There are no mines in New Hampshire that I know of; except surely some aggregate mines and gravel pits? Regardless, the volume I refer you to does not address the impact of mining at all. But I cannot resist bringing this fine volume to your attention: White Paper, River Restoration and Fluvial Geomorphology published in May 2006 by the New Hampshire Department of Environmental Services Department of Transport.

Let me confess an utter fascination with geomorphology as a pure science—I read most anything about it I lay my hands on. So I could not resist this one when it appeared on Google. It is worth reading if only for the clear text, fine illustrations, and sound advice re restoration of disturbed fluvial features. I suspect that anyone involved with mine land reclamation and surface way management at a mine would enjoy this one.

Jumping across the country to Napa County, California and another report on geomorphology with only a slight reference to gravel mining: Channel Geomorphology Assessment: A Component of the Sulphur Creek Watershed, Napa County, California published in 2003 by the Napa County Resource Conservation District. This volume is a fine example of the detail required to quantify the geomorphological characteristics of a single waterway, and to establish the basis for intelligent action that might impact the geomorphology of the waterway, including any mining activity. In this case gravel mining had been undertaken for almost 100 year prior to 1999. The report concludes that the gravel mining probably had not significantly impacted pre-existing conditions, except for increasing the flood capacity of the mined reach. Now that there is no mining, the channel is silting up and flood potential is increasing. I leave you to read the report to get the rest of the potential impact on erosion and fish resources in the watercourse as a function of a dynamic geomorphic area, the upper reaches of which are characterized by many natural landslides that continue to feed large quantities of sediment to the river.

Skipping up the Pacific coast to Washington, I refer you two papers from a journal Washington Geology (vol 26, no2/3, September 1998). The first is Flood Plains, Salmon Habitat, and Gravel Mining by Norman et al. The second (which is in the same e-file on the web) is Reclamation of Flood-Plain Sand and Gravel Pits as Off-Channel Salmon Habitat by Norman. These two very detailed papers provide a wealth of information on the topics noted in the paper titles. Well worth taking a look at if you are interested in geomorphology in general, gravel mining near rivers, and the spawning of fish in areas of such mining.