How would a carbon tax affect DC?

Nature's fuel

The right thing in climate policy for all the big countries is a carbon tax, which is simpler and less vulnerable to fluctuations in emissions than cap-and-trade schemes.” – The Economist

A recent discussion spawned the idea of implementing a carbon tax within DC, and so I wrote up this brief.

What and whom would a carbon tax affect?
A carbon tax, technically a tax upon the carbon content of energy and fuels, would primarily affect electric generation, gasoline & diesel, and heating fuels (natural gas, fuel oil). A narrower tax could affect only fuels, or electricity. The UK’s carbon tax, for instance, taxes various energy sources at differing rates.

Who consumes energy in D.C., and how?
The EIA reports that DC’s total energy consumption is 70.5% imported electricity, 18.7% natural gas, 7.9% gasoline, and 2.7%fuel oil. 66.3% of energy is consumed by the commercial sector (i.e., offices), 19.9% by residences, 12.1% by transportation (i.e., cars & trucks), and 1.6% by industry.

Of carbon emissions within DC proper in 2010, natural gas was 54.6% and petroleum 45.2%. Because DC imports all of its electricity, it has the least carbon intense economy among the states, emitting 91.6% less CO2 per dollar of GDP than the US average. This does not, however, include fuel burned for electricity used by DC end users; 59.2% of DC electricity originated from fossil fuel generators.

Have carbon taxes been implemented elsewhere?
Yes, several jurisdictions have. Finland and Sweden were first, in 1990 and 1991. In North America, the provinces of British Columbia and Quebec have carbon taxes, as does the city of Boulder (on electricity only). Dozens of multinational corporations, including most oil majors, use an “internal carbon price” to evaluate corporate decisions: ExxonMobil’s is $60/ton.

How have these fared?
British Columbia’s carbon tax, unique in its broad reach even though the province works within the framework of a high-carbon-emitting country, “has been remarkably effective in reducing fuel use, with no apparent adverse impact on the province’s economy,” according to a University of Ottawa study. GDP growth paralleled Canada’s, income tax rates fell to the lowest nationwide, and fuel consumption fell by 17.4% per capita.

Have carbon taxes been proposed in U.S. states?
A bill has been introduced in the Massachusetts legislature, and a ballot measure is currently collecting signatures. In Washington state, Governor Jay Inslee has specifically directed a legislative commission to study a carbon tax, and an NGO has proposed draft legislation.

What level of tax would be appropriate?
An easy guideline for measuring the impact of a carbon tax is that a tax of $1 per ton of CO2 results in just less than 1¢ in tax per gallon of gasoline. DC’s current gas tax rate of 23.5¢ per gallon thus implies a tax rate of $27.98/ton of carbon dioxide. (Maryland’s gas tax is now 32.10¢ per gallon.) This rate is very similar to the C$30/ton that British Columbia charges, and near the midpoint of the $5-65/ton “social cost of carbon” price suggested by the White House.

Where do proceeds of carbon taxes go?
In most cases, as in British Columbia, carbon taxes are a “tax swap,” whereby other taxes — notably on income, capital, etc. — are reduced. Some bills, like that proposed by Citizens Climate Lobby, feature a “dividend,” or direct rebate back to taxpayers. Sometimes, climate actions are funded with a portion of proceeds as well; the Massachusetts bill, for instance, directs $90 million in revenue towards transportation debts and 10% to clean energy. In DC, ambitious plans have been launched, but not yet funded, for transit expansion (by WMATA and DC) and for cutting emissions, and a carbon tax would be one way of funding implementation of those plans. (Boulder’s tax was implemented to fund its climate action plan.) In addition, DC currently pays its annual operating subsidies for both WMATA ($275 million in FY2014: $58M bus, $42M rail, $22M paratransit) and DDOT transit out of general funds, and a carbon tax could be a stable, dedicated source of transit operating funds.

Who are winners and losers?
A carbon tax that includes electricity would have a much broader base and thus wider impact. It would primarily affect the office sector, and as such mostly commuters, but it might also attract Congressional attention. A carbon tax solely on fuels would mostly impact building heating/cooling; again, this would largely fall on offices, but also on DC residents’ heating bills.

Although a carbon tax typically is somewhat regressive, there are many ways to design a carbon tax to mitigate impacts on lower income consumers. In particular, a DC carbon tax could use targeted measures to offset higher home heating costs for low income residents: income tax credits, weatherization or LIHEAP assistance, and transit improvements.

Further reading
Sightline Institute: Carbon Tax Fact Sheet
Resources for the Future: Carbon Tax FAQs
Citizens Climate Lobby: DC Chapter

The Silk Road’s detour to the Washington Channel

The first post in the watershed series mentioned that Morus alba (white mulberry) is a common invasive understory tree found at the edges of lawns along the Washington Channel, particularly along the unmown verge beside the fences that ring East Potomac Park’s recreation facilities. Given a chance, these shrubs will grow into a smallish tree of up to 15 meters, with a peculiar combination of lobed leaves on young shoots and heart-shaped leaves on older shoots. Its copious blackberry-looking fruits , which can disperse an estimated 20 million seeds per tree, make a convenient food source for birds and maybe humans — or else they leave a sticky purple mess on the walkways below.

But wait, mulberry? Isn’t that what silk is made from? How did that end up here?

White mulberry
What is this weed, and what does it have to do with the Opium Wars, Jefferson family wedding gowns, and deforestation in Ontario?

Silk production, or sericulture, was invented in China at least 4,000 years ago; legend says it was discovered by a princess who was strolling through the woods with a cup of hot tea. Young mulberry leaves are fed to silkworms, which spin silk threads around their cocoon as they metamorphose into moths. The cocoons are collected, boiled, and the threads are spun into fiber. China still accounts for most of the almost one million hectares (2.5 million acres) of mulberry under cultivation worldwide, according to the FAO, largely for silk but also for forage, wood, and even biofuel.

Yet sericulture (silk cultivation) requires that both mulberries and silkworms thrive in tandem. Mulberries obviously have adapted well enough to the local climate; thousands of years of domestication has selected for robust and easily grown varieties. The silkworms are a different story: they’ve been raised indoors for thousands of years, and thus have evolved into a very narrow ecosystem — they don’t even survive in the wild anymore, and require an exacting temperature range of 73-84° F, with high humidities, in order to thrive.

Silk was long one of the world’s most coveted agricultural products, and for centuries the world went to astonishing lengths to procure it from China.* Starting all the way back in Jamestown, Virginians attempted to get a cut of this lucrative trade by manufacturing silk: it seemed an ideal fit for the area’s warm climate and then-remote location, and potentially valuable both for the colonists and for British weavers. Yet while Virginia hews a bit closer to such temperatures than England, it isn’t exactly a room-temperature silkworm paradise. So while the robust mulberry thrived, fragile silkworms brought to Virginia didn’t, and instead Virginians profited off the native tobacco plant.

Mulberry Row

Thomas Jefferson’s family attempted silk cultivation at Monticello, and the results are telling. Above is “Mulberry Row,” the remnant of a lane lined with mulberry trees and, once upon a time, several buildings where slaves and other laborers did much of the work of the plantation. Obviously, the mulberry trees have done okay over the years — outlasting the buildings, for instance. The silkworms, though? Not so much. In 1811, Jefferson jokingly wrote to his granddaughter Cornelia,

your family of silk worms is reduced to a single individual that is now spinning his broach. to encourage Virginia and Mary to take care of it, I tell them that as soon as they can get wedding gowns from this spinner they shall be married. I propose the same to you that, in order to hasten it’s work, you may hasten home; for we all wish much to see you.

For what it’s worth, neither Mary nor Cornelia ever married, although I doubt her silkworm colony’s failure to generate enough silk for a wedding gown had much to do with that.

Silk was so valuable that Americans couldn’t be dissuaded by the industry’s failure in Virginia. Silkworms, as mentioned above, are fickle and highly adapted to the methods of Chinese sericulture; they feed almost exclusively on Morus alba, which as mentioned grows quite vigorously on Chinese farms. Eastern North America has a native variety of mulberry, Morus rubra, an understory plant suited to the area’s deep forests, but the silkworms rejected M. rubra feed.

Instead, colonists planted several Chinese mulberry varieties in hopes of keeping their silkworms happy. Colonial-era botanist William Bartram, in his travels through the South, noted dozens of instances of M. rubra but only one of M. alba trees — at a plantation near Beaufort, S.C. that was attempting sericulture (digitized book, pg. 308; location surmised between present-day Jacksonboro, S.C. and Savannah, Ga.). Later, Connecticut implemented various subsidy schemes, even including a cash bounty on planting Chinese mulberry varieties, and eventually succeeded at building a small silk industry in the 19th century.** (The Morus multicaulis mentioned in the Mansfield article is now recognized as a variety of M. alba.)

In the intervening centuries, the invasive M. alba has far outcompeted native M. rubra on its home turf: M. alba has spread much of the contiguous United States except for the desert Southwest, high plains, and taiga forest, and pushed M. rubra to endangerment in Connecticut, Massachusetts, and Ontario. Not only have widespread planting efforts like those in Connecticut spread M. alba far and wide, but it’s a tree that’s been honed by centuries of breeding for vigor, with a “high growth rate and great adaptability to adverse environments,” according to the Global Invasive Species Database: “M. alba and hybrids were evaluated to be consistently more fit than the native M. rubra in a laboratory study.” M. alba hybridizes with, and spreads root diseases, to M. rubra. Widespread deforestation and urbanization in eastern North America opened up countless opportunities for sun-loving, early-successional species like M. alba, while concomitantly destroying the deep shade that M. rubra adapted to.

* As a descendant of Cantonese merchants, perhaps I should be glad that these experiments failed? Oh, the complicated webs that history weaves for us!
** The mild success found in Connecticut indicates that perhaps it was less the climate, but Virginia’s lack of capital for indoor silkworm warms, that doomed the early industry.

This semester, I’m taking a Natural Resources class through Virginia Tech about understanding local watersheds, wherein I’ll be researching and posting knowledge about the Washington Channel. You can explore the other watersheds that my classmates are investigating over at the class blog’s page. Other posts in this series can be found using the tag watershed.

Washington Channel: more a conduit than a stream

While Washington Channel is known for its fishing, it’s not because it’s a particularly inviting habitat for fish species. Instead, its unique flow pattern of imported water make it a “trap” for fish swept upriver by the tides, and as such it sees fish species that aren’t typically found in other local waters — which, oddly, makes it popular among anglers.

Washington Channel & Tidal Basin at high tide

The most productive and diverse habitat in most waterways–the shorelines–are along the Washington Channel entirely armored with concrete. Beyond those concrete walls are monocultures — either more concrete or lawns, rather than on-shore wetlands. Between the walls, the constant scouring effect of the Channel’s twice-daily flush keeps the Channel relatively deep, so there are scant near-shore wetlands: the central channel is kept at least 9-14 feet deep for navigation purposes, but the entire channel ranges from 3-26′ deep. (The Tidal Basin is a bit more inviting to life, since it’s shallow [5-7′ throughout, average depth of 6.5 ft.] and a bit more placid.) The shallow-water ecosystems at the water’s edge, which combine sunlight, warmth, nutrients, and shelter, are largely absent along both. The Channel is, in effect, a concrete canyon.

DC Fire Rescue Boat and Army War College

This canyon isn’t very resilient, either; it can easily flood, as there’s nowhere for water to go when the river rises — or even for the wake from powerboats to do anything other than echo off the walls.

Washington Channel & Tidal Basin at high tide

The shore edge’s armor has started to degrade, though: a combination of higher water levels, subsidence by the marshy soil, inevitable concrete failure, and erosion means that some areas behind the seawall are now almost permanently wet. Some wetland species might start to colonize these damp pockets, although lawnmowers will probably thwart their progress.

Some of the shallower parts of the Washington Channel have demonstrated potential as rich habitat, though. A stretch of older seawall along Fort McNair, beginning in a small lee behind the Titanic Memorial, is a comparative haven for aquatic vegetation and fish. At one point, there was a 10-20′ wide band of submerged aquatic vegetation (SAV) off the fort’s shore — which, according to the NOAA navigation charts, is the shallowest part of the Channel at just 2-5′ deep. These underwater meadows provide valuable fish habitat, particularly for anadromous (half-ocean, half-estuary) species that spawn there before returning to the saltwater estuary downstream.

Even as Potomac River water quality has improved, habitat quality in Washington Channel remains poor. The quantity of SAV (much of it invasive hydrilla, which was still better than nothing) grew substantially in the 1990s, alongside large fish populations.

ecosystem health Wash Channel

Sadly, major rains throughout 2003 — when the Potomac carried more than 3X as much water as in the drier years 1999-2002, and twice its annual average (MWCOG/VT PDF, pg. 32-33*) — led to severe sediment and nutrient overload throughout the Potomac ecosystem, and thus to large algae blooms in 2004. These two years’ trials devastated established SAV in the upper Potomac estuary, including in Washington Channel, and so far neither plant nor animal life seems to have recovered.

Second chances: improving habitat in channelized waterways

While the Washington Channel may be the local champion for having the least natural stream banks, it’s sadly far from the only such watershed nationally. Perhaps the worst example of an “imprisoned river” is the Los Angeles River, almost all of whose banks were paved back in 1938.

Yet nature does abhor a vacuum, and so if you provide adequate habitat (as the Channel did for those few lovely years around 2000), an ecosystem will soon blossom. In Chicago, the Friends of the Chicago River built a “floating fish hotel” to provide a smidgen of near-shore-wetland habitat within downtown’s urban canyon, and plans to significantly expand upon this experiment in the near future.

* Incidentally, to update something I wrote earlier about Western and Eastern water systems, the Colorado River’s pre-diversion annual flow was 50% larger than the Potomac’s average flow (at Little Falls) today. It would rank among the largest Eastern rivers, like the Hudson or Susquehanna. This great map from the Pacific Institute clearly shows my earlier point: the East is well-watered indeed.

** 2018 update: a SAV planting program has succeeded in dramatically increasing SAV in the upper Potomac estuary since 2013, and in increasing juvenile bass populations. Floating “fish hotels” have been added next to the 7th St. “recreation” pier at the Wharf.

This semester, I’m taking a Natural Resources class through Virginia Tech about understanding local watersheds, wherein I’ll be researching and posting knowledge about the Washington Channel. You can explore the other watersheds that my classmates are investigating over at the class blog’s page. Other posts in this series can be found using the tag watershed.

Fresh policies will freshen the flow into the Washington Channel

Yesterday, I wrote about the numerous storm drains that currently dump polluted water directly into Washington Channel. The District of Columbia recently adopted some of the nation’s most stringent and innovative rainwater policies, and the Washington Channel watershed stands to significantly benefit as plans and projects adapt to these new policies and incorporate state-of-the-art practices in green infrastructure (GI). The Natural Resources Defense Council’s “Rooftops to Rivers” report give DC’s new policies a high rank (just behind Philadelphia) among their “Emerald City Criteria” for river-friendly municipal policies.

Canal Park's fountain & rain garden
The new Washington Canal Park, just a few blocks east of the Washington Channel watershed, recycles stormwater not just for its site but also for three neighboring developments.

The impetus for these changes came from the 2011 renewal of DC’s “MS4 permit,” the EPA permit for the storm drains that drain the urbanized part of the Washington Channel watershed (and 2/3 of the District), and is managed by the District Department of Environment (DDOE). As part of this process, DC has adopted a completely new set of stormwater regulations with three key innovations:

  • a DDOE impervious surface charge to generate revenue for municipal green infrastructure, encourage existing buildings to reduce impervious cover, and reward “RiverSmart” properties (this is separate from DC Water’s impervious surface charge)
  • a retention standard that requires new buildings to retain 1.2″ of rainfall on site (~90% of all rain events), and renovations to retain 0.8″ on site
  • a credit trading scheme, the first in the country, giving the retention standard flexibility for dense downtown developments, rewarding efforts that go beyond, and generating funds for comparatively inexpensive GI improvements in the neighborhoods like Canal Park. By taxing bad things, like water pollution, you create an economic incentive to create good things, like neighborhood parks. (In DC, this creates a tidy way to “tax” federal offices through utility fees, and then build neighborhood parks.)

Although DDOE expects only 1% of the city to annually be affected by the retention mandate, that’s still 10X the area currently affected each year by voluntary green infrastructure efforts.

While this change in stormwater regulations is currently only tied to the separated storm drain permit managed by DDOE, DC Water hopes that these efforts will be able to have an appreciable impact on its troublesome combined sewer system. If so, DC Water may be able to renegotiate an existing EPA mandate requiring billions of dollars in new “deep tunnel” pipes (see pg. 7 of this Brookings report).

These just-implemented policy changes are already shaping up to have a positive impact on the Washington Channel watershed, where much of the urban fabric will change in coming years.

  • The Southwest EcoDistrict, a plan currently under development (primarily by the federal National Capital Planning Commission, with ZGF Architects) for the redevelopment of several blocks of mostly federal offices centered around 10th & D Streets SW, plans a truly cutting-edge water management scheme. The overarching goal is to reduce water use by 70% even while increasing the number of people on the site. Pages 11-29 of the May 2013 PowerPoint featured on their website goes into great detail about the strategies that the EcoDistrict can employ towards that goal: treating both greywater and air conditioning condensate water for potable use, storing a 1.7″ rain event in a truly vast cistern hidden underneath an existing bridge, and (by going beyond the 1.2″ mandate) receiving stormwater credits from other developments.
  • Over half of the Washington Channel’s urban frontage (over six blocks) is included within plans for the Wharf, a proposal to completely transform the Channel’s shoreline. The development embraces the Channel with a new riverwalk and several public piers that will bring the public down to the Channel’s water — very different than today’s gated-marina frontage. Complying with DC’s 1.2″ retention standard earns the Wharf the maximum number of LEED-ND points possible under the stormwater management credit, helping it achieve its LEED-ND Gold rating. Among the innovative strategies planned: using stormwater as process water within an on-site combined heat & power (cogeneration) facility that improves both energy efficiency and reliability.
  • Recent construction underneath the National Mall, part of which is within the Tidal Basin watershed, not only rebuilt the severely compacted turf but also included 500,000 gallons of rainwater storage in two cisterns — probably the city’s largest such installation. The Park Service plans another two cisterns as part of further Mall turf renovation, to store water running off the Mall (no, compacted turf doesn’t really do a great job of absorbing rain) and its drives for future irrigation uses. These cisterns could be just the start: in 2011, NCPC studied a two-block-long cistern, the entire width of the Mall, to store 20,000,000 gallons — enough to handle a 100-year rain event, and hopefully prevent the Federal Triangle from flooding again.
  • Stormwater fees are also having an impact on a smaller scale. My own apartment building near the Washington Channel, built during the concrete-happy 1960s, has just embarked upon an aggressive program to replace paved surfaces — open roof, impermeable walkways and driveways — with green or permeable surfaces. This long-overdue plan was put into motion due to the new impervious surface charge.

In the future, big storms like tonight’s (but not quite so big) might actually improve the Washington Channel’s water quality, instead of harm it. Later: a look at the Washington Channel’s water chemistry, plus what that means for future evaluation of the channel. But tomorrow, I’ll look at how the physical form of the Channel shapes habitats along, and within it.

This semester, I’m taking a Natural Resources class through Virginia Tech about understanding local watersheds, wherein I’ll be researching and posting knowledge about the Washington Channel. You can explore the other watersheds that my classmates are investigating over at the class blog’s page. Other posts in this series can be found using the tag watershed.

The rain falls upon this plain, but then what?

Washington Monument in a different reflecting pool

As I mentioned in previous posts, the Washington Channel is quite unique in that the water contained within it has little to do with its drainage basin: instead, its water is essentially imported from downstream via the tidal cycle. As such, its water quality (unlike almost all other waterways) largely does not reflect the land and water context adjacent to it. In addition, the Channel benefits from being entirely within the District of Columbia: the federal government has long held title over the waters (Morris vs. United States), and used parkland to create and frame the Basin and Channel. As a result of that unique context, not only does parkland surround all of the Tidal Basin and most of the Washington Channel, but the surface waters are also under federal protection.

Tidal Basin & Washington Channel hydrological maps

The Tidal Basin and Washington Channel do receive surface and groundwater runoff from their immediate areas, which together add up to 1.412 square miles of the District. The Tidal Basin drains 0.423 sq. mi., of which 0.169 sq. mi. (almost 40%) is surface water. 43% of the watershed is parklands and grass areas, including parts of the National Mall, the monuments ringing the Basin, and even the small hill underneath the Washington Monument.

Tidal Basin & Washington Channel hydrological maps

The Washington Channel drains 0.989 sq. mi., of which 0.3 sq. mi. (25%) is surface water. As its north bank is heavily developed, 53% of its watershed includes urban development, and the remaining 22% is parkland.

DC’s largest water pollution problem is its combined sewer/stormwater system, or “CSO.” (I’ll write more on these systems in later posts; they’re super-important for understanding urban water quality but not entirely relevant to this post.) This system, which is responsible for dumping a toxic brew of sewage and rainwater directly into many local waterways, drains one-third of the city, including most areas built before World War 2. However, since the immediate environs of the Tidal Basin and Washington Channel were redeveloped in a somewhat recent era, they have separate sewer and stormwater systems. This map shows the large parts of the city which have combined sewers — many of which, incidentally, are named after the creeks that they replaced:

Instead, smaller, separated storm drain systems — nine along the Channel and three along the Basin, delineated by the faint lines running roughly perpendicular to the water on the map below — intercept rainwater that falls on Southwest Washington’s roofs and streets, and dumps that untreated water into either the Tidal Basin (light blue on this map) or the Washington Channel (tan on this map):

Tidal Basin & Washington Channel hydrological maps

As you can see by comparing the first and last maps, the inland boundaries of the two watersheds are defined by these artificial drainages rather than the natural contour lines seen in the first map. If you look in the vicinity of N and O Streets SW, for instance, you’ll see that there’s a valley roughly between Third Street and Half Street. Historic maps show this as what was James Creek, which drained pretty much due south to the Anacostia River, but instead these blocks now drain “uphill” to the Potomac to the west.

The storm drains dump unfiltered water, often contaminated with urban pollutants, directly into the Basin and Channel. This contributes substantially to the substantial water quality problems within these two water bodies, but plans are underway to substantially reduce the quantity of these flows in the near future.

Sources for this post, notably the maps and geographic analysis of watersheds, include the DC Department of Environment’s water quality standards documents, which I’ll report on in greater detail in an upcoming post.

This semester, I’m taking a Natural Resources class through Virginia Tech about understanding local watersheds, wherein I’ll be researching and posting knowledge about the Washington Channel. You can explore the other watersheds that my classmates are investigating over at the class blog’s page. Other posts in this series can be found using the tag watershed.

Going with the flow: how Washington Channel’s mechanics impact its relative water quality

This semester, I’m taking a Natural Resources class through Virginia Tech about understanding local watersheds, wherein I’ll be researching and posting knowledge about the Washington Channel. You can explore the other watersheds that my classmates are investigating over at the class blog’s page.

In this installment, I’ll take a closer look at how the channel functions today, and what that means for its water quality. Other posts can be found using the tag watershed.

Last week, I examined how the silty Potomac started to clog the harbors around Washington, and mentioned how that resulted in the 1896 construction of the Tidal Basin and the Washington Channel. Today, we’ll investigate in some more detail just how the basin and channel work.

The satellite photo currently shown on Bing Maps appears to have been taken at low tide, when the Potomac River flows more or less as it always has, carrying fresh water east to the Chesapeake Bay and Atlantic Ocean:

Washington Channel: low tide

Note the high sediment levels in the Potomac, as indicated by its brownish color — it appears to carry more sediment than the Anacostia. I’ve highlighted the rivers’ silty water flows with greenish arrows.

At high tide, the picture looks very different, as the silty rivers collide with waves of clearer, darker ocean water racing upriver:

Washington Channel: high tide

The Tidal Basin-Washington Channel system uses the tidal surge to activate a pair of one-way gates. Imagine the Tidal Basin as being bound by two sets of doors that both only open inwards. The first set, the Potomac inlet gate, is at the Basin’s southern end: facing the flow of tidal water but perpendicular to the river’s flow. When the tide rises, the pressure of water flowing upstream pushes open the inlet gate, filling the relatively low basin with 250 million gallons of water:

Washington Channel & Tidal Basin at high tide

When low tide occurs, water recedes away from the Tidal Basin at the Potomac gate. The now-higher water in the basin tries to escape back out to the Potomac, but because those gates only open inwards, the water instead pushes the gates shut. (Water only pushes, not pulls.)

Meanwhile, at the Tidal Basin’s eastern end, an outlet gate leads to the Washington Channel. There, the gates open from the Basin to the Channel: they’re pushed open when the tide falls away from the Basin, spilling those 250 million gallons into the Channel, and they’re pushed shut when the tide rises.

Since the Channel is scoured during both the high and low tides, and is fed by the clearer tides and not by the muddy Potomac, sedimentation is no longer a problem and the channel retains navigable depth without the need for dredging. And since the Tidal Basin is fed by the tides — it’s always “high tide” in the Channel — the water within Washington Channel more closely resembles that of the Chesapeake Bay than the Potomac River next door. Thus its water is relatively clean, which is curious for a water body within the District of Columbia.

As a habitat, the Channel more closely resembles the brackish downstream Potomac than any of the neighboring freshwater rivers and streams. Fishermen know this, and set up along its banks to catch fish that have been swept upstream by the tide:

Washington Channel & Tidal Basin at high tide

In further installments, I’ll take a closer look at the shorelines, adjacent land use context, drainage, and water quality measures within the Channel.

Mud becomes concrete: Washington Channel’s history, told through maps

This semester, I’m taking a Natural Resources class through Virginia Tech about understanding local watersheds, wherein I’ll be researching and posting knowledge about the Washington Channel. You can explore the other watersheds that my classmates are investigating over at the class blog’s page.

In this installment, I’ll take a closer look at how the channel came to be a (sort of) discrete watercourse, to provide some context for later posts about today’s land and water quality. Other posts can be found using the tag watershed.

From Montreal to Providence to Trenton to Richmond, many of the East Coast’s great cities arose astride the “fall line,” an imaginary line along which its many rivers tumble from shallow rapids in the hills to slow, wide, sometimes brackish coastal estuaries. In an ocean-going era, such a location ensured easy access for oceangoing commercial boats, fresh river water, produce from farms upriver and fisheries downriver, and later to water power from the rapids or waterfalls alongside — all without the considerable downside of a coastal location’s vulnerability to frequent Atlantic storms.

[Minneapolis, built astride the falls of the Mississippi, could be considered the most interior of the East Coast’s fall line cities.]

Washington, D.C. is among these fall line cities, and its constant attempts to reshape the Potomac River’s banks also show the vulnerabilities that fall line geology also brings. Above Washington, the Potomac speeds through a narrow gorge, tumbling over its majestic Great Falls and past the high bluffs of wealthy towns like McLean, Potomac, and Georgetown. At Washington, three flows of water conjoin: the slower and broader Potomac, Atlantic seawater that tides pull all the way up the Chesapeake Bay and the Potomac estuary (with tides rising to 3.5′), and several surface flows. The comparatively flat topography of the L’Enfant City results from it resting upon a “shelf” of sediment brought there by the Potomac over time. This 1861 bird’s-eye view map by John Bachmann (from the Boston Public Library collection) plays up the topography, dramatically showing how the character of the Potomac valley changes at Washington:

Bird's eye view of part of Maryland, Distr of Columbia and part of Virginia

Several surface flows join the Potomac at Washington, notably the Anacostia River, Rock Creek, and Four Mile Run, but also several streams that have since been buried like Tiber Creek and James Creek. (David Ramos has compiled an impressive map of these buried streams.) From the very beginning of the city in 1790, plans were made to tame these streams for human uses like shipping. A map from the 1790s, drawn by John Russell, shows how city fathers, Pierre L’Enfant among them, conceived a system of drainage improvements. These canals were straightened channels based upon the east-west Tiber Creek and the north-south James Creek, both arising roughly where Garfield Park is today at the foot of the Capitol. The map also shows the outlines of the deeper, more easily navigable channels within the mostly shallow Potomac:

Plan of the city of Washington[...]

This idealized 1852 view, published by E. Sachse, illustrates the canals in an improbable shade of blue:

Shortly after Washington was founded, the Potomac’s plentiful sediment became a problem for the growing city. Land clearance for forestry and farming upriver combined with increasing levels of urban pollution dumped into local surface waters, making the water noxiously polluted — particularly during low tide, when pollution festered in exposed tidal marshes. The insalubrious tidal marshes at the mouth of Tiber Creek, beginning at the foot of the White House, appear to have given rise to the widespread myth that “Washington was built on a swamp.” The marshes are visible in these digital reconstructions of the 1791 shoreline:

Then and now: Washington Channel

Original and present shorelines of Potomac Park

The sediment buildup also threatened the city’s access to maritime trade. Given the marshes along the Tiber, the new city’s only shoreline adjacent to a deepwater channel within the Potomac was along its southwest waterfront. Wharves sprang up along Maine Ave. SW, landing fish and ferries that went to Alexandria and points beyond. In this process, this shore gradually urbanized and gained a “coat of armor” as buildings crept up to the water’s edge, as shown in this 1883 drawing by A. Sachse:

Private property owners’ interventions to shape the shoreline would soon be dwarfed by Congressional plans, particularly as the sediment threatened the relatively deep channel fronting Southwest’s wharves. Engineers (notably Peter Conover Hains) from what would become the Army Corps saw an opportunity to tame the city’s shoreline, preventing severe floods like that of 1881 from reaching the city’s core. Meanwhile, planners saw the potential for new parks — simultaneously adding land to the capital of a fast-industrializing country, meeting a post-Civil War national zeal for commemorative monuments, and providing Washington with a vast expanse of parks at its doorstep (as the fin-de-siecle era’s vogue the City Beautiful demanded).

This 1888 map by E. Kurtz Johnson depicts an early “cloverleaf” plan by Hains for filling in much of the Tidal Basin area, leaving a series of small pools that would be used to flush a new Washington Channel downstream:

In 1901, the City Beautiful reached its apogee here in Washington with the McMillan Plan. Shortly thereafter, the canonical birds-eye view of Washington had shifted 270 degrees; instead of placing the Capitol dome front and center with the filthy Potomac River in the distance, now bird’s-eye views proudly showed off the carefully sculpted shoreline, with its large and scenic Tidal Basin, an urban shoreline for the Washington Channel, and probably many more trees in Potomac Park than existed at the time (1916, drawn by H. H. Green):

Many of these maps courtesy of the Historic Print & Map Company, via DC Vote’s archive of Washington, DC, Historical Maps; high-res PDF versions can be downloaded there. Others were drawn from a Washington Post Magazine feature by Scott W. Berg, featuring mapping work done by architect Don Hawkins and Dan Bailey/UMBC Imaging Research Center.

Updated 17 May 2015 to fix broken links. The USGS recently made turn-of-the-century maps of DC available (the 1:62,000 scale is best); most show the Channel’s “final” boundaries, but are useful for observing urban growth and other topographical features.

Washington Channel’s trees and shrubs: a tale of two monocultures

This semester, I’m taking a Natural Resources class through Virginia Tech about understanding local watersheds, wherein I’ll be researching and posting knowledge about the Washington Channel. You can explore the other watersheds that my classmates are investigating over at the class blog’s page.

In this installment, I’ll take a closer look at the woody plants found along the channel. Other posts can be found using the tag watershed.

By and large, the plant life along Washington Channel is a tale of two monocultures. Its filled-in banks long ago had their native species removed; instead, people have planted two species in abundance: ornamental cherries in East Potomac Park on its west bank, and willow oaks on the circa-1970 Waterfront Park on the east bank. The effect of having so many identical trees might be unnatural but can be enchanting, certainly in the early spring when the world-famous cherries bloom:

Cherry Blossom Trees

And also in the autumn when the willow oaks turn gold:

Waterfront Park

The large shade trees planted here often were chosen to tolerate the damp, mucky landfill soil; some were chosen for ornamental fall color, as well.

  • Willow oak [Quercus phellos], as mentioned above, was planted along walkways and streets throughout Southwest Waterfront. Some have grown to ~80′ tall.
  • Scarlet oak [Quercus coccinea] is also found along streets.
  • Sugar maple [Acer saccharum] was planted along streets and in landscapes, perhaps for fall color.
  • River birch [Betula nigra] grows in a few clusters in East Potomac Park [photo].
  • Baldcypress [Taxodium distichum], a deciduous conifer common in bayous, has recently been planted near the golf course [photo].
  • Black willow [Salix nigra] is one of the taller trees along the channel [photo].
  • Swamp cottonwood [Populus heterophylla] also thrives along the west bank [photo].
  • Honeylocust [Gleditsia triacanthos] is a common urban street tree, since it permits dappled sunlight below.
  • American sycamore is another sturdy tree common to streets and parks.
  • Zelkova [Zelkova serrata] is another common street tree.
  • Eastern white pine [Pinus strobus] appears to be one of a few evergreens planted in East Potomac Park [photo].

As an intentional urban landscape lined with grassy or paved open spaces, smaller ornamental trees are more plentiful along the Channel.

Several urban weeds are also common along the Channel, notably white mulberry [Morus alba] and tree of heaven [Ailanthus altissima] [photo].

Plans for redevelopment of the Channel’s east bank, roughly between 6th and 12th St., call for a greater variety of mostly North American shade trees to replace the willow oaks. These include Kentucky coffeetree [Gymnocladus dioicus], honeylocust, tulip tree [Liriodendron tulipifera], blackgum [Nyssa sylvatica], swamp white oak [Quercus bicolor], and Chinese elm [Ulmus parvifolia].

July shorts: aimless bicyclists, green roofs

Pearl St.
Do the French have a term for aimlessly bicycling around towns?

Cleaning out the fridge, so to speak, with several links & quotes:

1. Flaneur, randonneur: just wandering about, whether on foot in the city or on bike in the countryside, is a long-established practice in French but just doesn’t translate to English.

There’s no direct translation for randonnée (pronounced ran-don-NAY) — it can mean a long outing or trip, or a ramble in the countryside. For its practitioners, called randonneurs, it’s easier to define the event by what it isn’t: a race. There are time limits, which means riders can’t go too slowly — but they also can’t go too quickly.

2. Mayor Bloomberg speaking about the myth of the scofflaw cyclist at Citibike’s launch:

I’m sure there will be people who will, just like they are today, take their bicycles and do things that break the law. This will shock you but there are even people in automobiles who do the same thing. When you take a look at the number of people killed in automobiles, it sort of dwarfs everything put together on the road.

3. The world is filled with ironic NIMBYs, but this story still takes the cake: a retired Concorde pilot complaining about the noise from a playground.

4. Nate Berg sounded an appropriate note of skepticism over green roof cheerleading. It always really irked me that Mayor Daley would take credit for putting green roofs on big box stores in Chicago, even though the ratio of blacktop parking lot to green roof built by said stores is easily 3:1. A garden built on the ground, within a depaved parking lot, can offer more environmental benefits than a monocultural, thin green roof, and at a much lower cost. Oh, sure, someone might lose their parking space, but discouraging driving is yet another environmental benefit!

5. During the years I bike commuted through the South Side, it always fascinated me that Chicago’s ghettos were often bereft of any commerce whatsoever: for the most part, there weren’t even fast-food joints along the way, even though plenty of people lived nearby. Other U.S. cities (much less thriving Canadian inner cities) didn’t seem quite as derelict: witness the busy, if run-down, retail streets of Spike Lee’s Brooklyn. Whet Moser uncovers research by Marco Luis Small that quantifies this: “In some cases, the difference is stark. Chicago has 82% fewer small restaurants, 95% fewer small banks, and 72% fewer small convenience stores than a black poor ghetto in the average city.”

Wider fronts in the not-war on cars: the East Coast & the world

More data points that I’d meant to post in last week’s update from the trenches:

1. Doug Short has graphs of population-adjusted VMT going back to 1971. Interestingly, most of the decades seem to see pretty steady growth, with growth rates (relative to 1971, so not even accounting for the larger base) declining in the 1990s, leveling off in the early 2000s, and beginning a sharp decline thereafter. The cumulative effect of that curve? Americans drive about half as many miles as would have been projected in the late 1980s, based on the fast-growing trend line at that time. Time to shred all those old highway plans, folks! (Via Brad Plumer‘s latest post on VMT trends)

2. A bunch of papers and videos from the OECD on driving trends in the USA, France, Netherlands, Mexico, Japan, and Australia. (Also via Plumer.)

3. “Gasoline demand stayed flat in states bordering the Gulf of Mexico or in the Rockies. But on the East Coast, it has slipped 10% below its peak level…. it has accounted for half the overall drop since the [peak]… The more striking trend: East Coasters are simply driving less. Vehicle miles traveled in Northeast and South Atlantic states in the year ended in March were 4.2% lower than in the same period ended in September 2007. In the rest of the U.S., they are down just 0.5%.” — Liam Denning, WSJ

Vehicle mix also factors in: “Real Americans” are 2.62X more likely to buy pickups than us effete eastern elitists, and 11.6% less likely to buy a hybrid car, but I doubt that vehicle mix has changed enough over the past few years to explain the differing outcomes.

4. I took this photo in 2005; it was in 2004 that the VMT trend began to sputter. In 2013, the gas station has closed, and a Tesla dealership opened across the street. So yeah, it’s tough to be in the gas biz these days.

$4/gallon, here we come!

5. Of course, Todd Litman from VTPI is always more comprehensive about this topic than anyone else. Here’s his 30-page take, which he updates frequently.

6. Contrast these data points to the comparatively rosy (for carmakers, and therefore awful for the planet) scenario recently posited in the Economist:

One reason for concern is that half the world’s population now lives in towns and cities, which have only so much space for cars… Young urban residents may also be meeting up less often in person, thanks to social-networking sites that let them keep in touch digitally. So they have less need for a car… In particular, the generation who came of age after 2000, the so-called “millennials”, express a preference for having access to rather than owning cars…

[S]tudies also show a marked rise in the proportion of elderly people with driving licences. Baby-boomers pretty much all learned to drive, and now that they are beginning to retire they expect to continue motoring. The development of assisted driving, followed one day by fully automated cars, will allow them to stay mobile for much longer.

What may be happening in rich countries is a one-off shift in the timing of people’s driving careers, so that they start later but then continue well into old age. This may be no bad thing for carmakers… So it is not clear that declining car ownership among young urbanites will have more than a marginal effect on overall car sales….

All in all, “peak car”—the point at which worldwide demand for cars will stop rising—still seems quite a long way off. In the rich world some of the economic factors that have deterred young people from taking up driving will fade away: as cars become increasingly self-piloting and accident rates fall, insurance costs should decrease, and in time there will be little or no need to take expensive lessons.

Perhaps true, but retirees generally don’t travel very far, and VMT/capita drops off considerably at retirement. Crowded cities in developing Africa, Asia, and Latin America have less potential for car growth, and have arguably embraced many transportation innovations faster than the rich world has.

Parks are free, right?

See those high-rises? They paid for Millennium Park.

And this month’s award for Not Getting the Point goes to:

“The idea that McMillan could be Washington’s Millennium Park or High Line, that kind of creativity has never come to the project,” [John] Salatti [of Bloomingdale] says.

Not only does he want a free park instead of taxpaying development on a decrepit old industrial site that the District needs to develop to meet its own revenue projections. Not only that, but he wants a park on par with two fabulously expensive parks: $475 million and $250 million apiece just for construction, plus ~$9 million a year apiece in maintenance, and all even though his neighborhood is a half-hour stroll from the National Mall, which is not only about as big as Grant Park and Central Park combined, but might have a few world-class attractions of its own. (And yes, in fact, building The Park Of Their Dreams on the unstable structure and soils at the Sand Filtration Plant would in fact cost somewhere in the nine figures.)

No, the real stupidity lies in his ignorance of park financing. Both of those parks were largely paid for by lining said parks with skyscrapers: Millennium Park with revenue from the Central Loop TIF, bolstered by 80-story towers that boast park views, and parking garages underneath it that serve the adjacent downtown; the High Line only became possible by selling its underlying development rights and upzoning some adjacent areas by 50% to permit residential towers in an industrial zone.

It seems especially rich when these NIMBYs lash out in ad hominem attacks that impugn the ethics of anyone (including me) who disagrees with them: obviously, they must be paid off by the greedy developer, since money is apparently the only possible motivation. These folks know something about selfishness: They want city taxpayers to lavish hundreds of millions of dollars to beautify their backyard, in addition to foregoing a considerable opportunity cost from new development.

Climate shorts

I’m on a sporadic publishing schedule this month since finals decided to start arriving earlier, but there’s been a lot of noteworthy things happening on the global warming front:

1. I’d earlier mentioned that a tax swap proposal was actually warmly received by Republicans in at least one poll. A September (pre-Sandy!) update to said poll showed even stronger support:

A majority of Americans say they would vote for a candidate who supports a revenue neutral carbon tax if it created more American jobs in the renewable energy and energy efficiency industries (61% would support such a candidate), decreased pollution by encouraging companies to find less polluting alternatives (58%), or was used to pay down the national debt (52%). A large majority of Americans (88%) say the U.S. should make an effort to reduce global warming, even if it has economic costs.

And, in Mitt Romney (!), there was a candidate who at one point (you never know with that guy) put pen to paper and seemed to like the idea (from his book “No Apologies”):

a tax swap… would encourage energy efficiency across the full array of American businesses and citizens. It would provide industries of all kinds with a predictable outlook for energy costs, allowing them to confidently invest in growth. And profit incentives–rather than government subsidies–would stimulate the development of oil substitutes and carbon-reducing technologies… a tax swap may be the best among the four alternatives currently under consideration…

And Al Gore agrees: “It will be difficult for sure but we can back away from the fiscal cliff and the climate cliff at the same time,” [Gore] said. “One way is with a carbon tax.”

That said, David Roberts discounts the possibility of a carbon tax swap, as does the White House. Oh well.

2. Even if there isn’t a carbon tax in our near future, and even if global warming was hardly mentioned at all during the entire Presidential campaign, Joe Mendelson at NWF notes two more promising takeaways from 2012: Big Fossil’s huge “I’m an Energy Voter” campaign flopped in a huge way, and the year’s numerous weather disasters have perhaps reminded Americans that adapting to climate change will be neither easy nor cheap.

3. Sure, the right-wing spin machine’s anti-empiricism (or, as Noam Scheiber calls it, “intellectual nihilism”) got its just desserts with their embarrassingly wrong election forecasts. However, I doubt that this will have a lasting impact on other important policy topics, notably the climate.

What I worry about is:
(a) the time scale differential between an election prediction (results are splashed across every newspaper within weeks, and a new cycle begins the day after) and a global warming prediction (when the result slowly reveals itself over decades, and is irreversible by then) is like the difference between a cornstalk and a sequoia. With humans’ short attention spans, by the time the former is over and done with, we can still maintain plausible deniability about whether the latter has changed at all.

(b) that the Right has shown little interest in empiricism before — when they’ve been objectively proven wrong, they instead retreat even further into their bubble. We’ve seen it before on, say, supply side economics, where the top marginal rate has fallen by half since 1980 but where (to hear Romney say it) the already-dubious Laffer curve theory is apparently stronger than ever — even though few academic economists agree.
That said, I am really excited about a future in which Nate Silver-esque analytics can help to more broadly inform decision-making from the individual to the national level. All the buzz about “smart cities” is just the beginning.

[Adapted from a comment posted to Grist]

4. A nice quote about said anti-empiricism, by Mark Potok of the SPLC:

“It just seems that on issue after issue after issue we are no longer having disagreements about a certain set of facts. Instead we have two sides presenting absolute alternative realities. And the bottom line, I think, is that from the political right, or the far right, that we are seeing almost nothing but a string of conspiracy theories that have virtually nothing to do with reality. So we cannot even have a rational debate about things that we admittedly disagree about. Instead, we spend our time fending off utterly baseless, fear-mongering conspiracy theories that prevent us moving forward in any way as a society.

“At the turn of the 21st century we are facing very major problems. We are at a time of great social and environmental change and we need to seriously address them — not poison ourselves with the conspiracy theories and baseless fear-mongering that we see today.

5. As if to confirm 3(a) above, I was recently frightened by the documentary “Chasing Ice” (very similar clips are viewable for free at National Geographic). Even though the documentary covers land glaciers, the most dramatic story over the past year has been the collapsing sea ice cap in the Arctic Ocean: ‘experts say that recent data on plummeting ice extent and volume show that the Arctic has entered a “new normal” in which ice decline seems irreversible.’ Over my lifetime, 15,000 cubic kilometers of ice has disappeared from the Arctic Ocean. That’s enough to fill 6,003,910,273 Olympic swimming pools with molten ice!

This kind of change doesn’t just happen in a vacuum. Reshaping the face of the earth on this scale seriously matters. It will permanently shift weather patterns, particularly the jet stream that sets medium-range weather for the Northern Hemisphere, and could be to blame for the very long cold/hot/wet/dry patterns that many of us have seen lately.

6. Curiously, right after I attended the “Do The Math” tour program, none other than the IEA confirmed McKibben’s arithmetic: “No more than one-third of proven reserves of fossil fuels can be consumed prior to 2050 if the world is to achieve the 2 °C goal.”

The world can’t wait for Peak Oil. (I never really liked that too-tidy eschatological scenario, anyhow.) We can’t wait for the fossil age to end by running out of fossil fuels. We will have to will its end, or it will end our age.