the osa peninsula

Here is some papers and info on the  impact of gravel mining from stream beds......
For more info on river mining Kondolf from Berkley U did a lot of studies
http://landscape.ced.berkeley.edu/~kondolf/topics/gravel/gravel.html

very good paper
http://www.wdfw.wa.gov/hab/ahg/freshdrg.pdf
another
http://cedb.asce.org/cgi/WWWdisplay.cgi?5015643

In plain talk
http://www.ncriverwatch.org/wordpress/2008/06/07/the-true-cost-of-gravel-min
ing-in-the-russian-river-2/

http://mo.water.usgs.gov/fact_sheets/wtrqual/Gravel/index.htm

And some quotes from some of these sites
from:http://mo.water.usgs.gov/fact_sheets/wtrqual/Gravel/index.htm

ENVIRONMENTAL CONSIDERATIONS

Fish communities are potentially impacted by changes in turbidity and sediment erosion, transport, and deposition. Increased turbidity can affect fish by reducing their feeding efficiency, reducing their tolerance to diseases, and increasing their overall physiological stress. Increased sediment loads also can disrupt fish reproductive success by interfering
with the viability of their eggs and fry (Waters, 1995). Arkansas Game and Fish Commission conducted a short-term study on the Kings River that demonstrated a 50 percent decrease in smallmouth bass downstream from gravel mines because of a 15-fold increase in silt or turbidity. The fine sediments cause smallmouth bass and other sensitive game fish to have poor survival rates because of the smothering of their eggs and fry (Arkansas Game and Fish Commission, written commun., 1997).

Effects on Invertebrate Communities
Benthic invertebrates can suffer significant negative effects from deposited sediments because they are adapted to specific substrate particle sizes. A stream with a diverse substrate size composition will support a diverse benthic invertebrate community. As sediment settles into the interstitial spaces in the streambed, the availability of diverse substrate decreases, resulting in decreased species diversity, abundance, and productivity. A mussel community is especially sensitive to fine sediments and substrate alteration, which can result in a total loss of a species (Parmalee, 1993). Fish communities depend on the benthic invertebrate community as a food source. Healthy fish populations rely on diverse invertebrate communities.
from: http://www.ncriverwatch.org/wordpress/2008/06/07/the-true-cost-of-gravel-minng-in-the-russian-river-2/

Gravel mining is the major cause of induced incision of tributaries as gravel removed from the mainstem is replaced with increased erosion of tributaries causing wildlife, property and structural impacts.

Gravel mining has caused braiding or splitting of the main channel despite the regulations that do not allow gravel mining to upset the rivers form.

Gravel mining has contributed to significant reductions in spawning habitat due to increased turbidity and ensuing embededness of gravels in fine materials that prohibits spawning in many mined sections of the River.

Gravel mining perpetuates a greatly degraded state of the River causing more bank erosion that is followed by bank armoring that increases channelization of the river and causes loss of riparian habitat.

Gravel mining has caused a drop in Middle Reach aquifer levels roughly equivalent to the loss of 450,000 acre feet of water or six and a half times the current SCWA water usage from the river.

These graphics show what has occurred in the Middle Reach of the Russian River between Healdsburg and Forestville, over 25 feet of bed level degradation has lead to a major loss of aquifer storage, it has been calculated to be over a hundred thousand acre feet of water.

Gravel mining continues to threaten our naturally filtered water supplies by reducing the natural bedload transport and perpetuating a greatly incised river channel.

Carving up the Rio Tigre with Heavy Equipment

Destroying One of the Largest Watersheds on the Osa

Yesterday the town of Dos Brazos had confirmation that basically the whole river from the bridge on the main road up to the border of the Reserva Golfo Dulce just outside of Dos Brazos was all in danger of being mined for gravel and rock. Members of the Association of Puerto Jimenez, who came to a meeting in Dos Brazos by invitation, confirmed that not only the town of Puerto Jimenez but 4 other companies were working on getting concessions along the Rio Tigre.  One concession, we believe is already been granted, making a total of 6 concessions each with a possibility of 2km of river to work in. 

These concessions are for mining directly in the river course, using heavy equipment to extract gravel and rock for commercial use.  It will involve channeling the river or making roads on either side as has been demonstrated by the very visible mining going on near the bridge on the main road.  This will destroy one of the biggest rivers on the Peninsula.  A river is a whole unit, what goes on downriver effecting upriver and what goes on up river effecting down river.  Not only will this cause a lot of erosion (the river always needs to replace the gravel taking it from up stream and  from the sides of the river) but it will change the water temperature and flow of the river effecting the fish and shrimp spawning.  The shrimp or crayfish living upstream are the main food source of the river otters. They need to swim down to the gulf to reproduce in brackish water and many fish in the gulf need to come into the rivers or mangrove areas to reproduce.  There will be more silt in the mangrove areas and on the slowly recovering reef that was destroyed by the gold mining. There will be hydraulic leaks and line breakage, contaminating the watershed with harmful chemicals.

We have lived on this river for many years and learned a lot about how rivers work. Rivers are extremely fragile, complicated and difficult to understand.  They are an important part of the whole forest and ocean ecosystem. 

Right now our river has been filled in by sand possibly due to the excessive amounts of gravel being taken out for the road project.  The river is desperately trying to replace what was lost downstream.  There are almost no rocks exposed for fish fry to attach to or for shrimp to hide under during the day.  It is moving with less turbulence increasing the temperature as well.  There have been many studies done in Northern California on the effects of mining gravel in river channels.  Apparently that was cited as one of the main causes of the salmon industries collapse many years ago. If anyone would like, I have copies somewhere of one or two of the studies

Not only will the ecology of the river be destroyed but the lives of the inhabitants both human and wildlife will be effected as well by these proposed concessions.  All the citizens of the Osa need to pay attention and make sure that development does not destroy the peninsula we treasure. 

Liz Jones

Bosque del Rio Tigre