support plant life. CHANGE SINCE Water clarity is measured by lowering PREVIOUS REPORT a black and white Secchi disk into the More sites in Little Assawoman water until its markings can no longer Bay now meet the water clarity be seen. When all other conditions standard than in 2011. Waters are right, bay grasses can grow in on the western side of Indian shallow waters with an average Secchi depth of at least 2.2 feet. River Bay became less clear. From 2011 to 2015, 55% of water quality monitoring sites in the Bays met The status of other bay areas or exceeded this standard. Little Assawoman Bay and areas near the Indian has not changed. River inlet were clearest, while tributaries were murky and below standard.
Because all plants need sunlight to grow, clear water is essential for underwater baygrasses to reestablish in the Inland Bays.
34 WATERSHED CONDITION WATERSHED
WATER QUALITY INDEX The Water Quality Index combines the previous four indicators (nitrogen LONG-TERM TREND and phosphorus concentrations, algae concentration, and water clarity) The only significant long- into an integrated measure of whether conditions are present to support term trends in the index value the reestablishment of eelgrass. were in Little Assawoman Bay (two stations improving, one NUTRIENT POLLUTION
The index ranges from 0 (water quality least supportive of eelgrass) to degrading). 1.0 (water quality that will support eelgrass reestablishment when other conditions allow). Index values from 0.90 to 0.99 may support some reestablishment and growth. CHANGE SINCE PREVIOUS REPORT 41% of monitoring sites in the Bays had an index value of at least 0.90, The index values for Vines suggesting that bay grass restoration efforts could be successful in these Creek, and lower Indian River areas where other physical conditions are met. Again, these areas are have improved over the past found mostly in Little Assawoman Bay, and in the open water areas of the five years, but both remain bays near the inlet. Two sites, in Dirickson Creek and upper Indian River, below standard. Parts of Little had particularly low indices of water quality. Assawoman Bay that were below standard in 2011 now meet minimum requirements WATER QUALITY for growth of eelgrass. LIVING RESOURCES HUMAN HEALTH RISKS
41% of monitoring sites in the Bays had an index value of at least 0.90, suggesting that bay grass CLIMATE restoration eforts could be successful in these areas where other physical conditions are met.
34 35 WATER QUALITY
DISSOLVED OXYGEN CONCENTRATION All living creatures in the Bays—from swimming fish, shrimp and crabs to the clams and worms that burrow into the mud—need oxygen to survive. Dissolved oxygen levels that are high and stable support diverse and healthy populations of bay life. Oxygen levels in shallow bays naturally cycle over 24 hours. During the day, plants and algae release oxygen into the water through photosynthesis. At night, plants, algae, and animals continue to respire and draw oxygen out of the water. But nutrient pollution makes these cycles extreme by fueling algal blooms. When the excessive algae respire at night, they can cause oxygen to drop below healthy levels. The dissolved oxygen indicator shows the percent of summer mornings that oxygen levels fall below the healthy standard of 4 milligrams of oxygen per liter of water. Zero to 10% of mornings is considered healthy. Higher percentages increasingly impact the feeding, growth and survival of aquatic life in the Bays. Dissolved oxygen levels in well-flushed, open water areas of the Bays meet the standard most of the time. However, many nearshore areas and tributaries have unhealthy oxygen levels.
Snapshot of Continuously Monitored Dissolved Oxygen Concentrations During a Typical Period in August (2009), in Two Tidal Rivers With Contrasting Levels of Nutrient Pollution 8 i ed i i e e d d 7 e ed 6
5
4
3
2 Dissolved Oxygen (mg/L) Oxygen Dissolved 1 e di i e e ed 0 8/29 12:AM 8/30 12:AM 8/31 12:AM 9/1 12:AM 9/2 12:AM
Nutrient pollution causes oxygen levels to decrease and fluctuate wildly. This causes unsustainable oxygen levels for some fish, shellfish and invertebrates.
36 WATERSHED CONDITION WATERSHED
LONG-TERM TREND Four sites have shown long- term improvement, with increasing levels of oxygen on summer mornings, while four NUTRIENT POLLUTION showed decline. There are no overall trends or patterns in the location of these sites.
CHANGE SINCE PREVIOUS REPORT Since the previous report, dissolved oxygen has improved in the upper Indian River at Millsboro and Herring Creek. Oxygen levels in Guinea Creek are less healthy. WATER QUALITY
Diamondback terrapin Photo: Jay Fleming LIVING RESOURCES HUMAN HEALTH RISKS
Oxygen levels in shallow bays naturally cycle over 24 hours. During the day, plants and algae release
oxygen into the CLIMATE water through photosynthesis. At night, plants and animals continue to respire and draw oxygen out of the water. 36 37 WATER QUALITY
SEAWEED ABUNDANCE Seaweeds are a natural part of the Inland Bays ecosystem. They provide food and habitat for many invertebrates, fish, and water birds. The amount of seaweed present in the Bays is a good indicator of nutrient pollution. When nutrients are in excess, seaweeds can grow rapidly and become overabundant. This was the case in the late 1990s when seaweeds bloomed so much that they smothered shellfish, depleted oxygen, killed bay grasses, and fouled beaches. Currently fewer dense blooms occur, but levels of seaweed are still high enough to prevent bay grasses from reestablishing in many locations.
Brant eating Sea Lettuce Photo: Dennis Bartow
38 WATERSHED CONDITION WATERSHED
LONG-TERM TREND Seaweed abundance dropped significantly between 1999 and 2009, perhaps in response to decreases in NUTRIENT POLLUTION phosphorus loads to the Bays.
CHANGE SINCE PREVIOUS REPORT On a whole, seaweed levels in the Bays remain below those seen in 1999. But densities of seaweed were relatively high at a few sites in 2012, and the overall average density may be increasing. The meaning of this is unclear, and more WATER QUALITY years of data are needed to determine if this is a trend. LIVING RESOURCES
Seaweed Abundance HUMAN HEALTH RISKS in Rehoboth and Indian River Bays
1.2
Seaweeds provide 0.8 food and habitat for many invertebrates, fish, and water birds.
0.4 But when nutrients CLIMATE are in excess, seaweeds can grow