Bloede Dam

Bloede Dam  

Why remove Bloede Dam?

  • Improve public safety (human deaths & injuries have taken place at the dam)
  • Complement upstream restoration work (Union & Simkins dam removal)
  • Improve fish passage (ladder has been unsuccessful & expensive to maintain)
  • Improve stream connectivity for fish and aquatic organisms

Current Progress - Bloede Dam Removal Project

DNR and it's partners have applied for permits for the removal of the Bloede Dam. Work is expected to begin in late fall 2015 to relocate the 12" Bonnie Branch sewer line and the 42" main sewer line. The relocation of these lines will begin an expected 12 month closure of a portion of the Grist Mill Trail, removal of approximately 4 acres of trees behind the dam between the Grist Mill Trail and the Patapsco River, and increased truck and construction activity around Illchester Bridge. ​Work to remove the Bloede Dam is expected to start once this phase is complete - in the fall of 2016. ​Please stay tuned to this website for details on construction work and trail closures. See the links below and to the left for additional details.

​DNR and it's partners are continuing to work with the Maryland Historical Trust to document the historical nature of the Bloede Dam. Informative signage, overlooks on both the Baltimore and Howard County side are among some of the ideas proposed. ​

60% Design Plan Open House was held on January 29, 2015

Key Points:

  • The Bloede Dam will be removed using a passive sediment management approach, releasing up to 312,000 cubic yards of sediment downstream. This is similar to the approach used for Simkins dam, which released about 88,000 cubic yards.
  • Short-term impacts associated with the sediment release could be severe immediately below the dam, with sediment deposits up to 7 feet high.
  • Although there is about twice the amount of sand in the Bloede impoundment compared to the Simkins impoundment, the higher volume of sediment does not result in twice the deposition depths downstream.
  • The river channel behind the dam will recover more quickly. The material behind the dam could be evacuated in 1 to 7 months, while areas downstream may take 6 to 10 years to fully recover.
  • Sections of both the 42” sewer line which runs through the dam, and a 12” sewer line that crosses the river through the reservoir deposit in the Bonnie Branch area will be relocated prior to the dam removal. Once the dam is removed, the sediment will erode and the sewer lines will be compromised if no action is taken.
  • The 42” sewer line will be relocated under the Grist Mill Trail. This means the trail will need to be closed for approximately one year while the work takes place. The trail is expected to be closed from Illchester Road to the dam beginning in winter 2015.
  • A portion of the dam will be preserved on the Howard County side for historical interpretation.

Materials presented at the Open House can be downloaded by clicking the link below:
Bloede Dam Removal Open House on January 29 (13MB sized file)
Bloede Dam Public Comments Response 2015

DNR and it's partners have completed the following tasks for developing the design plans:

  • DNR held an open house on January 29th to present the 60% design plans and inform the public of important topics which could impact them.
  • Posted responses to comments received at the open house.
  • Estimated sediment volumes using MD Geological Service seismic survey data and soil borings.
  • Analyzed sediment cores for physical properties and pollutants.
  • Met with permitting agencies to discuss the Bloede Dam removal options.
  • Met with Baltimore and Howard County Department of Public Works to discuss options for minimizing impacts to the sewer line.

Looking ahead, DNR and it's partners will work on the following tasks:

  • Continue to coordinate with Baltimore and Howard County on the sewer line relocations.
  • Continue coordination with the Maryland Historical Trust to mitigate historical losses.
  • Provide updates on this page and through social media regarding construction start dates, trail closures, and potential impacts to park users.

Tentative timeline:

  • Permits are expected from resource agencies in the fall of 2015, with sewer line relocation beginning in winter 2015 and lasting approximately 1 year.
  • Dam removal will begin in winter 2016, with tree plantings occurring in spring 2017.


Bloede Dam Project

Problem: The Bloede Dam is located within the Patapsco River State Park and was built in 1907. The dam is a public safety concern (deaths have occurred), an obstacle for fish passage, and it fragments river continuity and aquatic habitats.

Responsibility: Bloede dam is owned by the Maryland Department of Natural Resources (DNR).

Process: A feasibility study was commissioned to evaluate the dam's negative impact on the ecology of the Patapsco River and issues of public safety. After a thorough analysis and public input (2011-2012), the Department and project partners made the decision to move forward with the Bloede Dam removal with passive sediment management.


Goals of the Bloede project:

  1. Restore Fish and Aquatic Organism Passage
    The Patapsco River once supported large runs of shad, herring, and American eels, but the construction of dams has blocked these historic migrations. The fish ladders constructed in the 1990's have proven to be ineffective at passing fish – especially American eel.p>
  2. Improvement of Public Safety
    The Bloede dam is a significant public safety hazard, several deaths have occurred at or near the dam.
  3. Consider Historic, Cultural and Recreational Values
    The Bloede Dam was built in the early 1900’s and is part of the Patapsco’s rich history. It is also a major feature of the Patapsco Valley State Park. Similarly, herring, and shad were once abundant and a staple of settlers in the Patapsco Valley. The cultural significance of each of these will be commemorated as part of this project and recreational boating and fishing values promoted.


Our Vision

With the removal of all or most of Bloede Dam, DNR envisions a restored Patapsco River System with a wide range of benefits and long-term cost savings. It is recognized that this decision is not without potential adverse impacts.

A significant historical structure in Patapsco Valley State Park will be lost, there will be short-term impacts to the ecology of the river, fishing and other recreational opportunities will be affected, and there will be temporary inconvenience to park visitors.p>

However, there will be long-term ecological benefits to the Patapsco River and the Chesapeake Bay, including:

  • Passage of anadromous fish and eels, thus achieving fish passage objectives
  • Improved recreational opportunities (fishing, canoeing, kayaking, tubing) and enhanced public safety (removal of drowning hazard and elimination of dam-related injuries)
  • Healthier populations of native fish species
  • Increased diversity of aquatic insects
  • Cooler, oxygen-rich waters that improve the fishery
  • Long-term cost savings related to ongoing maintenance and repair of the dam structure and an ineffective fish ladder
  • A more scenic and natural setting; the present dam aesthetics that some find attractive will be replaced over time with a rocky, more natural cascading river environment and setting

To address the loss of a cultural and historic resource, a portion of the dam structure will be retained on the Howard County side with the placement of appropriate interpretive displays on location and possibly another interpretative display on the Baltimore County side.


The Department invites you to continue to submit written comments on this project, please email:


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